Effect of selective midbrain and diencephalic 5,7-dihydroxytryptamine lesions on serotonin content in individual preopticohypothalamic nuclei and on serum luteinizing hormone level.
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.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D002369:Castration; D002395:Catecholamines / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D011903:Raphe Nuclei / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000378:metabolism*
D002395:Catecholamines; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D007986:Luteinizing Hormone