Gonadal effects on food intake and adiposity: a metabolic hypothesis

In vivo cell nuclear binding of 17 beta-[3H]estradiol in rat adipose tissues

Rat adipose tissues contain high-affinity, hormone-specific cytoplasmic estrogen receptors. If adipose tissues are actually estrogen target tissues, then it should be possible to demonstrate in vivo binding and retention of 17 beta-[2H]estradiol in adipose tissue cell nuclei, the putative subcellular site of steroid action. Gonadectomized rats were given an intravenous injection of 40 microCi (0.11 microgram) 17 beta-[2,4,6,7-3H]estradiol. Animals were then killed, and cell nuclei were isolated from hypothalamus and various fat pads. Cell nuclear levels of radioactivity peaked at 1 h in both hypothalamus and parametrial adipose tissue, but the peak cell nuclear concentration in the fat pad was more than twice that in hypothalamus. At 1 h, 89% of the adipose tissue nuclear radioactivity migrated with 17 beta-estradiol on thin-layer plates. Radioactivity was retained in cell nuclei for more than 6 h in both tissues. This cell nuclear binding was estrogen specific. Pretreatment with radioinert estrogens (17 beta-estradiol or R 2858) abolished cell nuclear 17 beta-[3H]estradiol uptake, but other steroids (progesterone, corticosterone, and 5 alpha-dihydrotestosterone) were without effect. Cell nuclear binding was found in all fat pads studied in both males and females. Levels were highest in parametrial (females) and epididymal (males) fat pads, the depots with the highest concentration of cytoplasmic estrogen receptor. There were no sex differences in cell nuclear binding. Taken together these findings provide strong support for the contention that 17 beta-estradiol could affect lipid metabolism and body fat content in part by direct action on adipose tissues.

Relationship among reproductive variables, sucrose taste reactivity and feeding behavior in humans

Magnitude-estimation of sucrose pleasantness and sweetness, and feeding behavior, were investigated in female and male college students. The subjects were individually tested five times over a five-week period. Female test intervals were scheduled to include the menses, pre-ovulatory, and luteal phases of the menstrual cycle. The data were analyzed by gender, length of menses, and phase of the menstrual cycle. The results of these analyses were consistent for both the sucrose taste reactivity tests and feeding tests. Male and long-menses females exhibited similar response patterns; and their pattern was significantly different from that of the short-menses females. The mean log pleasantness ratings of the males and long-menses females were significantly smaller than those of the short-menses females. Furthermore, both long-menses females and males behaved similarly in a time-limited surreptitious feeding test. They consumed significantly more food than did short-menses females. Phase of the menstrual cycle did not alter pleasantness reponse patterns, but there was one phase effect in the feeding tests. Luteal phase intake of short-menses females was elevated relative to that of the menses phase. These findings demonstrate that reproductive variables participate in the control of human regulatory behaviors.