Effect of ovarian and exogenous hormones on defended body weight, actual body weight, and the paradoxical hoarding of food by female rats.
Normally cycling female rats maintained on a free diet and showing the usual female pattern of hoarding behaviour (greater than 5 pellets/day) underwent bilateral ovariectomy or sham surgery. Body weights after ovariectomy showed a rapid increase for four postoperative weeks, paralleled by a sharp increase in food hoarding. During the fifth and sixth weeks, when body weights had stabilised at a higher level, hoarding activity reverted to preoperative levels. Daily intramuscular administration of oestradiol benzoate (2.0 micrograms or 25 micrograms/day for five days) counteracted the increases in body weight and hoarding activity. Progesterone (0.5 mg/day) and testosterone (0.5 mg/day) were without significant effect. The increased hoarding activity after ovariectomy is an indication of a rise in the defended level of body weight, and supports earlier suggestions that oestrogen lowers the physiological setting about which body weight is regulated. Paradoxical findings that non-deprived intact females hoard more, not less, than males are considered in the light of nonregulatory constraints on body weight which would affect hoarding by shifting body weights above, or below regulated levels.
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects*; D002369:Castration; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D009115:Muridae; D011374:Progesterone / Q000494:pharmacology*; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone; D011374:Progesterone; D004958:Estradiol