{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T11:25:36Z","timestamp":1783596336076,"version":"3.55.0"},"reference-count":0,"publisher":"Bioscientifica","issue":"2","content-domain":{"domain":["journals.bioscientifica.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1988,5,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>The effects on sexual maturation of the opioid receptor antagonists naloxone and naltrexone were studied in the female rat. Neonatal treatment (days 1\u201310) with either naloxone (2\u00b75 mg\/kg at 6-h intervals) or naltrexone (20 or 50 mg\/kg per day) did not advance sexual maturation as judged by age and body weight at vaginal opening and first ovulation. After treatment with naltrexone (20 mg\/kg) first ovulation occurred 2\u00b73 days earlier than in saline-treated control rats but this could be attributed to a growth-stimulating effect of naltrexone; the effect was not observed with 50 mg\/kg. An effect of neonatal treatment with naloxone on serum LH levels was seen at 23 days of age (155\u00b136 (s.e.m.) vs 14\u00b14 \u03bcg LH\/1 in controls, P&amp;lt;0\u00b701), but not at 29 or 33 days of age, at 2 days before first ovulation nor at first pro-oestrus. There were no differences in the number of ova released at first oestrus, nor in the length of the first cycle. Neonatal treatment with naltrexone (50 mg\/kg per day) did not alter the response to treatment with human chorionic gonadotrophin at 28\u201331 days of age: ovulation of a mean of 7\u00b73 ova was induced on day 32 in both naltrexone- and saline-treated rats. Naltrexone treatment (four daily injections of 20 mg\/kg at 2-h intervals) at 28\u201332 days of age advanced first ovulation by 4\u00b74 days in about 40% of the rats.<\/jats:p>\n                  <jats:p>Short-term effects of naloxone and naltrexone treatment on LH secretion were studied in 15-day-old rats and a clear increase in serum LH concentration was seen 15 min after injection; LH levels were similar with the various doses of antagonist used (2\u00b75 and 20 mg naloxone\/kg; 2\u00b75, 20 and 50 mg naltrexone\/kg). At 30 min after injection LH levels were still maximal if the 2\u00b75 mg\/kg dose of either antagonist was used, whereas with the higher doses a significant (P&amp;lt;0\u00b701) decrease in the level of LH was observed, indicating a longer-lasting effect of the lower (2\u00b75 mg\/kg) dose of antagonist on LH secretion. No differences in effectiveness were seen between the supposedly short-lasting opioid receptor antagonist naloxone and the supposedly long-lasting antagonist naltrexone.<\/jats:p>\n                  <jats:p>It was concluded that neonatal treatment with the opioid antagonists naloxone and naltrexone did not specifically influence sexual maturation. The antagonists clearly increased LH secretion in short-term experiments. Treatment with naltrexone at 28\u201332 days of age advanced first ovulation in 40% of the rats, a result that is in agreement with a possible opiatergic influence on the gradually increasing LH release during the final phase of sexual maturation.<\/jats:p>\n                  <jats:p>The effects of the opioid antagonist naltrexone on the LH release mechanism did not parallel its reported long-lasting effects on nociceptive response, no long-lasting increase of LH release was seen, and the timecourse of the LH response was the same using the antagonists naloxone and naltrexone.<\/jats:p>\n                  <jats:p>J. Endocr. (1988) 117, 237\u2013243<\/jats:p>","DOI":"10.1677\/joe.0.1170237","type":"journal-article","created":{"date-parts":[[2008,12,11]],"date-time":"2008-12-11T17:52:58Z","timestamp":1229017978000},"page":"237-243","update-policy":"https:\/\/doi.org\/10.1530\/crossmarkpolicy-5","source":"Crossref","is-referenced-by-count":10,"title":["Effects of treatment with the opioid antagonists naloxone and naltrexone on LH secretion and on sexual maturation in immature female rats"],"prefix":"10.1530","volume":"117","author":[{"given":"H. M. A.","family":"Meijs-Roelofs","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P.","family":"Kramer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"416","container-title":["Journal of Endocrinology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/joe.bioscientifica.com\/view\/journals\/joe\/117\/2\/joe_117_2_013.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.bioscientifica.com\/joe\/article-pdf\/117\/2\/237\/97517\/joe_117_2_013.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/journals.bioscientifica.com\/joe\/article-pdf\/117\/2\/237\/97517\/joe_117_2_013.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T11:03:42Z","timestamp":1783595022000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.bioscientifica.com\/joe\/article\/117\/2\/237\/16145\/Effects-of-treatment-with-the-opioid-antagonists"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1988,5,1]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1988,5,1]]}},"URL":"https:\/\/doi.org\/10.1677\/joe.0.1170237","relation":{},"ISSN":["1479-6805","0022-0795"],"issn-type":[{"value":"1479-6805","type":"electronic"},{"value":"0022-0795","type":"print"}],"subject":[],"published":{"date-parts":[[1988,5,1]]}}}