Morphine-induced inhibition of ovulation in normally cycling rats: neural site of action.
Intracerebral injection of morphine (3 micrograms/0.2 microliter of solvent) on the day of proestrus at 1200 hr bilaterally in the medial preoptic area (mPOA) and median eminence-arcuate (ME-ARC) region inhibited ovulation in the cycling female rats. The morphine antagonist, lethidrone (2 micrograms/0.2 microliter of solvent) when injected in the mPOA and ME-ARC region followed by intraperitoneal morphine (3 mg/100 g body weight) administration, was found to reverse the ovulation blocking action of this opiate. Implantation site at which morphine was effective in blocking ovulation were restricted to a narrow medial band encompassing the mPOA and ME-ARC region. Our data are consistent with the view that the endogenous opioid peptides in mPOA and ME-ARC region of the hypothalamus may be involved in the physiological regulation of the central neural events which lead to ovulation in the rat.
Lakhman
S S
SS
Neurophysiology and Neurochemistry Laboratory, School of Life Sciences, Guru Nanak Dev University, Amrit, India.
Singh
R
R
Kaur
G
G
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects*; D004347:Drug Interactions; D005260:Female; D008473:Median Eminence / Q000187:drug effects*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009269:Nalorphine / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects*; D011301:Preoptic Area / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains
D009020:Morphine; D009269:Nalorphine