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Bilateral lesions of the pedunculopontine tegmental nucleus affect feeding induced by electrical stimulation of the ventral tegmental area.

100%
Trojniar W., Staszewska M.
Acta Neurobiologiae Experimentalis
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1995
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vol. 55
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issue 3
201-206
EN
The pedunculopontine tegmental nucleus (PPN) is anatomically connected with dopminergic cells in the ventral mesencephalon, which are known to participate in the regulation of various adaptive appetitive behaviours.In present experiment we studied a possible involvment of PPN in feeding elicited by the stimulation of the ventral tegmental area (VTA).It was found that bilateral electrolytic lesionong of the PPN affected VTA-elicited feeding.However, the effects were diverse and showed dependence on the localization of the lesion within the PPN area.Lesions localized anteriorly in the PPN impaired VTA feeding whereas those involving the middle portion of the nucleus facilitated electrically elicited food ingestion.A precise alignment of the lesion and the area activated at the site of stimulation appeared crucial for the effect of the lesion.The results indicate that PPN belongs to the central feeding circuitry and it contains both activating and inhibiting elements directed to the ventral tegmental area.
2
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Augmentation of ventral tegmental area stimulation-induced feeding by both stimulation and lesion of the contralateral ventral tegmental area in the rat

100%
Maliszewska- S. M., Trojniar W.
Acta Neurobiologiae Experimentalis
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1999
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vol. 59
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issue 4
287-293
EN
Unilateral lesions of the ventral tegmental area (VTA) facilitate behavioral responses (feeding and exploration) induced by electrical stimulation of the VTA in the contralateral hemisphere. It was hypothesized that this facilitation may result from a lesion-induced compensatory increase in dopamine transmission in the intact hemisphere. In the present study we tested on the functional level the hypothesis that the activity of bilateral mesocorticolimbic systems is inversely related. For this purpose we compared the effect of unilateral subthreshold activation with the effect of subsequent unilateral lesion of VTA on feeding response evoked by electrical stimulation of the contralateral VTA. In male Wistar rats implanted with bilateral VTA electrodes stimulation-induced feeding was tested in a latency to feed - -stimulation frequency curve-shift paradigm. One electrode was used for induction of feeding reaction and the other electrode was used for concurrent stimulation (with the subthreshold current) and subsequent electrolytic lesioning of the contralateral VTA. It was found that both contralateral stimulation and subsequent lesion performed through the same electrode facilitated a feeding response that manifested as a decrease in the reaction's threshold and a leftward shift of the latency-frequency curve. The paradoxical similarity of the effects of the stimulation and lesion is discussed in terms of functional organization of the mesocorticolimbic system and adaptive changes in dopaminergic transmission.
3
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Activation of tachykinin system in the pedunculopontine tegmental nucleus suppresses hippocampal theta rhythm in urethane-anesthetized rats

100%
Leszkowicz E., Trojniar W.
Acta Neurobiologiae Experimentalis
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2005
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vol. 65
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issue 3
373-386
EN
The pedunculopontine tegmental nucleus (PPN) is one of the reticular generators of the hippocampal theta rhythm. The PPN neuronal circuitry related to theta generation involves its cholinergic, GABA-ergic and glutamatergic components. Here we provide data indicating that the PPN tachykinin system may also be a part of this circuitry. In the experimental model of the tail-pinch elicited hippocampal theta in urethane-anesthetized rats (implanted with bilateral recording electrodes in the stratum moleculare of the upper blade of the dentate gyrus and with injection cannula unilaterally inserted into the PPN) it was found that intra-PPN microinjection of Substance P (SP) and [d-Pro2, d-Phe7, d-Trp9]-Substance P (DPDPDT) caused suppression of the theta and enhancement of the delta activity in the hippocampal EEG. Accordingly, there was approximately a 50% (SP) -70% (DPDPDT) decline of the peak power in the theta frequency range and a decrease by 0.4 Hz in the corresponding peak frequency (DPDPDT only) in both hippocampi. The circuitry through which SP exerts its effect in the PPN can be only hypothetical at present. We suggest SP-evoked activation (either direct or indirect through the glutamatergic inputs) of the GABA interneurons which may tonically inhibit PPN outputs to the other theta-relevant structures.
4
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Modulation of hippocampal theta rhythm by the opioid system of the pedunculopontine tegmental nucleus

81%
Leszkowicz E., Kusmierczak M., Matulewicz P., Trojniar W.
Acta Neurobiologiae Experimentalis
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2007
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vol. 67
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issue 4
447-460
EN
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 micrograms) 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 micrograms), the addition of MF (5 micrograms) prolonged theta latency and shortened the duration of the theta. These effects of MF were blocked by naloxone (5 micrograms). The results obtained suggest that the PPN opioid system can enhance or suppress the hippocampal theta depending on the actual level of PPN activation.
5
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Effect of unilateral injection of MK-801 into the area of A10 cells on feeding evoked by stimulation of homologous area in the contralateral hemisphere

81%
Maliszewska-Scislo M., Trojniar T. W., Trojniar W.
Acta Neurobiologiae Experimentalis
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2000
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vol. 60
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issue 4
489-494
EN
It was found previously that unilateral electrolytic and 6-OHDA lesions of the ventral tegmental area (VTA) and unilateral intra-VTA injection of bicuculline resulted in facilitation of behavioral responses evoked by electrical stimulation of the symmetrical VTA area in the contralateral hemisphere. We postulated that ?the contralateral facilitation effect?, which may reflect the yet unexplored mechanism of immediate compensation after acute unilateral brain injury, is attributable to the A10 DA neurons and their regulatory inputs. The present study was aimed at examining the possible involvement of NMDA-mediated glutamatergic transmission in VTA in the ?contralateral facilitation effect?. The behavioral model of the VTA stimulation-induced feeding in rats was used. Latency to eat was measured as a function of stimulation frequency before and after unilateral intra-VTA injection of non-competitive NMDA receptors antagonist, MK-801, (doses 0.0, 1.25 and 2.5 mg). MK-801 caused a dose-dependent augmentation of feeding evoked by stimulation of the contralateral VTA, which manifested as a decrease in the reaction frequency threshold and a leftward shift of the latency/frequency curve. Dose 2.5 mg replicated the facilitatory effect of electrolytic and 6-OHDA lesions. The results are interpreted in terms of MK-801-evoked depression of excitatory glutamatergic tone over A10 DA cells and compensatory increase in DA release in the contralateral hemisphere.
6
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Effect of lateral hypothalmic lesion on sleep-waking pattern and EEG power spectra in the rat

81%
Jurkowlaniec E., Pracki T., Trojniar W., Tokarski J.
Acta Neurobiologiae Experimentalis
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1996
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vol. 56
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issue 1
249-253
EN
Bilateral, electrolytic lesion of the lateral hypothalamus (LH) in rats produces hyposomnia and qualitative EEG changes which are difficult to assess by convencional visual inspections of electroencephalograms. In the present study the spectral analysis of EEG was applied in LH-lesioned rats and confronted with standart visual scoring method. One-hour samples of hippocampal and cortical EEG were taken from the light part of the circadian cycle before and after electrolytic or sham LH damage. In half of the LH-lesioned rats a power spectral analysis was performed using a Fast Fourier Transform routine at 1 Hz bands from 0.5 to 25 Hz; in the other half, as well as in the sham-lesioned group, EEG records were visually scored for the amount of waking, slow wave sleep and paradoxical sleep. Significant hyposomnia effects were found in LH-lesioned rats. Power spectral analysis of hippocampal EEG revealed a significant increase in power density at 4-6 Hz and reduction at 7-10, 14-17, 19-22 and 23-24 Hz. In neocortical EEG there was a significant increase in power density at 5-6 Hz band and reduction at 7-8 Hz. The results are discussed in the context of the effects of selective desrtuction of the specific neurotransmitter systems occupying the LH area.
7
Content available remote

Effect of unilateral ibotenate lesions of the ventral tegmental area on cortical and hippocampal EEG in freely behaving rats

81%
Jurkowlaniec E., Tokarski J., Trojniar W.
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EN
It was found previously that unilateral destruction of the ventral tegmental area (VTA) facilitated behavioral responses (exploration, eating) induced by electrical stimulation of the contralateral VTA. The same effect occurred after unilateral injections of pharmacological agents, which led to a decrease in dopaminergic transmission in the VTA. While trying to explain the mechanism behind this 'contralateral facilitation effect' in the present experiment we examined whether augmentation of function of the contralateral hemisphere would be reflected in cortical and hippocampal EEG changes in conscious rats. Unilateral, cytotoxic lesion of the VTA caused a bilateral decrease in neocortical and hippocampal EEG power during both exploratory sniffing and eating. Depression involved all the frequency bands in the prefrontal cortex, mainly in the hemisphere contralateral to the VTA lesion. In the hippocampus the depression was slightly more intense ipsilaterally, also involving all the frequency bands although to different degrees. The results indicate that the VTA is involved in the regulation of cortical and hippocampal activity during VTA-dependent behavioral activation, and that the 'contralateral facilitation effect' is concomitant with lateralized changes in EEG activity.
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