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1

Introducing the method of multielectrode arrays in the electrophysiological studies of the posterior hypothalamus in vitro

100%
Caban B., Kowalczyk T., Zoladz M., Rauza J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Theta rhythm is the best synchronized EEG activity recorded from the mammalian brain. The generation of theta in the limbic structures depends on activation of the ascending brainstem-hippocampal synchronizing pathway. One of the main structures of this pathway is the posterior hypothalamic area (PHa) which most probably modulates hippocampal theta frequency. Multielectrode Arrays (MEA) are a well-known tool in both in vivo and in vitro electrophysiology. Our new in vitro multi-recording setup is constructed using a glass multielectrode matrix consisting of 256 electrodes fitted on 10 square mm. Each electrode is 40 μm high, cone-shaped and represents a single field recording channel. During experiments, brain slices are constantly perfused with prewarmed and oxygenated cerebrospinal fluid which prevents the tissue from dying and allows direct administration of chemicals. Our previous in vitro experiments show that the PHa is capable of generating local theta rhythm in both in vitro and in vivo conditions. The aim of the current study was to introduce a new method of in vitro multisite recordings from posterior hypothalamic slices. Application of MEA recording method in the studies of PHa theta rhythm is discussed. Supported by NCN grant 2011/01/B/ N24/00373.
2

The effect of carbenoxolone on carbachol-induced posterior hypothalamic theta in vitro

88%
Kowalczyk T., Caban B., Bocian R., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Current evidence strongly suggests that gap junctions (GJs) communication underlies the mechanisms of oscillation and synchrony in the central nervous system. In our previous work we have documented that GJs are highly involved in the generation of theta rhythm in both in vivo and in vitro hippocampal formation. Specifically, the blockage of gap junction by application of carbenoxolone (CBX) abolished hippocampal theta field potential and this effect was found to be hardly reversible. In our recent studies we have showed that posterior hypothalamic area (PHa), well known as an extrinsic modulator of hippocampal theta frequency, is also capable of independent theta rhythm generation. The aim of the present study was to investigate the effect of gap junctions blockage on cholinergically-induced posterior hypothalamic theta in vitro. Two experimental procedures were applied. (1) PHa slices were preincubated in 100 μM CBX and then theta rhythm was eleicited by 50 μM carbachol (CCH); (2) PHa theta activity was induced by perfusion of the slices with 50 μM CCH, and then the slices were perfused with 50 μM CCH + 100 μM CBX. In both experimental conditions the blockage of gap junctions with carbenoxolone failed to abolish the cholinergic theta rhythm in the posterior hypothalamic area. The mechanisms underlying the generation of PHa theta activity are discussed. Supported by NCN grant 2011/01/B/N24/00373.
3

Local theta rhythm mapping studies of posterior hypothalamus in vitro

76%
Caban B., Klos-Wojtczak P., Kowalczyk T., Bocian R., Kuzmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2014
|
tom 74
|
nr 3
Theta rhythm is one of the finest examples of synchrony in the mammalian brain. Hippocampal formation (HPC) theta is best described in rats and this EEG pattern consists of very regular, almost sinusoidal waves in the frequency range of 3–12 Hz. It is well-known that HPC theta rhythm is a result of the ascending brainstem-hippocampal synchronizing pathway activation, which originates in the pons and then projects to posterior hypothalamus, medial septum, and finally to the HPC. Recently, we have shown that administration of cholinergic agent – carbachol (75 μM), induces theta rhythm in in vitro maintained posterior hypothalamic area (PHa), specifically supramammillary nucleus (SuM) and posterior hypothalamic nuclei (PH). The purpose of this mapping study was to present the topography of areas capable of generation local theta rhythm in PHa slices as a result of carbachol administration. Supported by NCN grant 2011/01/B/N24/00373.
4

Theta oscillations in a novel in vitro preparation of posterior hypothalamus

76%
Kowalczyk T., Golebiewski H., Caban B., Bocian R., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2011
|
tom 71
|
nr S
Theta rhythm is the best synchronized EEG activity recorded from the mammalian brain. In rodents, this EEG pattern consists of high-voltage, regular, almost sinusoidal oscillations in the frequency range of 3-12 Hz. Hippocampal formation (HPC) is considered to be the main structure involved in the generation of this activity. Extensive anatomical and electrophysiological studies performed in rodents have revealed that the ascending brainstemhippocampal synchronizing pathway originates in the nucleus reticularis pontis oralis (RPO), next RPO fibres ascend to posterior hypothalamic (PH) region and then PH neurons projects to medial septal area which is well known as a hippocampal theta rhythm “pacemaker”. Earlier results suggest that the posterior hypothalamic region is only a modulator of hippocampal formation type II theta. Our preliminary studies suggest that this area is also capable of generation of local type II theta, which can be produced independently of the HPC theta rhythm. The purpose of the present study was to evoke the theta activity by tonic cholinergic (carbachol) or cholinergic/GABAergic (carbachol/bicuculine) bath perfusion in completely deaferentated posterior hypothalamus i.e. in novel PH slice preparations maintained in vitro. Experiments were performed on 25 posterior hypothalamic slices delivered from 25 Wistar rats. Slices were perfused with artificial cerebrospinal fluid containing carbachol (50 μM; 10 slices) or carbachol and bicuculine (50 μM and 10 μM respectively; 15 slices). Well synchronized hypothalamic theta activity was recorded in 7 carbachol-treated PH slices and in 13 PH slices perfused with carbachol/bicuculine.
5

Is orexin A involved in generation of the hippocampal theta rhythm? In vivo approaches

76%
Klos-Wojtczak P., Caban B., Bocian R., Kowalczyk T., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2014
|
tom 74
|
nr 3
Orexins are mainly synthesized in lateral hypothalamus but orexinergic projections are present in many brain areas including cerebral cortex, thalamus, brain stem and the hippocampal formation (HPC). The study was designed to check wheather intrahippocampal injections of orexin A and blockers of orexin receptors exert effect on theta. The studies were performed on anasthetized rats. Initially spontaneous theta rhythm recorded from HPC was blocked by the intravenous injections of atropine. When the HPC theta disappered, animals were subjected local injections of orexin A and the mixture of: orexin A and SB, orexin A and TCS and orexin A with both blockers in separate studies. Theta activty was only observed in the first and second case but with a lower parameters in comparison to theta recorded after orexin A injection. Obtained results indicates crucial role of orexinergic receptors underlying theta HPC rhythm production.
6

Are GAP junctions or mineralocorticoid receptors involved in generation of posterior hypothalamic theta in rat ?

76%
Bocian R., Kowalczyk T., Caban B., Kazmierska P., Klos-Wojtczak P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
There is a large body of research indicating that occurrence of hippocampal (HPC) theta dependent on the integrity of ascending pathway originating in the brainstem reticular formation. Anatomical studies indicate that reticular influences are relayed via the posterior hypothalamus, specifically the posterior hypothalamic (PH) and supramammillary (SuM) nuclei. In addition, neurons localized in these nuclei discharge rhythmically and in phase with HPC theta. Recently we have shown that local theta activity could be generated in anesthetized rats in PH and SuM nuclei. Recorded signal was produced independently of simultaneously occurring HPC theta and had a cholinergic profile. In the preset study we extended pharmacological observation; specifically, carbenoxolone (CBX – 75 μg/ μl; gap junction (GJ) blocker and mineralocorticoid receptor agonists) was administrated into posterior hypothalamus in urethanized rats. Injection of CBX, induced well synchronized theta activity. The effect of CBX was not antagonized by injection of GJ opener – trimethylamine (45 μg/μl) – but was abolished by antagonist of mineralocorticoid receptor, spironolactone (10 μg/1 μl). These results demonstrate for the first time that PH theta is mediated not by GJ but by mineralocorticoid receptors. Studies supported by NCN grant no. 2011/01/B/NZ4/00373.
7

Posterior hypothalamic theta rhythm and local cell discharges in adult anesthetized rats

76%
Bocian R., Klos-Wojtczak P., Caban B., Kowalczyk T., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Theta rhythm is the best synchronized electroencephalographic activity that can be recorded in several brain regions, for example, in the cingulate cortex, entorhinal cortex, and hippocampal formation (HPC) that is considered to be the main structure involved in the generation of theta. Just recently Kowalczyk et al. (2014) have indicated that this pattern EEG could also be observed in the posterior hypothalamic area (HPa) in anesthetized rats. Specifically, in the supramammillary (SuM) and posterior hypothalamic (PH) nuclei theta field activity was produced independently of simultaneously occurring hippocampal theta. Previous experiments have demonstrated that the HPC theta field activity is accompanied by a characteristic pattern of local cell discharges. PHa cells discharges were classified in accordance to earlier developed classification as theta-related and theta-nonrelated. Theta-related cells were classified as theta-on and theta-off. Both theta-on and theta-off cells were subclassified as phasic and tonic. The aim of the present studies was to describe firing cell repertoire during cholinergically induced theta rhythm in the PHa of rats. METHODS: All the experiments were performed in urethanized adult male Wistar rats. PHa theta rhythm and single cell activity were recorded with use of tungsten and glass microelectrodes respectively. RESULTS: One hundred fifty five out of 236 recorded in PHa cells were identified as theta non-related cells and 82 as theta-related cells: 48 theta-on, 29 theta-off, and 4 theta gating cells (the cells which activity is correlated with appearance of theta episodes). CONCLUSION: The obtained data clearly demonstrates that cholinergically induced theta activity in PHa, similarly to the HPC theta, is accompanied by local cell discharges which can be successfully classified in accordance with earlier developed criteria for HPC theta. The study was supported by National Science Centre (NCN, 2013/11/B/NZ4/04872).
8

Timing cells and carbachol induced theta rhythm in posteriol hypothalamic slice preparations of adult rats

76%
Bocian R., Caban B., Kowalczyk T., Klos-Wojtczak P., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Just recently we discovered a local theta rhythm in the posterior hypothalamic area (PHa) in in vitro and in vivo conditions. Theta rhythm which appeared in the PHa was produced independently of simultaneously occurring hippocampal formation theta. In the present study we analyse the correlation of local PHa cells discharges with carbachol induced theta field potentials. Specifically, we emphasise a novel type of theta related cells which we labelled “timing cells”. METHODS: Ninety experiments were conducted on the Wistar rat’s PHa slice preparation. The local theta field potential was induced with 75 μM carbachol. Glassrecording electrodes were positioned with use of micropositioner in different regions of PHa (mainly supramammillary nuclei). Single cell activity and local field potentials were recorded simultaneously with the same electrode with respect to the ground. RESULTS: Sixty nonrelated and more that 50 theta-related cells were recorded.  Twelve of theta-related cells were recognized and labelled as “timing cells”. These cells discharge rhythmically in the frequency range of 5–8 Hz and can be phase locked with local field potentials which appeared in 1–3 s lasting theta epochs. CONCLUSION: Posterior hypothalamic theta “timing cells” are probably involved in mechanisms responsible for programing the frequency of local theta field potentials and hippocampal formation theta rhythm.
9

Cellular correlates of kainate-induced posterior hypothalamic theta rhythm in vitro

76%
Caban B., Staszelis A., Kazmierska P., Siwiec M., Sowa J., Kowalczyk T.
Acta Neurobiologiae Experimentalis
|
2018
|
tom 78
|
nr Suppl.1
Hippocampal formation (HPC) theta rhythm is known to be one of the most synchronized EEG pat‑ terns in mammals. Theta field potentials in the HPC of rats are high‑amplitude, almost sinusoidal, waves in a 3‑12 Hz frequency range. It is well‑known that the posterior hypothalamic area (PHa including the supra‑ mammillary nucleus and posterior hypothalamic nuclei) is an important node in the pathway of HPC theta gen‑ eration, i.e. the ascending brainstem‑hippocampal syn‑ chronizing pathway. Furthermore, HPC theta frequency is at least partially modulated by the PHa through the activity of neurons firing in the frequency of HPC the‑ ta, at least during animals’ immobility‑related behav‑ iors. The PHa is thought to complement the activity of the medial septal area, widely known as the pacemaker of HPC theta rhythm. However, in our previous studies we discovered for the first time that cholinergic theta rhythm can also be recorded locally in deafferented pos‑ terior hypothalamic slices. Hence, in the present study we investigated PHa‑recorded theta‑related single cell activity in relation to local theta rhythm following ka‑ inic acid administration. 36 in vitro experiments were performed using brain slices (=72) taken from 36 adult Wistar rats. Each slice was perfused with 0.1 μM kain‑ ic acid to induce rhythmic activity and neuronal firing. Both field activity and corresponding cellular activity were recorded extracellularly. The relation of neuronal firing patterns to local field theta rhythm was investi‑ gated according to an existing universal classification of HPC theta‑related neurons. This study resulted in re‑ cording 17 theta‑related neurons and 77 neurons classi‑ fied as non‑related to local theta rhythm. A new neuron type (=21 cells) has been identified amongst the non‑re‑ lated group, which we termed timing cell, with a very rhythmic firing pattern in a nearly fixed frequency in the theta band. Kainate‑induced neuronal activity, re‑ corded in the posterior hypothalamic area in vitro, re‑ sembles cholinergically‑induced PHa neuronal activity, as well as well‑documented patterns of theta‑related cell discharges in the hippocampal formation in vitro and in vivo. Newly discovered PHa timing cells are discussed in light of an HPC theta rhythm frequency control mecha‑ nism. Supported by National Science Centre, Poland, No. UMO‑2017/25/B/NZ4/01476.
10

NMDA-induced posterior hypothalamic theta rhythm recorded in vitro

76%
Staszelis A., Caban B., Kazmierska-Grebowska P., Sowa J. E., Siwiec M., Kowalczyk T.
Acta Neurobiologiae Experimentalis
|
2019
|
tom 79
|
nr Suppl.1
INTRODUCTION: Theta rhythm is one of the brain rhythms’ patterns, which are evidence for neuronal synchrony. This pattern of rhythmic activity is related to sensorimotor integration, mnemonic functions, or spatial orientation and navigation. However, it is also linked to pathological conditions, for instance: Alzheimer’s disease, post‑traumatic stress disorder, and depression. In the last decade, we discovered that the posterior hypothalamic area (PHa) is not only a modulator of brainstem information going to the hippocampus, but also is capable of generating theta rhythm independently. AIM(S): The aim of the present study was to determine if NMDA (N-Methyl-D-aspartic acid) is capable of eliciting well-synchronized theta activity in PHa preparations. METHOD(S): The study was performed on 40 PHa slices prepared from 20 male Wistar rats. Each animal was anesthetized with isoflurane and decapitated. The PHa slices were dissected and transferred into the recording chamber, perfused with artificial cerebrospinal fluid, and treated with NMDA (300 µM) and D-AP5 (D‑(–)‑2‑amino‑5‑phosphonopentanoic acid) (200 µM). The field recordings were performed with glass electrodes filled with 2.0 M sodium acetate. RESULTS: Perfusions of PHa slices with 300 µM NMDA resulted in well-synchronized theta episodes which were blocked after the path application of 200 µM D‑AP5. CONCLUSIONS: The present data shows that excitation of NMDA-type glutamatergic receptors in PHa neural networks leads to the generation of local theta rhythms. FINANCIAL SUPPORT: Supported by NCN grant no. 2017/25/B/NZ4/01476.
11

Glutamatergically-induced theta oscillations recorded in both in vitro and in vivo maintained posterior hypothalamic preparations

76%
Kowalczyk T., Bocian R., Caban B., Golebiewski H., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2012
|
tom 72
|
nr 2
Theta rhythm is the best synchronized EEG activity recorded from the mammalian brain. In rodents this EEG pattern consists of high-voltage, almost sinusoidal oscillations in the range of 3–12 Hz. Hippocampal formation (HPC) is considered to be the main structure involved in the generation of this activity. Anatomical and electrophysiological studies have revealed that the ascending brainstem hippocampal synchronizing pathway, which originates in pontine region, constitutes a major source of extensive inputs to the HPC. Fibres from pontine nuclei ascend to the posterior hypothalamic (PH) area and then PH neurons projects to medial septal area. There are evidences from physiological and pharmacological studies supporting the view that the PH region forms a critical part of the ascending synchronizing pathway linking the rostral pontine region with the septo-hippocampal pathways. In our previous studies we have demonstrated that posterior hypothalamic region was able to generate the cholinergically-induced type 2 theta rhythm in both in vitro and in vivo conditions. The purpose of the present study was to evoke theta-band oscillations in PH area using the glutamatergic agonist – kainic acid. We have shown that application of kainic acid resulted in the generation of well-synchronized theta activity in PH slices maintained in vitro as well as enhancement of spontaneous theta recorded from posterior hypothalamic region of anaesthetized rat. Mechanisms underlying the generation of glutamatergically-induced theta oscillations in both in vitro and in vivo posterior hypothalamus are discussed. Supported by NCN grant no. 2011/01/B/NZ4/00373.
12

Theta oscillations in the posterior hypothalamic area-in vivo approach

76%
Bocian R., Klos-Wojtczak P., Kowalczyk T., Caban B., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2014
|
tom 74
|
nr 3
Numerous studies showed that occurrence of hippocampal theta rhythm is critically dependent on the integrity of a number structures localized at the level of brainstem and diencephalon. In detailed electrophysiological studies, conducted on anesthetized rats, we demonstrated that the posterior hypothalamic area (PHa), is not only a modulator of hippocampal formation theta but also could generate theta activity independently. The most effective areas in generation of examined EEG pattern were the supramammillary and posterior hypothalamic nuclei. Pharmacological manipulation reviled that PHa theta activity had a cholinergic (muscarinic) profile. Local injection of orexin A and B never induced theta activity in PHa. Finally, we showed that mineralocorticoid receptor but not gap junction play crucial role in generation of the posterior hypothalamic theta rhythm. Studies supported by NCN grant no. 2011/01/B/NZ4/00373.
13

5-HT1A receptors are involved in the development of theta oscillations in hippocampal formation in vitro

76%
Kazmierska P., Urbaniak L., Caban B., Bocian R., Kowalczyk T., Wieczorek M., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Hippocampal formation (HPC) is a limbic structure that generates a synchronized EEG activity, termed the theta rhythm. The theta rhythm is a sinusoidal activity with a frequency band ranging from 3 to 12 Hz. Many years of research conducted with the use of the model of HPC slice preparations allowed to determine the specific role of the cholinergic and GABAergic systems in the production of this EEG pattern. In addition, the literature data indicate that serotonergic input may be involved in the desynchronization of hippocampal theta. To verify this suggestion a micro-EEG recording were performed on HPC slices obtained from 20 male Wistar rats. All experiments were monitored by a Local Ethical Commission. Field potentials and extracellular recordings were made from the CA3c hippocampal field during the bath perfusion of a 5-HT1A receptor antagonist, (S)WAY-100135 in a range of concentrations in the following µM ratio: 1:3: 10:30 and 100. Preliminary results showed that besides epileptiform discharges, oscillatory activity in theta band was observed only in the slices perfused with 10 µM (S) WAY-100135. This demonstrates that the synchronization of neuronal networks needs the appropriate and precise level of excitation which can also be achieved by the manipulation of HPC 5-HT1A receptors activity. This study was supported by the NSC grant No.2011/01/N/ NZ4/01722.
14

Lamotrigine affects theta oscillations in the hippocampus of rats

76%
Caban B., Sowa J. E., Siwiec M., Bocian R., Kowalczyk T., Kazmierska-Grebowska P.
Acta Neurobiologiae Experimentalis
|
2019
|
tom 79
|
nr Suppl.1
INTRODUCTION: Neuronal synchronization depends on many factors including HCN channel action. They are voltage-gated ion channels that mediate an inward cationic current dependent on hyperpolarization. There is sparse evidence for their contribution to neuronal plasticity, learning and memory, epilepsy, or Alzheimer’s disease. HCN channels can be found in the hippocampus (HPC) and are thought to be involved in neuronal synchronization through initiating membrane potential oscillations which are necessary for the appearance of field theta oscillations. Hippocampal theta rhythm is known to be involved in memory formation, spatial navigation, sensorimotor integration, movement initiation, and others. So far it is established that HPC theta generation is a result of a fine balance between the cholinergic and GABAergic system activation, which triggers the synchronous action of theta-related neurons. However, the involvement of HCN channels in this process is still mostly unknown. AIM(S): The aim of this study was to investigate the role of HCN channel activation in the process of theta generation. METHOD(S): Three experimental models were used: in vivo anesthetized rats, in vitro acute HPC slices, and HPC patch clamp whole cell method. Field and single neuron recordings were made from the HPC after perfusion with a non-specific HCN channels agonist – lamotrigine (LTG). RESULTS: When LTG was applied it produced mixed results. In particular, it blocked theta rhythm in vitro but significantly enhanced it in vivo. Patch clamp results have shown that LTG reduced the frequency of spontaneous inhibitory postsynaptic currents but also decreased the excitability and membrane resistance of CA1 neurons. Also, LTG reduced membrane potential theta resonance in most CA1 cells. CONCLUSIONS: HCN channels activation was shown to have an impact on the process of theta rhythm generation in the HPC. Current results are discussed. FINANCIAL SUPPORT: Supported by National Science Centre, grant no. 2017/26/D/NZ4/00159.
15

Posterior hypothalamic "timing cell" activity and kainite-induced local theta rhythm in both in vitro and in vivo preparations

76%
Kowalczyk T., Staszelis A., Kazmierska-Grebowska P., Sowa J. E., Siwiec M., Caban B.
Acta Neurobiologiae Experimentalis
|
2019
|
tom 79
|
nr Suppl.1
INTRODUCTION: Theta rhythm typically occurs during memory processes, REM sleep, and spatial navigation but also in epilepsy, migraines, or even mild Alzheimer’s disease (AD). Recent evidence shows that well-synchronized theta rhythm can successfully be recorded locally from the posterior hypothalamic area (PHa), specifically from the supramammillary nucleus (SuM) and the posterior hypothalamic nuclei (PH). The population of theta-related cells in the PHa were found to be similar types to those found in the hippocampal formation. In addition, a new type of cells has been found in the posterior hypothalamic region and based on its regular firing pattern and possible pacemaker role these cells were termed “timing”. AIM(S): The aim of the present study was to investigate the timing of cell populations in both in vivo and in vitro PHa after theta rhythm induction by kainic acid (KA) application. METHOD(S): Twenty in vivo experiments were performed on 20 urethanized rats and 22 in vitro experiments were performed on 40 PHa slices obtained from 22 rats. Theta rhythm and single unit activity were evoked by intra-PHa microinjection of KA (in vivo) or by bath perfusion of PHa slices with KA-containing artificial cerebrospinal fluid (in vitro). RESULTS: A total number of 123 posterior hypothalamic neurons were recorded during both in vivo and in vitro experiments. Among them, 28 neurons were classified as “timing cells” according to their very regular pattern of discharges in a steady frequency in the theta band (3‑12 Hz). Eight timing cells were recorded in in vivo PHa and 20 timing cells were recorded in PHa slices. CONCLUSIONS: The present data show that glutamatergic stimulation of PHa neuronal network with kainic acid results in the activation of specific subpopulation of neutrons, characterized by regular firing pattern in theta frequency range. The role of PHa “timing cell” activity is discussed regarding hippocampal theta rhythm frequency programing. FINANCIAL SUPPORT: Supported by NCN grant No. 2017/25/B/NZ4/01476.
16

Theta rhythm and local cell discharges recorded in posterior hypothalamic slices of the adult rat

76%
Caban B., Klos-Wojtczak P., Kowalczyk T., Bocian R., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Hippocampal formation (HPC) theta rhythm is one of the best examples of neural synchrony in mammalian brain. HPC theta field potentials in rats consists of high-amplitude, almost sinusoidal waves in 3–13 Hz frequency range. It is wellknown that the pathway of theta generation originates in the nucleus reticularis pontis oralis (RPO), then RPO projects to supramammillary nuclei (SuM), and finally through the medial septal area (MS) to HPC and other limbic structures. This tract is called the ascending brainstem-hippocampal synchronizing pathway. In vivo, HPC theta frequency is modulated at least partially by SuM which consists of neurons firing in the frequency of HPC theta. However, in our previous studies we have discovered for the first time that local theta activity can also be recorded in deafferented posterior hypothalamic preparations. The present in vitro study investigates theta-related neurons and their relation to local hypothalamic theta rhythm. METHODS: 56 in vitro electrophysiology experiments were performed using brain slices taken from 56 Wistar rats. Each slice was perfused with 75 µM carbachol (cholinergic agonist) to induce rhythmic activity. The relation of firing neurons to local field theta rhythm was investigated according to an earlier developed classification. RESULTS: This study resulted in recording 21 theta-related neurons and 35 neurons classified as non-related to theta. CONCLUSION: Neuronal activity recorded in the posterior hypothalamic area in vitro resembles well-documented patterns of thetarelated cell discharges in the hippocampal formation in vitro and in vivo. Supported by NCN grant 2013/11/B/NZ4/04873.
17

Theta oscillations in the posterior hypothalamic area-in vitro approach

76%
Kowalczyk T., Caban B., Bocian R., Klos-Wojtczak P., Kazmierska P., Konopacki J.
Acta Neurobiologiae Experimentalis
|
2014
|
tom 74
|
nr 3
Hippocampal formation (HPC) theta rhythm is the largest rhythmical waveform generated by the mammalian brain. Studies performed in rodents revealed that the ascending brainstem-hippocampal synchronizing pathway originates in the nucleus reticularis pontis oralis (RPO), next RPO fibres ascend to posterior hypothalamic area (PHa) and then PHa neurons project to medial septum, known as a hippocampal theta “pacemaker”. Posterior hypothalamic area forms a critical part of that pathway, serving as a modulator of theta rhythm recorded in the HPC. However, two years ago we have discovered that the PHa is also capable of independent generation of local theta. The first aim of the present work was to review the data concerning local theta rhythm in the posterior hypothalamic area in vitro. The second aim was to perform the comparison between basic features of theta activity observed in the PHa and hippocampal formation in in vitro conditions. Supported by NCN grant 2011/01/B/N24/00373.
18

Postnatal development of theta-related cell activity in posterior hypothalamic slices

76%
Konopacki J., Caban B., Kazmierska P., Bocian R., Klos-Wojtczak P., Staszelis A., Kowalczyk T.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: Hippocampal formation (HPC) theta rhythm is one of the best examples of neural synchrony in the mammalian brain. It is well-known that the pathway of theta generation originates in the pons, from where it projects to the posterior hypothalamic nuclei, and finally through the medial septal area reaches the HPC. Recent evidence shows that well-synchronized theta rhythm can also successfully be recorded locally from the posterior hypothalamic area (PHa) maintained in vivo and in vitro, specifically from the supramammillary nucleus (SuM) and the primary posterior hypothalamic nuclei (PH). Furthermore, the neuronal activity of the PH and SuM nuclei can be characterized according to the universal classification of theta-related cells which was earlier created for the hippocampus. AIM(S): The purpose of the present study is to investigate theta-related cell activity in posterior hypothalamic slices taken from adolescent rats in order to examine the age at which theta rhythm and accompanying theta-related neuronal activity appears in rats’ PHa. METHOD(S): Forty‑five experiments have been carried out using brain slices taken from 55 Wistar rats aged: 8–10 (A); 13–15 (B); 18–19 (C) and 22–24 (D) days. Each brain slice was perfused with 75 µM carbachol (cholinergic agonist) to induce theta rhythm and accompanying theta-related cell activity in the SuM and PH nuclei. RESULTS: This study resulted in recording 16 theta-related neurons, 56 timing neurons, and 103 neurons classified as non‑related to PHa theta among three experimental groups (B–D). There was no significant theta oscillations and accompanying cell discharges in slices taken from 8–10 days old rats. CONCLUSIONS: Theta oscillations as well as theta-related neuronal activity can be observed in PHa slices delivered from rats not younger than 13–15 days. FINANCIAL SUPPORT: Supported by NCN grant 2013/11/B/NZ4/04872.
19

Spatiotemporal characterization of mTOR kinase activity following kainic acid induced status epilepticus and analysis of rat brain response to chronic rapamycin treatment

64%
Macias M., Blazejczyk M., Kazmierska P., Caban B., Skalecka A., Tarkowski B., Konopacki J., Jaworski J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Mammalian target of rapamycin (mTOR) is a protein kinase that senses nutrient availability, trophic factors support, cellular energy level, cellular stress, neurotransmitters and adjusts cellular metabolism accordingly. Recently, several groups reported that seizures increase mTOR activity, and such increased activity in genetic models can contribute to spontaneous seizures. However, the current knowledge about the spatiotemporal pattern of mTOR activation induced by proconvulsive agents is rather rudimentary. Also consequences of insufficient mTOR activity on a status epilepticus are poorly understood. Here, we investigated these two issues. We showed that mTOR signaling was activated by kainic acid (KA)-induced status epilepticus through several brain areas as well as revealed two waves of mTOR activation: an early wave (2 h) that occurs in neurons and a late wave that predominantly occurs in astrocytes. Unexpectedly, we found that pretreatment with rapamycin, a potent mTOR inhibitor, gradually (1) sensitized animals to KA treatment and (2) induced gross anatomical changes in the brain. Supported by Polish National Science Center OPUS grant (2012/05/B/ NZ3/00429)
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