{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T13:54:14Z","timestamp":1778162054810,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2008,4,1]],"date-time":"2008-04-01T00:00:00Z","timestamp":1207008000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2008,4,1]],"date-time":"2008-04-01T00:00:00Z","timestamp":1207008000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Neuroendocrinology"],"abstract":"<jats:p>Immunoreactive \u03b2-endorphin (ir-\u03b2-END) concentrations were measured in the hypophysial portal plasma of the male rat under urethane anesthesia. On the basis of immunochemical studies and gel fitration chromatography it appears that ir-\u03b2-END in rat hypophysial portal plasma is primarily \u03b2-endorphin (\u03b2-END) and not \u03b2-lipotropin (\u03b2-LPH). In addition, much of the ir-\u03b2-END in portal plasma may be of pituitary origin since acute hypophysectomy resulted in approximately an 80% decrease in the portal plasma concentration of ir-\u03b2-END. Nevertheless, in anesthetized animals that had been hypophysectomized acutely, portal plasma concentrations of ir-\u03b2-END were still 5 times those in systemic plasma, indicative of hypothalamic secretion of the peptide. The administration of morphine sulfate (3 mg\/kg, i.v.) resulted in a decrease of ir-\u03b2-END concentrations from 3,157 \u00b1 547 pg\/ml to 1,044 \u00b1 250 pg\/ml. This effect was blocked by naltrexone (1 mg\/kg, s.c.) pretreatment. Capsaicin (10 \u00b5g), which, when infused into the lateral cerebral ventricle of the rat, has been shown to decrease the amount of \u03b2-END in the hypothalamus, but not elsewhere in the central nervous system, selectively decreased the concentration of ir-\u03b2-END in portal plasma without changing systemic ir-\u03b2-END concentrations. These studies indicate that ir-\u03b2-END in portal plasma is probably \u03b2-END which is derived from neurons in the hypothalamus. Moreover, it is concluded that the regulation of the release of ir-\u03b2-END from these neurons involves opiate receptor mechanisms. The inhibitory influence of opiates on ir-\u03b2-END secretion may be indicative of a classical feedback regulation of ir-\u03b2-END-containing neurons.<\/jats:p>","DOI":"10.1159\/000124589","type":"journal-article","created":{"date-parts":[[2008,4,2]],"date-time":"2008-04-02T11:56:21Z","timestamp":1207137381000},"page":"611-617","source":"Crossref","is-referenced-by-count":25,"title":["Morphine or Capsaicin Administration Alters the Secretion of Beta-Endorphin into the Hypophysial Portal Vasculature of the Rat"],"prefix":"10.1159","author":[{"given":"James I.","family":"Koenig","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Herbert Y.","family":"Meltzer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gary A.","family":"Gudelsky","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2008,4,1]]},"container-title":["Neuroendocrinology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000124589","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T19:12:27Z","timestamp":1777662747000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000124589"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2008,4,1]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000124589","archive":["Portico"],"relation":{},"ISSN":["0028-3835","1423-0194"],"issn-type":[{"value":"0028-3835","type":"print"},{"value":"1423-0194","type":"electronic"}],"subject":[],"published":{"date-parts":[[2008,4,1]]}}}