Actions of 5‐hydroxytryptamine and 5‐HT_1A receptor ligands on rat dorso‐lateral septal neurones in vitro

Abstract

1 The actions of 5-hydroxytryptamine (5-HT) and some 5-HTA receptor ligands on neurones in the rat dorso-lateral septal nucleus were recorded in vitro by intracellular recording techniques.2 In the presence of tetrodotoxin (1 tiM) to block any indirect effects, bath application of 30 AM) hyperpolarized the neurones in a concentration-dependent manner and reduced membrane resistance. The hyperpolarization did not exhibit desensitization and was sometimes followed by a small depolarization. 6 The 5-HT2/5-HTlc receptor antagonist, ketanserin (3 jiM) and the 5HT3 receptor antagonist, tropisetron (3 tiM) did not antagonize the 5-HT-induced hyperpolarizations; however, ketanserin blocked the depolarization which sometimes followed the hyperpolarization. 7 It is concluded that the 5-HT-induced membrane hyperpolarization of rat dorso-lateral septal neurones is mediated by 5-HTA receptors.

The theta‐related firing activity of parvalbumin‐positive neurons in the medial septum‐diagonal band of broca complex and their response to 5‐HT1A Receptor stimulation in a rat model of Parkinson's disease

“…In the present study, systemic and local administration of 5‐HT 1A receptor agonist 8‐OH‐DPAT inhibited the firing rate of all the PV‐positive neurons examined in the MS‐DB of sham‐operated rats during hippocampal theta rhythm, and these effects were reversed by the selective 5‐HT 1A receptor antagonist WAY‐100635, indicating that these are 5‐HT 1A receptor‐mediated effects. The present results are supported by the fact that the in vitro recordings of septal neurons in brain slices have revealed that activation of 5‐HT 1A receptors hyperpolarizes the neurons and reduces GABA release from GABAergic neurons (Van den Hooff and Galvan, ; Fink and Gothert, ), and consistent with the well‐established role of 5‐HT 1A receptors in the control of neuronal firing of other brain areas. Therefore, the decreased firing rate of PV‐positive neurons in the MS‐DB induced by systemic administration of 8‐OH‐DPAT most likely reflects the direct activation of 5‐HT 1A receptors in the neurons examined.…”

The Modulatory Role of the Lateral Septum on Neuroendocrine and Behavioral Stress Responses

“…It was shown previously that LS 5-HT 1A receptors were located primarily on calbindin-positive neurons, indicative for septal GABAergic interneurons ( Aznar et al , 2003 ; Lüttgen et al , 2005 ). Moreover, electrophysiological experiments have established that septal 5-HT 1A receptor activation causes neuronal hyperpolarization ( Joëls et al , 1987 ; Van den Hooff and Galvan, 1992 ). Thus, it is conceivable that a reduced 5-HT function in the LS either during psychological stress exposure ( Kirby et al , 1995 ; Ebner et al , 2008 ) or after 5-HT 1A receptor blockade is associated with an enhanced intraseptal inhibitory function (presumably via GABAergic interneurons).…”

Role of tandospirone, a 5-HT1A receptor partial agonist, in the treatment of central nervous system disorders and the underlying mechanisms

“…5-HT1A receptor agonists are one sort of the ligands which is able to activate the 5-HT1A receptors. According to different intrinsic activities, 5-HT1A agonists are clarified in two categories, namely full agonists such as 8-OH-DPAT, F-11440 and flesinoxan, as well as partial agonists such as ipsapirone, gepirone, buspirone and tandospirone [ 17 – 20 ]. Tandospirone is highly potent among partial agonists of 5-HT1A receptor and has a K i value of 27 ± 5 nM.…”