The Pedunculopontine nucleus (Pedunculopontine tegmental nucleus, PPTN) is considered one of the key elements of the reticular activating system (RAS)[1]. It is located in the mesencephalic tegmentum just caudal to the red nucleus and dorsal to the substantia nigra; Laterally it is surrounded by the medial lemniscus and medially by fibers of the superior cerebellar peduncle[2]. PPTN has a cluster of cells that exhibit a wide heterogeneity in terms of their neurochemical nature, their discharge properties, and their connectivity[3]. Based upon this heterogeneity, the human PPTN has been subdivided into two divisions: 1) Pars dissipata, where GABAergic neurons predominate and is positioned throughout the rostrocaudal extent of the nucleus, and 2) Pars compacta, located in the
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The γ-aminobutyric acid (GABA) is believed to have major inhibitory effects in cardiovascular regulation systems [14-16]. GABAa and GABAb are clearly known GABA receptor subtypes. While GABAb receptors have inhibit neuronal activity through G-protein-coupled second-messenger systems[17], GABAA receptors are ligand-gated chloride ion channels. A variety of important drugs could affect GABAa receptors function. Reports indicate that these drugs, by interacting with several distinct binding sites at these receptors, could allosterically modulate GABA-induced chloride ion flux[18]; bicuculline has been demonstrated to act as an antagonist agent on GABAa receptors[19-21].
The regulatory role of GABAergic system on central cardiovascular functions in RVLM, CVLM, NTS, and PVN has been investigated[22-26] but it’s never been elucidated in PPTN. The present study was aimed to study the cardiovascular responses of the PPTN nucleus to microinjection of GABA receptors antagonist, bicuculline, in anesthetized rats. We also study the effect of Atropine perfusion on cardiovascular response caused by injection of
The γ-aminobutyric acid (GABA) is believed to have major inhibitory effects in cardiovascular regulation systems [14-16]. GABAa and GABAb are clearly known GABA receptor subtypes. While GABAb receptors have inhibit neuronal activity through G-protein-coupled second-messenger systems[17], GABAA receptors are ligand-gated chloride ion channels. A variety of important drugs could affect GABAa receptors function. Reports indicate that these drugs, by interacting with several distinct binding sites at these receptors, could allosterically modulate GABA-induced chloride ion flux[18]; bicuculline has been demonstrated to act as an antagonist agent on GABAa receptors[19-21].
The regulatory role of GABAergic system on central cardiovascular functions in RVLM, CVLM, NTS, and PVN has been investigated[22-26] but it’s never been elucidated in PPTN. The present study was aimed to study the cardiovascular responses of the PPTN nucleus to microinjection of GABA receptors antagonist, bicuculline, in anesthetized rats. We also study the effect of Atropine perfusion on cardiovascular response caused by injection of