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Evidence for the hypothesis that brain-opioids mediate social affect and social attachments is summarized. Opiates and opioids are very effective in reducing social separation-induced distress vocalizations (DVs), in puppies, young guinea pigs and chicks, while opiate antagonists can increase DVs. In studies of specific social behaviors in rodents, morphine(More)
When young animals are separated from their normal social environment in groups they distress vocalize (DV) less than when isolated alone. Opioid blockade with naloxone (1 mg/kg peripherally, and 1 microgram centrally) increased crying more in group tested chicks than individually tested ones. The serotonin receptor blocking agent methysergide and the(More)
All the opiate-like peptides we tested (Met-enkephalin, (D-Ala2)-Met-enkephalin-NH2, beta-endorphin, (D-Ala2)-beta-endorphin, (D-Ala2)-alpha-endorphin, (D-Ala2)-gamma-endorphin) were capable of reducing distress vocalizations (DV's) in socially-isolated chicks when injected into the vicinity of the fourth ventricle in doses as low as 100 picomoles. All of(More)
Female rats with lesions of the ventromedial hypothalamus (VMH) were ovariectomized during the static obese stage after body weight levels had stabilized. Following ovariectomy, rats with VMH lesions showed smaller increases in food intake and less body weight gain than non-lesioned controls ovariectomized at the same time. Subsequently, the effects of(More)
Activity, O2 consumption, and body composition were measured in female rats with lesions of the ventromedial hypothalamus (VMH). One group of lesioned rats was food restricted to maintain body weights at control levels. O2 consumption of these food-restricted VMH-lesioned rats was 13% lower than that of nonlesioned rats. About half this energy savings(More)
Weight loss through caloric restriction produces compensatory reductions in the whole body energy expenditure of normal rats. The present experiment determined whether rats who had become obese after ventromedial hypothalamic (VMH) lesions displayed this metabolic defense of body weight. Obese VMH-lesioned and normal-weight control female rats were assigned(More)
Intraventricular injections of beta-endorphin, gamma-endorphin and alpha-endorphin were demonstrated to reduce isolation-induced distress vocalization on 2-4 day old chicks in a dose response manner at doses as small as 12.5 picomoles (pmol). beta-Endorphin was more potent than the other peptides and morphine, while Met-enkephalin was without effect.(More)
In a series of experiments designed to assess the effects of alpha-MSH on various motivational processes, it was observed that the hormone can slightly decrease food intake and increase water consumption during the first hr after administration in rats. alpha-MSH also modified avoidance behavior in 1- and 3-day-old chicks, but there were no reliable effects(More)
The effects of ventromedial hypothalamic (VMH) lesions were studied in female rats made diabetic with streptozotocin that were given twice daily injections of protamine zinc insulin (0.75 mu/100g/day) and in non-diabetic animals of the same sex. Hyperphagia resulted from VMH lesions in both diabetic animals whose insulin levels were controlled and in(More)