Effect of selective midbrain and diencephalic 5,7-dihydroxytryptamine lesions on serotonin content in individual preopticohypothalamic nuclei and on serum luteinizing hormone level

• Published in: Neuroendocrinology Vol. 31; no. 5; p. 309
• Main Authors: van de Kar, L D, Lorens, S A, Vodraska, A, Allers, G, Green, M, Van Orden, D E, Van Orden, 3rd, L S
• Format: Journal Article
• Language: English
• Published: Switzerland 01.01.1980
• Subjects: 5,7-Dihydroxytryptamine - pharmacology; Animals; Brain Stem - physiology; Castration; Catecholamines - metabolism; Hypothalamus - metabolism; Hypothalamus - physiology; Luteinizing Hormone - metabolism; Male; Mesencephalon - physiology; Raphe Nuclei - physiology; Rats; Serotonin - metabolism
• ISSN: 0028-3835
• DOI: 10.1159/000123093

Injection of the serotonin neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT), into the midbrain dorsal (DR) or median (MR) raphe nucleus of castrated and normal male rats was followed by measurement of serum luteinizing hormone (LH) level and the 5-hydroxytryptamine (5-HT) content of several hypothalamic and amygdaloid nuclei. Only the DR lesions lead to a significant decrease (42%) in serum LH level in normal rats. The elevated LH level in castrated animals was not affected by either lesion. The DR lesions were followed by 5-HT reductions only in the medial preoptic area, the arcuate and ventromedial hypothalamic nuclei, and in the basal and central amygdaloid nuclei. In contrast, the 5-HT reductions produced by MR lesions were much more widespread, being found in all nuclei assayed with the exception of the dorso- and ventromedial hypothalamic nuclei. In a second experiment, degeneration of serotonergic terminals in the ventromedial region of the hypothalamus following intradiencephalic injections of 5,7-DHT led to a significant decrease in serum LH level and a 5-HT reduction in the arcuate, ventromedial and dorsomedial hypothalamic nuclei. 5,7-DHT injections into the medial preoptic area and the anterior hypothalamic area did not affect serum LH level. These results suggest that a serotonergic pathway originating in the midbrain dorsal raphe nucleus and innervating the mediobasal hypothalamus has a stimulatory influence on LH secretion.