Long-term imipramine treatment potentiates m-chlorophenylpiperazine-induced changes in prolactin but not corticosterone or growth hormone levels in rats.
Intravenous administration of m-chlorophenylpiperazine (m-CPP, a selective 5-HT agonist) to rats produced increases in plasma prolactin and corticosterone and a decrease in plasma growth hormone concentrations. Long-term but not short-term imipramine treatment potentiated m-CPP's effect on plasma prolactin, but not its effects on corticosterone or growth hormone. Short-term or long-term imipramine treatment did not produce significant changes in baseline levels of prolactin, corticosterone or growth hormone. These findings are compatible with development of functional supersensitivity of 5-HT receptors mediating prolactin release. Lack of potentiation of m-CPP's effects on corticosterone and growth hormone following long-term imipramine treatment suggests either differential regulation of these hormones by serotonergic and possibly other mechanisms, or different 5-HT receptor subtypes mediating the release of these hormones. Alternatively, adaptive changes in other aminergic neurotransmitter mechanisms such as the noradrenergic system may account for the differential effect of long-term imipramine treatment on m-CPP-induced neuroendocrine changes.
Aulakh
C S
CS
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20892.
Haass
M
M
Zohar
J
J
Wozniak
K M
KM
Hill
J L
JL
Murphy
D L
DL
D000818:Animals; D003345:Corticosterone / Q000097:blood*; D004357:Drug Synergism; D013006:Growth Hormone / Q000097:blood*; D007099:Imipramine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D010879:Piperazines; D011388:Prolactin; D013006:Growth Hormone; D007099:Imipramine; C015068:1-(3-chlorophenyl)piperazine; D003345:Corticosterone