Effect of cocaine injections on the neuroendocrine response to the serotonin agonist MK-212.
This study was undertaken to examine whether several of the hormones that can be released by activation of serotonin receptors will be affected by long-term cocaine administration. Male rats received cocaine injections (15 mg/kg, IP) twice daily for 7 days. Forty-two hr after the last cocaine injection, the rats were challenged with increasing doses (0, 1, 5, 10 mg/kg, IP) of the 5-HT1/5-HT2 agonist MK-212 (6-chloro-2-[1-piper-azinyl]-pyrazine). The following observations were made: (1) cocaine reduced the rate of body weight gain; (2) cocaine inhibited the stimulatory effect of MK-212 on plasma vasopressin, oxytocin, and prolactin concentrations and on plasma renin activity and concentration; (3) cocaine did not inhibit the stimulatory effect of MK-212 on plasma ACTH or corticosterone concentrations. The data indicate that a wide-spectrum 5-HT (serotonin) agonist such as MK-212 can reveal differential neuroendocrine responses. This effect could be related to cocaine-induced changes in the different 5-HT receptor subtypes that regulate the secretion of these hormones.
Van de Kar
L D
LD
Department of Pharmacology, Stritch School of Medicine, Loyola University of Chicago, Maywood, IL 60153.
Rittenhouse
P A
PA
O'Connor
P
P
Palionis
T
T
Brownfield
M S
MS
Lent
S J
SJ
Carnes
M
M
Bethea
C L
CL
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001143:Arousal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology*; D003345:Corticosterone / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006728:Hormones / Q000097:blood*; D007274:Injections, Intraperitoneal; D008297:Male; D009490:Neurosecretory Systems / Q000187:drug effects*; D010121:Oxytocin / Q000097:blood; D011388:Prolactin / Q000097:blood; D011719:Pyrazines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000097:blood; D009435:Synaptic Transmission / Q000187:drug effects; D014667:Vasopressins / Q000097:blood
D006728:Hormones; D011719:Pyrazines; D014667:Vasopressins; D010121:Oxytocin; C014896:6-chloro-2-(1-piperazinyl)pyrazine; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D012083:Renin; D003042:Cocaine; D003345:Corticosterone