Abstract
In the rat brain, the dorsal raphe nucleus contains a large proportion of serotoninergic neurons, which are mostly regulated by somato-dendritic 5-HT 1A autoreceptors. This nucleus also possesses intracellular glucocorticoid receptors (GR), which may be involved in the well established modulation of serotonin (5-hydroxytryptamine, 5-HT) metabolism by glucocorticoids. Control by corticosteroids of 5-HT 1A receptor-mediated inhibitory control of the firing of serotoninergic neurons in the dorsal raphe nucleus was investigated using an in vitro electrophysiological approach. The spontaneous firing rate of serotoninergic neurons recorded in brain stem slices and its inhibition due to 5-HT 1A autoreceptor stimulation by 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) were similar in adrenalectomized rats and sham-operated animals. In vitro pretreatment with corticosterone (30–100 nM) significantly reduced 8-OH-DPAT-induced inhibition of the 5-HT cell discharge in slices from adrenalectomized rats. This effect could be prevented by the GR antagonist, 11β-(4-dimethyl-amino-phenyl)-17β-hydroxy-17α-(prop-1-ynyl)estra-4,9-dien-3-one (RU 38486, 30 nM), and mimicked by the GR agonist, 11β,17β-dihydroxy-6-methyl-17α(prop-1-ynyl)androsta-1, 4,6-trien-3-one (RU 28362,500 nM). In contrast, the mineralocorticoid receptor (MR) agonist, aldosterone (10 nM), did not alter 8-OH-DPAT-induced inhibition in tissues from adrenalectomized animals. Complementary autoradiographic experiments showed that [ 3H]8-OH-DPAT specific binding to 5-HT 1A sites in the dorsal raphe nucleus (and the hippocampus) was not significantly altered following adrenalectomy and exposure of brain stem slices to corticosterone. These data suggest that GR are involved in the suppressive effects of high levels of corticosterone on the 5-HT 1A receptor-dependent regulation of 5-HT neuronal activity in the rat dorsal raphe nucleus.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
