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1

Opioid system in the pedunculopontine tegmental nucleus (PPN) suppresses cholinergic component of the hippocampal theta rhythm in urethane-anesthetized rats

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Leszkowicz E., Matulewicz P., Trojniar W.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
2

Temporal inactivation of the pedunculpontine nucleus suppresses hippocampal theta rhythm induced by electrical stimulation of the nucleus pontis oralis in rats

100%
Matulewicz P., Kusmierczak M., Orzel-Gryglewska J., Jurkowlaniec E.
Acta Neurobiologiae Experimentalis
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2011
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tom 71
|
nr S
Synchronous neuronal activity in the hippocampus (theta rhythm) can be elicited in urethanized rats with sensory stimulation as well as with electrical or pharmacological stimulation of different nuclei of the brainstem. It is known that two of these nuclei, the nucleus pontis oralis (RPO) and the pedunculopontine nucleus (PPN), play an important role in theta regulation, however, it is still unclear which of them is essential for expression of theta in the hippocampus. In the present study we investigated the effect of temporal inactivation of PPN on the hippocampal theta rhythm induced by electrical stimulation applied to RPO. The experiments were performed on 5 male Wistar rats in deep urethane anesthesia with its level monitored on the basis of breathing rate. Animals were implanted with bilateral recording electrodes into the dorsal hippocampus and stimulation electrode into the RPO. Hippocampal EEG was recorded during repeated electrical stimulation of RPO in control conditions and also following intra-PPN administration of procaine. In all animals electrical stimulation of the RPO (200 - 300 mA, 30 s) induced episodes of robust hippocampal theta rhythm in both hippocampi which lasted for the whole period of the electrical stimulation (30 s) with no latency. After temporal inactivation of the PPN by direct procaine microinjection (20% solution/0.5 μl), electrical stimulations of the RPO were not able to induce synchronous activity in the hippocampus. Neuronal activity within the RPO and PPN nuclei changes during sleep/wake cycle including paradoxical sleep, of which hippocampal theta rhythm is an important indicator. Regular theta rhythm in the hippocampus is also present during urethane anesthesia which was applied in our experiments. Our results indicate that undisturbed neuronal activity within the PPN is crucial for evoking hippocampal theta rhythm with electrical stimulation of RPO, which suggests superior role of the PPN.
3

Modulation of hippocampal theta rhythm by the opioid system of the pedunculopontine tegmental nucleus

100%
Leszkowicz E., Kusmierczak M., Matulewicz P., Trojniar W.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 4
The pedunculopontine tegmental nucleus (PPN) belongs to the brainstem system which synchronizes hippocampal activity. Theta relevant intra-PPN circuitry involves its cholinergic, GABA-ergic and glutamatergic neurons and Substance P as neuromodulator. Evidence that PPN opioid elements also modulate the hippocampal theta is provided here. In urethane-anesthetized rats a unilateral microinjection of morphine (MF) (1.5 and 5 µg) increased the maximal peak power of tail pinch-induced theta. The higher dose also increased the corresponding frequency. When the theta was evoked by intra-PPN injection of carbachol (10 µg), the addition of MF (5 µg) prolonged theta latency and shortened the duration of the theta. These effects of MF were blocked by naloxone (5 µg). The results obtained suggest that the PPN opioid system can enhance or suppress the hippocampal theta depending on the actual level of PPN activation.
4

State-dependent modification of high-frequnc oscillations in the rodent nucleus accumbens

100%
Hunt M., Matulewicz P., Gottesmann C., Kasicki S.
Acta Neurobiologiae Experimentalis
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2009
|
tom 69
|
nr 3
Spontaneous high frequency oscillations (HFO) in the local fi eld potential recorded in the nucleus accumbens (NAc) are typically represented by a small peak in the power spectra in the range of 140–180 Hz. These HFO are known to occur in the awake state, but their distribution over the sleep-wake cycle has not been investigated. To address this issue we fi rstly examined the power of HFO during periods of quiet waking, slow-wave sleep (SWS) and REM sleep. Since the electrophysiological activity during general anesthesia resembles certain features of naturally occurring SWS we went on to examine the effect of pentobarbital, isofl urane or urethane anesthesia on spontaneous and ketamine-induced increases in HFO. We found that the power of spontaneous HFO decreased signifi cantly during periods of SWS with respect to both quiet waking and REM sleep. General anesthetics also reduced the power of spontaneous HFO recorded in the NAc and completely blocked the ketamine-induced increase. These fi ndings suggest that behavioural states where the generation of mental activity is most intense are associated with the presence of HFO in the NAc. In line with this, states which lead to decreased mentation, such as naturally occurring SWS and general anesthesia are associated with reductions in the power of HFO. Together these fi ndings suggest that the presence of HFO may have behaviourally meaningful consequences.
5

The effect of gap junction blocker, carbenoxolone, on theta rhythm in anesthetized rats

100%
Matulewicz P., Konopacki J., Jurkowlaniec E.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
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