Effects of chronic mild food restriction on behavior and the hypothalamic malonyl-CoA signaling pathway.

Depression induces anorexia, leading to suppressed feeding behaviors and energy intake. Previously, we revealed that chronic social defeat induced a mild suppression of feeding in rats with elevated levels of hypothalamic malonyl-CoA which regulates feeding. Therefore, we attempted to elucidate the effects of chronic mild food restriction on behavior and on hypothalamic malonyl-CoA. The chronic mild food restricted rats were fed a restricted diet approximately 80% to 90% amount of diet compared to the control for 5 weeks. Ratios of restriction were adjusted with feed consumption in the chronic social defeat stressed rats. Chronic mild food restricted rats exhibited a suppression of body weight gain similar to that of the chronic social defeat stressed rats. Also these rats showed increased time spent in the center area of an open field (OF), prolonged immobility time in forced swim, increased phosphorylation of hypothalamic adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase and a decreased concentration of hypothalamic malonyl-CoA. Weight of the adrenal glands, locomotion in an OF, mitogen-activated protein kinase cascade and calcium/calmodulin-dependent protein kinases II in the hippocampus were not affected by chronic mild food restriction. Our findings suggest that chronic mild food restriction activates AMPK following a decreased hypothalamic malonyl-CoA.

Anorexic behavior and elevation of hypothalamic malonyl-CoA in socially defeated rats.

Suppression of body weight and eating disorders, such as anorexia, are one of the major symptoms of psychiatric disorders such as depression. However, the mechanisms of weight loss and reduced appetite in depressive patients and in animal models of depression are largely unknown. In this study, we characterized the mechanism of anorexia resulting from depression using socially defeated rats as an animal model of depression. Socially defeated rats showed suppressed body weight gain, enlarged adrenal glands, decreased home cage activity, decreased food intake, and increased immobility in the forced swim test. These results are representative of some of the core symptoms of depression. Simultaneously, we observed decreased levels of phosphorylated AMP-activated protein kinase (AMPK) and acetyl-coenzyme A (CoA) carboxylase (ACC) and increased levels of malonyl-CoA in the hypothalamus of socially defeated rats. Hypothalamic malonyl-CoA controlled feeding behavior and elevation of malonyl-CoA in the hypothalamus induced inhibition of food intake. Our findings suggest that the suppression of body weight gain caused by social defeat stress is caused by anorexic feeding behavior via an increased concentration of malonyl-CoA in the hypothalamus.

Improvement of bone strength and dermal thickness due to dietary edible bird's nest extract in ovariectomized rats.

Oral administration of edible bird's nest extract (EBNE) improved bone strength and calcium concentration in the femur of ovariectomized rats. Dermal thickness was also increased by EBNE supplementation, whereas EBNE administration did not affect the serum estradiol concentration. These results suggest that EBNE is effective for the improvement of bone loss and skin aging in postmenopause all women.