TY - JOUR
T1 - Repeated cocaine exposure inhibits the adrenocorticotropic hormone response to the serotonin releaser d-fenfluramine and the 5-HT1A agonist, 8-OH-DPAT
AU - Levy, A. D.
AU - Li, Q.
AU - Van de Kar, L. D.
N1 - Funding Information:
Acknowledgements--The authors would like to thank Kayoko Kunimoto and Joseph Yracheta for their excellent technical assistance. We also appreciate the donation of cocaine by the National Institute of Drug Abuse, d-fenfluramine by Servier, fluoxetine HCI by the Eli Lilly Co., and prolactin antiserum and purified prolactin for radioimmunoassay from NIDDK. Supported by USPHS grants DA04865 and MH48512, the American Heart Association of Metropolitan Chicago, and the Loyola University Chicago Neuroscience and Aging Institute.
Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 1994
Y1 - 1994
N2 - The influence of cocaine exposure on serotonergic neurons and postsynaptic 5-HT1A receptor-mediated responses was evaluated by measuring neuroendocrine responses to a serotonin (5-HT) releaser or a 5-HT1A agonist. Male rats received cocaine (15 mg/kg, i.p.) or saline twice daily for 7 days. Forty-two hr after the final cocaine injection, the 5-HT releaser d-fenfluramine (0, 0.2, 0.6, 2, or 5 mg/kg, i.p.) or the 5-HT1A agonist, 8-OH-DPAT (0, 10, 50, 200 or 500 μg/kg, s.c.) were administered. Blood samples were then collected for analysis of plasma ACTH, prolactin, and renin concentrations. The ACTH responses to d-fenfluramine and 8-OH-DPAT were inhibited in cocaine pretreated rats. However, the prolactin responses to d-fenfluramine and 8-OH-DPAT were not significantly modified by cocaine exposure. Additionally, the renin response to d-fenfluramine was unaltered by repeated cocaine administration, while 8-OH-DPAT did not alter renin secretion in either pretreatment group. In contrast to published reports which show that cocaine exposure produces supersensitive 5-HT2A and/or 5-HT2C receptor-mediated responses, the present data suggest that repeated cocaine exposure produces subsensitivity to at least some postsynaptic 5-HT1A receptors. Cocaine-induced deficits in the ACTH response to 5-HT releasers may reflect 5-HT1A receptor subsensitivity, but presynaptic deficits cannot be excluded. Examination of the ACTH response to 5-HT1A agonists may represent a valuable approach to deermine deficits in 5-HT function in human cocaine abusers.
AB - The influence of cocaine exposure on serotonergic neurons and postsynaptic 5-HT1A receptor-mediated responses was evaluated by measuring neuroendocrine responses to a serotonin (5-HT) releaser or a 5-HT1A agonist. Male rats received cocaine (15 mg/kg, i.p.) or saline twice daily for 7 days. Forty-two hr after the final cocaine injection, the 5-HT releaser d-fenfluramine (0, 0.2, 0.6, 2, or 5 mg/kg, i.p.) or the 5-HT1A agonist, 8-OH-DPAT (0, 10, 50, 200 or 500 μg/kg, s.c.) were administered. Blood samples were then collected for analysis of plasma ACTH, prolactin, and renin concentrations. The ACTH responses to d-fenfluramine and 8-OH-DPAT were inhibited in cocaine pretreated rats. However, the prolactin responses to d-fenfluramine and 8-OH-DPAT were not significantly modified by cocaine exposure. Additionally, the renin response to d-fenfluramine was unaltered by repeated cocaine administration, while 8-OH-DPAT did not alter renin secretion in either pretreatment group. In contrast to published reports which show that cocaine exposure produces supersensitive 5-HT2A and/or 5-HT2C receptor-mediated responses, the present data suggest that repeated cocaine exposure produces subsensitivity to at least some postsynaptic 5-HT1A receptors. Cocaine-induced deficits in the ACTH response to 5-HT releasers may reflect 5-HT1A receptor subsensitivity, but presynaptic deficits cannot be excluded. Examination of the ACTH response to 5-HT1A agonists may represent a valuable approach to deermine deficits in 5-HT function in human cocaine abusers.
KW - ACTH
KW - Serotonin
KW - cocaine
KW - neuroendocrine
KW - prolactin
KW - renin
UR - http://www.scopus.com/inward/record.url?scp=0028289534&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028289534&partnerID=8YFLogxK
U2 - 10.1016/0028-3908(94)90063-9
DO - 10.1016/0028-3908(94)90063-9
M3 - Article
C2 - 7984271
AN - SCOPUS:0028289534
SN - 0028-3908
VL - 33
SP - 335
EP - 342
JO - Neuropharmacology
JF - Neuropharmacology
IS - 3-4
ER -