Changes of beta-endorphin and somatostatin concentrations in different hypothalamic areas of female rats after chronic starvation.
To study the effect of starvation on hypothalamic beta-endorphin and somatostatin (SRIF) concentrations in relation to starvation induced anestrus, groups of 8 rats were fed 50% of their normal daily chow consumption. Rats were sacrificed after 4, 8, 12, and 16 days during diestrus or anestrus. beta-endorphin concentrations decreased in the preoptic suprachiasmatic area (0.52 +/- 0.13 vs 0.21 +/- 0.05 ng/mg tissue wet weight) and increased in the posterior hypothalamus (0.31 +/- 0.06 vs 0.57 +/- 0.11 ng/mg) after 4 days of starvation. No significant change occurred in the arcuate nucleus or in the median eminence. On day 8 and 12 of starvation, beta-endorphin was unaltered in all areas compared to controls. Vaginal smears showed constant diestrus in a significant number of rats (5 out of 8) after 12 days. beta-endorphin concentrations in the arcuate nuclei of these rats were significantly reduced on day 16 (1.00 +/- 0.33 vs 0.30 +/- 0.11 ng/mg). The SRIF levels changed only in the median eminence with increased concentrations on day 12 (45.2 +/- 8.4 vs 79.5 +/- 14.8 ng/mg). At this time serum levels of luteinizing hormone (LH), prolactin (PRL), and growth hormone (GH) were significantly reduced. The results indicate that changes in hypothalamic beta-endorphin accompany the events leading to starvation induced anestrus.
D000780:Anestrus; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D004031:Diestrus; D004723:Endorphins / Q000378:metabolism*; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D007032:Hypothalamus, Anterior / Q000378:metabolism; D007034:Hypothalamus, Posterior / Q000378:metabolism; D008473:Median Eminence / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism*; D013217:Starvation / Q000378:metabolism*; D001615:beta-Endorphin
D004723:Endorphins; D013004:Somatostatin; D001615:beta-Endorphin