Search

The hypothalamus is the most important region in the control of food intake and body weight. The ventromedial 'satiety center' and lateral hypothalamic 'feeding center' have been implicated in the regulation of feeding and energy homeostasis by various studies of brain lesions. Orexins(orexin A and orexin B) and melanin-concentrating hormone (MCH), whose intracerebroventricular injections increase food intake, are localized in the lateral hypothalamus and provide diffuse projections throughout the brain. Orexins and MCH neurons have a coextensive distribution, but are not colocalized. Orexins and MCH may affect feeding behavior through distinct neuronal pathways. We here describe the effect of orexins and MCH on feeding behavior from the physiological, neuroanatomical and molecular studies.

The hormonal patterns during menstrual cycle, which consist of cyclic alterations in gonadotropins, estradiol, and progesterone, are controlled by hypothalamic-pituitary-ovarian feedback mechanism. GnRH produced in hypothalamus acts on the pituitary cells to secrete FSH and LH, which stimulate the follicular development. The developed follicles secrete estradiol, progesterone, inhibin, activin, and follistatin. Estradiol and progesterone, at different concentrations and/or ratios, either positively or negatively control the feedback of hypothalamic-pituitary axis in regulating the secretion of GnRH, FSH and LH. Inhibin and follistatin selectively suppress, whereas activin enhances the secretion of FSH in the pituitary. Recently, various additional factors produced by the ovary have been identified to contribute to the follicular development by paracrine and/or autocrine regulation as well as to feedback on hypothalamic-pituitary unit.