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1

Physiological adaptations of motor units to endurance and strength training

100%
Mrowczynski W., Lochynski D.
Trends in Sport Sciences
|
2014
|
tom 21
|
nr 3
The motor units consisting of motoneuron and muscle fibers, is the smallest functional unit of the neuromuscular system, which has ability to adopt plastically to acting stimuli. The increase of the physical activity, evoked by various type of trainings is one of the most important factors which induces morphological, biochemical and physiological changes in motor units. Endurance and strength training are two forms of physical activity leading to differential modifications in physiological features of motor units. Endurance training improves ability of muscle to sustain contractile activity for a long time, while strength training improves muscle strength and power. This manuscript summarizes the knowledge on the essential physiological adaptations in the both components of motor units – motoneuron and muscle fibers to endurance and strength training. The main aim of this paper is to enhance understanding on the strategy by which the neuromuscular system optimizes its activity in order to improve capabilities of the skeletal muscles to both forms of physiological activity.
2

Tetanic depression of fast motor units during gradually increasing frequency of stimulation

100%
Lochynski D., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 3
3

Effects of ageing on the regulation of force in the rat medial gastrocnemius motor units

81%
Lochynski D., Krutki P., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
4

Effects of progressive weight lifting training on motor unit contractile properties

81%
Lochynski D., Kaczmarek D., Mrowczynski W., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Strength training increases muscle strength and contractile speed. The purpose of the study was to examine basic motor unit (MU) contractile properties of medial gastrocnemius muscle after 5 week progressive strength training in adult rats. Three and half mo rats were randomly assigned to the two groups: untrained control and progressive weight lifting (PWL). Conditioned by food reward PWL rats performed “squat-rise to toes-squat” type exercises 5 days/week in the custom made apparatus, which intensity grew from 70 up to 85% of one-repetition maximum during applied training period. MUs were functionally isolated by ventral root filament splitting, and classified according to the fatigue index and “sag” property into slow (S), fast resistant to fatigue (FR) and fast fatigable (FF). For analysis, the peak force of the maximum tetanic contraction and the peak force and the contraction and relaxation times of the twitch were studied. The peak tetanus force increased in S and FR MUs. The twitch contraction time was shortened and the twitch-to-tetanus force ratio decreased in FF and FR MUs. These initial data indicate that a short-term PWL increases force of S and FR MUs and speed of contraction of fast MUs within fast-twitch skeletal muscle.
5

The tetanic depression in fast motor units of mammalian skeletal muscle can be evoked even by lengthening of one initial interpulse interval

81%
Sowinska Z., Celichowski J., Krutki P., Lochynski D.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
The tetanic depression is phenomenon observed when higher frequency of stimulation of fast motor units immediately follows the lower one. However, it is not known does only one prolonged fi rst interpulse interval can evoke this effect. This study was conducted on 27 fast motor units of cat and 47 units of rat medial gastrocnemius muscles. In experiments performed on the two species the following stimulation protocol was applied in the main part of experiment: (1) the 6-pulses train of stimuli at 20 Hz (cat) or 40 Hz (rat), i.e. at 50 and 25 ms interpulse intervals, (2) the 6-pulses train of stimuli with the fi rst interpulse interval prolonged from 50 ms to 100 ms (cat) or from 25 to 50 ms (rat) followed by 5 stimuli at 20 Hz (cat) or 40 Hz (rat), (3) the 6-pulses train of stimuli at 20 Hz (cat) or 40 Hz (rat). Effects of two-time prolongation of the fi rst interpulse interval were observed as a decrease of the force following the sixth stimulus in a train. The tetanic depression in rat motor unit tetani for fast fatigable (FF) units amounted to 5.39 ± 4.94% and 9.24 ± 4.13% for fast resistant (FR) units whereas in cats the mean values were 15.00 ± 10.15% and 27.00 ± 13.95% for FF and FR motor units, respectively. This results prove that the studied phenomenon infl uence the force development when the motoneuron begins the activity even with only one, fi rst prolonged interpulse interval.
6

Influence of 5-week whole body vibration training on motor unit contractile properties in the rat medial gastrocnemius muscle

81%
Lochynski D., Celichowski J., Kaczmarek D., Krutki P.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
The aim of the study was to determine the effect of the whole body vibration training on motor unit contractile properties in rat medial gastrocnemius.Two groups of Wistar rats trained 30 s (V30, n=4) or 4 × 30 s (V120, n=4) daily, 5 days weekly, for 5 weeks on vibratory platform (Power Plate®, USA, 2 mm vibration at 50 Hz) were compared to the control group (C, n=10). The employed vibration excited motor units through the stretch refl ex loop. Functional isolation of units was achieved by electrical stimulation of thin fi laments of the ventral roots. A total of 267 motor units were studied (56 in V30, 69 in V120, and 142 in C). They were classifi ed into: fast fatigable (FF), fast resistant to fatigue (FR) and slow (S) types.In the V30 and V120 group, no changes in the distribution of motor unit types were noted. For both groups the specifi c and the only change was a signifi cant increase in the twitch and maximal tetanus force in FF motor units. Additionally, for V120 group an increase in maximal tetanus force of S units was noted. For V120 group the contraction and relaxation times shortened in fast motor units and FF motor units became also less resistant to fatigue. It is shown that only a little increased daily physical activity induced by vibration considerably infl uences motor unit properties and FF motor units seem to be the most sensitive to vibratory stimulus.
7

Changes of motor unit contractile output during repeated activity

81%
Lochynski D., Celichowski J., Korman P., Raglewska P.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 1
The aim of the study was to evaluate changes in the motor unit output and to determine changes in the optimal stimulation frequency (i.e., giving the maximal output per one pulse) during prolonged contractile activity when, successively, potentiation of force and fatigue developed. The influence of these phenomena was studied on three types of motor units: fast fatigable (FF), fast resistant (FR) and slow (S) in the rat medial gastrocnemius muscle. The motor units were isolated by a method of splitting of L5 ventral root into very thin bundles of axons which were electrically stimulated 10 times with repeated series of 10 trains of stimuli at duration of 500 ms and progressively increasing (1-150 Hz) frequency. The initial (the first series of stimulating trains), potentiated (the second series), as well as fatigued (the tenths series) force recordings were compared. The motor unit output was expressed as the area under the force-time record in response to one stimulus measured at a plateau phase of the tetanic force. The stimulation frequency when the force-time area per one pulse was maximal was accepted as the optimal frequency. In fast motor units, the maximal contractile output increased with potentiation and was reduced with fatigue, and the optimal frequency decreased and increased, respectively. Nevertheless, the fusion degrees of the optimal tetanic contractions were similar in initial state, potentiation and fatigue independently of the changes in force. The applied stimulation protocol had almost no influence on the mechanical activity of slow motor units. The study highlights the physiological importance of force potentiation induced by preceding contractile activity for the economy of motor performance. The observed changes of the optimal stimulation frequency are consistent with the known changes in the motor unit firing rates during voluntary activity when the two phenomena develop.
8

Changes of motor unit contractile properties after long-term exposure to the whole-body vibration in the rat

81%
Krutki P., Kaczmarek D., Lochynski D., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2011
|
tom 71
|
nr S
Whole-body vibration (WBV) evokes increased activity of motor units (MUs) what is attributed to the enhanced afferent feedback and descending drive to the motoneuronal pool. In comparison to voluntary contractions, high-threshold MUs are more effectively activated during WBV due to lower recruitment thresholds of MUs during reflex contractions induced by mechanical vibration. Therefore WBV has been proposed to be a specific training for fast-twitch muscle fibers. Indeed, a 5-week WBV has been previously shown to induce the considerable increase of twitch and tetanic forces of FF MUs. The aim of the present study was to determine long-term effects of WBV on MU contractile properties. Two groups of Wistar rats were trained on the vibratory platform (Power Plate, USA) for 3 months or 6 months (4×30 s daily, at 50 Hz frequency, the peak-to-peak amplitude of 2.5 mm, the maximum acceleration of the platform 4.79 g). Results were compared to two control groups of normally active rats (matched with respect to age and body weight). Contractile properties were measured from functionally isolated MUs of the medial gastrocnemius muscle. Contrary to effects of short exposure to WBV, the long-term WBV did not changed significantly force parameters of FF units, only minor tendencies for an increase of tetanic forces of FF units were found after 3 or 6 months of WBV. It seems that effects of the WBV are temporary in FF MUs that adapt to longterm vibration stimuli. On the other hand, lower twitch forces, higher tetanic forces and a significant decrease of the twitch-totetanus force ratios were observed for FR and S MUs. Moreover, changes in proportion of fast MUs were observed after 3 and 6 months of WBV: the increase of a relative number of FF and the decrease of FR units. This suggests that the long-term WBV induces deeper processes that influence mechanisms of MU contraction (e.g., altered myosin heavy-chain expression or changed properties of motoneurones).
9

Agein affect the rate of force development of motor units in rat fast muscle

81%
Kaczmarek D., Lochynski D., Celichowski J., Krutki P.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
The rate of force development (RFD) of skeletal muscle decreases with ageing. The purpose of this study was to determine whether this phenomenon may be connected with the age-related changes in motor unit (MU) properties. One group of young (5–10 months old, n=9) and two groups of old (24–25 months old, n=6 and 28–30 months old, n=8) male Wistar rats were studied. Contractile activity of isolated MUs in the rat medial gastrocnemius muscle was evoked by electrical stimulation of ventral root fi laments. MUs were classifi ed into fast fatigable (FF), fast resistant (FR), and slow (S) according to susceptibility to fatigue and twitch contraction time. The RFD, force and force-time integral (FTI) of twitch, contraction following doublet pulse stimulation and maximal tetanus were measured and compared. Absolute and relative RFD of studied MUs evidently increased with ageing. We observed gradual augmentation of absolute force and FTI of evoked doublet contractions during ageing in S MUs while in FF units this increase was transient (only for 24–25 months old animals). However, the relative values of force and FTI after doublet stimulus were lower in S and FR MUs and unchanged in FF units in old animals as compared to the young. The increase in MU RFD is opposite to decrease in muscle RFD with ageing. The decline of the muscle performance capabilities can not be attributed to deterioration of mechanical parameters of survived MUs but rather is due to overall loss and change in proportion of MUs.
10

Motor unit action potentials in the medial gastrocnemius muscle of young and old rats

81%
Ciechanowicz I., Krutki P., Lochynski D., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
11

Properties of rhythmic firing of motoneurons are altered in response to weight-lifting training in rats

71%
Krutki P., Mrowczynski W., Baczyk M., Lochynski D., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: Repeated short-term and high--intensity exercises with a progressive external load are defined as strength or resistance training, which is responsible for an increase in muscle mass and force. AIM(S): The aim of this study was to determine whether strength training induces adaptive changes in firing properties of motoneurons (MNs) innervating the trained muscles. METHOD(S): The study was performed on adult male Wistar rats. Animals from the training group were subjected to a five‑week voluntary progressive weight‑lifting program, while control rats were restricted to standard cage activity. Intracellular recordings from lumbar spinal MNs innervating gastrocnemius and soleus muscles were made under pentobarbital anesthesia. RESULTS: The strength training evoked adaptive changes in both slow and fast-type MNs, indicating their increased excitability: a higher input resistance, a lower rheobase, a decrease in the minimum currents required to evoke rhythmic firing. The maximum frequencies of the early‑state firing (ESF) and of the steady‑state firing (SSF) were increased. Moreover, higher ESF and SSF slopes of the frequency-current relationship were observed in MNs of the trained group. Higher maximum firing rates of MNs as well as higher discharge frequencies evoked at the same level of intracellular depolarization current imply higher levels of tetanic forces developed by motor units over the operating range of force production after the strength training. CONCLUSIONS: This study provides evidence that the changes in spinal excitability following strength training observed in humans may be due to changes in the intrinsic properties of the MNs. The findings largely explain why some adaptations in the twitch and tetanus force development of motor units could be observed in response to the dynamic resistance training without qualitative changes in the muscle myosin heavy-chain expression. FINANCIAL SUPPORT: The study was supported by the National Science Center grant 2013/11/B/NZ7/01518.
12

Comparison of rat and cat motor unit properties in the medial gastrocnemius muscle

71%
Krutki P., Celichowski J., Lochynski D., Pogrzebna M., Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
13
Content available remote

Tetanic depression in fast motor units of the cat gastrocnemius muscle

71%
Celichowski J., Krutki P., Lochynski D., Grottel K., Mrowczynski W.
Journal of Physiology and Pharmacology
|
2004
|
tom 55
|
nr 2
Ability of muscle fibers to generate force is decreased when higher frequency of stimulation of motor units immediately follows lower frequency. This phenomenon called tetanic depression was found in rat medial gastrocnemius. However, it was not clear whether tetanic depression occurred only in rat muscle or it concerns all mammals. This study was conducted on motor units of cat medial gastrocnemius. Analyses were made at three successive trains of stimulation: 30 Hz, 20 and 30 Hz and again 30 Hz (the first pattern) or 40 Hz, 25 and 40 Hz and 40 Hz (the second pattern). In all fast units force generated within the middle tetanus was lower than force generated at the same, but constant frequency of stimulation applied earlier or later. The mean tetanic depression in 30 Hz tetani amounted to 10.9% for fast fatigable (FF) and 15.9% for fast resistant (FR) motor units, whereas in 40 Hz tetani mean values were 5.6% and 7.3% for FF and FR motor units, respectively. In slow motor units tetanic depression was not observed. These results proved the existence of tetanic depression in the feline muscle and indicated that its intensity depends on the fusion of tetanus. It has been concluded, that the tetanic depression is a general property of fast motor units in mammals.
14

The influence of beta-alanine suplementation on contractile properties of motor units in rat medial gastrocnemius

61%
Kaczmarek D., Lochynski D., Everaert L., Derave W., Rainczuk J., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Beta-alanine (BA) supplementation increases muscle carnosine concentration resulting in better muscle performance. In vitro experiments on isolated muscles and single muscle fibers indicated that carnosine improved excitation-contraction coupling and slowed fatigue. We investigated effects of BA supplementation on muscle carnosine levels and in vivo motor units (MUs) contractile properties in rat medial gastrocnemius muscle (MG). Ten male Wistar rats were randomly assigned to control (n=5) or BA (supplemented with 1% BA in the drinking water for 10 weeks; n=5) groups. Contractions of 258 MUs were evoked by electrical stimulation of ventral root filaments. MUs were classified into fast fatigable (FF), fast resistant (FR) and slow (S) according to the standard criteria. Twitch force (TwF), maximum tetanic force (TetF) and force profile during the fatigue test were analyzed. BA supplementation enhanced carnosine levels in white and red portion of MG muscle by 94% and 56%, respectively. After BA supplementation TwF in FF and TetF in FR MUs increased, and force was better maintained from 20th to 130th s of the applied fatigue test in FR MUs. In conclusion, BA supplementation primarily improves contractile performance of FR MUs.
15

Changes in contractile properties of motor units in rats with decreased muscle carnosine content after 14 days of histidine deprivation

61%
Kaczmarek D., Lochynski D., Pawlak M., Everaert I., Blancquaert L., Derave W., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Motor unit (MU) force is regulated by neural and muscular mechanisms. Recently, effects of carnosine on skeletal muscle contractility have been broadly studied. We found that increased muscle carnosine content by beta-alanine supplementation improved MU contractility. Several studies showed that histidine-free diet decreases carnosine content and causes weight loss, anaemia or hypoproteinaemia but its effect on muscle contractility is unknown. Here we studied MU contractile properties in histidine-deprived rats with reduced muscle carnosine content. METHODS: Ten 6 mo male Wistar rats were randomly assigned to experimental (HFD) or control (CON) group fed histidine-free or standard diet for 14 days, respectively. In order to maintain the same level of body mass loss food intake was controlled and balanced between both groups. Body mass decreased by 11.7 and 10.6% in HFD and CON groups, respectively. RESULTS: In HFD group carnosine levels were lower than in CON group in white and red portion of MG muscle by 26% and 34%, respectively. Histidine deprivation did not result in lower muscle mass or muscle-to-body mass ratio. In electrophysiological experiments contractions of MUs in medial gastrocnemius (MG) muscle were evoked by electrical stimulation of ventral root filaments. MUs were classified into fast fatigable (FF), fast resistant (FR) and slow (S). Maximum tetanic force (TetF) and force profile during the two separate fatigue tests were analysed. The TetF did not differ between groups either in fast or slow MUs. During the first fatigue test in FR MU force was initially higher but from 40 to 120 s it was lower in HFD animals. Unexpectedly, in the second fatigue test the force of FR and S MU was better maintained in HFD than CON rats. CONCLUSIONS: The results indicate that short-term histidine deprivation and the carnosine decrease do not attenuate force of MUs. Moreover, compensatory mechanisms may be involved in the regulation of MU force in this condition. Support: grant 2013/09/B/NZ7/02554.
16

Motor unit contractile properties and myosin heavy chain protein expression after resistance extercise

61%
Lochynski D., Kaczmarek D., Mrowczynski W., Majerczak J., Karasinski J., Zoladz J., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Expression of distinct types of myosin heavy chain (MHC) isoforms in skeletal muscle is accepted as one of critical factors providing the molecular basis of muscle fibre functional diversity and plasticity. However, chronic nerve stimulation experiments have provided a strong evidence that modifications in the contractile regulatory and the energy metabolism systems occur much earlier than transition of myosin isoforms. METHODS: In this study we investigated expression of MHC isoforms, contractile kinetics (twitch time characteristics), force regulation (force-frequency relationship), and fatigability of motor units in rat fast-type skeletal muscle at the early stage of voluntary progressive resistance exercise program. Motor units classified into slow (S), fast resistant to fatigue (FR) and fast fatigable (FF) were functionally isolated from medial gastrocnemius muscles of rats subjected to weight lifting (WL) exercises or control, sedentary animals. RESULTS: MHC isoform expression was not changed. Shortening of the twitch contraction was observed in both types of fast MUs. The twitch half-relaxation time of FF units was prolonged in WL animals. The contraction-to-half-relaxation time ratio (twitch shape) was significantly decreased in fast MUs of WL rats. Forcefrequency curve was shifted towards higher stimulation rates in FR but not FF units. In FF MUs of WL rats force declined less in time during initial 15 seconds and then was better maintained during the next 75 seconds of performed 180-second fatigue test. In FR units of WL rats force declined more in time during the last 120 seconds of the test. S MUs contractile parameters were not changed. CONCLUSIONS: At the early stage of resistance training modifications in the contractile regulatory and energy metabolism systems of fast MUs, as acknowledged by observed alterations in their contractile kinetics and fatigability, occur before any transition in muscle MHC isoforms is observed.
17

Changes in electrophysiological properties of rat motoneurons evoked by A5-week sterngth training

61%
Mrowczynski W., Lochynski D., Kaczmarek D., Baczyk M., Celichowski J., Krutki P.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Different forms of chronic physical activity evoke adaptive changes in the neuromuscular system. Long-lasting strength training, with repeated short-term and highintensity exercises, is responsible for an increase of muscle mass and generation of larger forces. However, adaptations in properties of motoneurons innervating muscles subjected to such training have been unknown so far. The aim of this study in the rat was to determine whether the strength training induces changes of passive and threshold membrane properties, and rhythmic firing of motoneurons. METHODS: The study was performed on eight adult Wistar rats, randomly assigned to the training or the control groups. Animals from the training group were nutritionally conditioned in order to make weightlifting put on their shoulders in a special apparatus with progressively increasing load, for 5 weeks. Acute electrophysiological experiments were performed on deeply anesthetized animals from both groups, using microelectrode intracellular recordings from motoneurons innervating hind limb muscles. RESULTS: It was demonstrated that 5-week strength training evoked adaptive changes in both fast and slow types of motoneurons: a shortening of the rise time of action potentials, an increase of the maximum frequencies of rhythmic firing, and an increase in the slope of the frequency-current relationship. CONCLUSIONS: Obtained data suggest higher susceptibility of motoneurons to an increased or decreased intensity of stimulation. Moreover, a decrease in rheobase currents, and a decrease in the minimum currents required to evoke rhythmic firing was observed in fast-type motoneurons only, suggesting their higher excitability. Supported by the National Science Center grant No. 2013/11/B/ NZ7/01518.
18

Adaptive changes in motor unit contractile properties to endurance training

61%
Krysciak K., Krysciak J., Lochynski D., Kaczmarek D., Drzymala-Celichowska H., Krutki P., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Endurance training is based on a repeated, prolonged activation of a large number of muscles. It causes morphological, biochemical and metabolic changes in the muscles and the nervous system. However, there are no data concerning changes in motor unit (MU) contractile properties following endurance training. METHODS: 61 male rats were assigned to 4 groups, untrained – control (C), and 3 groups trained on a treadmill, 5 days a week for 2 weeks (2W), 4 weeks (4W) or 8 weeks (8W). The special protocol determined duration and speed of locomotion in the consecutive days of the training. Finally, rats of the 2W group covered average distance of 5.5 km, 4W of 21 km, and 8W of 56 km. Afterwards, functionally isolated MUs of the medial gastrocnemius muscle were electrophysiologically investigated. RESULTS: The mean body mass of rats of all trained groups was lower in comparison to the C group, but no differences between 2W, 4W and 8W groups were noted. The muscle mass and the muscle-to-body mass ratio were not different between groups. The proportion of fast resistant (FR) MUs was higher, while of fast fatigable (FF) lower in all trained groups, in comparison to the C group. The relative number of slow (S) MUs increased only in the 8W group. MU contractile properties were changed mainly in FR MUs and included: lower contraction and half-relaxation times, lower twitch forces, higher tetanus forces and lower twitch-to-tetanus ratio. Few adaptive changes were noted also for S MUs of trained animals: lower twitch and tetanus forces as well as lower twitch-to-tetanus ratio. For FR and S MUs of all trained groups the force decrease within four minutes of the fatigue test was considerably slower or even completely abolished, which was reflected in the increased fatigue indexes. CONCLUSION: The main adaptive changes appeared early and then slowly increased within the endurance training. Supported by the National Science Center grant 2013/09/B/ NZ7/02555.
19

Effects of short- and long-term carnosine treatment on contractile properties of motor units in aged rats

51%
Pawlak M., Kaczmarek D., Lochynski D., Gartych M., Podgorski T., Borucka A. M., Everaert I., Derave W., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: Carnosine (beta-alanyl-L-histidine) is predominantly present in skeletal muscle but also in other excitable tissues. It was suggested that muscle carnosine concentration can decrease with ageing. There is growing evidence that supplementation of carnosine can be effective for the treatment of age related disorders as well as neurological disorders e.g. Alzheimer’s disease or Parkinson’s disease. AIM(S): Here we investigate the effects of orally supplemented carnosine in aged rats on motor units (MUs) contractile properties. METHOD(S): 42 male Wistar rats aged 15 months were randomly assigned to three groups: control (CON; n=15), treated with carnosine for 8 months (CAR8M; n=15) or treated with lated and fixed. In one set of experiments the brains were frozen and cut with the use of cryotome. Then, slices were used either for Nissl staining to visualise anatomical structure, or in situ hybridisation for gene expression analysis. In another set of experiments, fixed brains were dissected into two hemispheres, after which a small DiI crystal was inserted into the thalamus. After incubation, the hemispheres were cut with a vibratome and DiI-stained axons were visualised under fluorescent microscope. RESULTS: We show here, that TCF7L2‑deficent mice displayed major changes in the anatomy of the thalamus and habenulae, as well as partial malformations of the striatum. Furthermore, Tcf7l2-/- mice most often completely failed to produce thalamocortical axons; if some were visible, they did not reach their cortical targets. CONCLUSIONS: The study demonstrated a critical involvement of TCF7L2 in thalamic nucleogenesis and establishment of thalamocortical axons. FINANCIAL SUPPORT: Work supported by NCN grants 2011/03/B/NZ3/04480 and 2015/19/B/NZ3/02949.
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