title: Delayed suppression of serum luteinizing hormone after naloxone treatment in neonatal female rats.
abstract: In female neonatal rats, opiate receptor blockade markedly raises serum luteinizing hormone (LH) levels. The LH effect of acute treatment with opiate antagonists is apparently brief in older rats; however, age-related differences in antagonist pharmacokinetics may result in different LH response patterns. The duration of LH response to naloxone (NAL) and naltrexone (NTX) was examined in 5 day-old (d.o.) female rats and compared to the duration of analgesia blockade. The rise in serum LH following opiate receptor blockade in 5 d.o. rats was of similar duration to that previously observed in older animals and much briefer than blockade of analgesia. Furthermore, neonatal rats exhibited a delayed suppression of LH 6 hr following NAL, but not NTX, treatment. Stimulation and later suppression of LH were still observed after five repetitive NAL treatments at 6 hr intervals.
authors.affiliation: Department of Pharmacology, Duke University Medical Center, Durham, NC 27710.
authors.forename: E A
authors.initials: EA
authors.lastname: Field
authors.forename: C M
authors.initials: CM
authors.lastname: Kuhn
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D009020:Morphine / Q000037:antagonists & inhibitors; D009270:Naloxone / Q000494:pharmacology*; D009271:Naltrexone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D013997:Time Factors
chemical_list: D009270:Naloxone; D009271:Naltrexone; D009020:Morphine; D007986:Luteinizing Hormone