Neurotensin-induced activation of hypothalamic dopaminergic neurons is accompanied by a decrease in pituitary secretion of prolactin and alpha-melanocyte-stimulating hormone.
The effects of neurotensin on the activity of hypothalamic tuberoinfundibular and periventricular-hypophysial dopaminergic (DA) neurons, and on the secretion of pituitary hormones that are tonically regulated by these neurons (i.e. prolactin and alpha-melanocyte-stimulating hormone [alpha MSH], respectively) were examined in estrogen-primed ovariectomized rats. The activity of tuberoinfundibular and periventricular-hypophysial DA neurons was estimated by measuring concentrations of the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the terminals of these neurons in the median eminence and intermediate lobe of the posterior pituitary, respectively. Intracerebroventricular administration of neurotensin caused a dose- and time-related increase in DOPAC concentrations in both the median eminence and intermediate lobe, and a concurrent decrease in plasma levels of prolactin and alpha MSH. These results suggest that neurotensin-induced inhibition of secretion of prolactin and alpha MSH from the pituitary may be due to the stimulatory action of this neuropeptide on the release of dopamine from tuberoinfundibular and periventricular-hypophysial neurons.
Pan
J T
JT
Department of Pharmacology and Toxicology, Michigan State University, E. Lansing 48824.
Tian
Y
Y
Lookingland
K J
KJ
Moore
K E
KE
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007276:Injections, Intraventricular; D008473:Median Eminence / Q000187:drug effects* / Q000378:metabolism; D009074:Melanocyte-Stimulating Hormones / Q000097:blood / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009496:Neurotensin / Q000494:pharmacology*; D010904:Pituitary Gland, Posterior / Q000378:metabolism; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats
D015102:3,4-Dihydroxyphenylacetic Acid; D009496:Neurotensin; D011388:Prolactin; D009074:Melanocyte-Stimulating Hormones; D004298:Dopamine