Central neuroanatomical systems involved in the regulation of food intake in birds and mammals.

The neural regulation of food intake seems to be quite similar in birds and mammals. The ventromedial hypothalamic syndrome produced by lesions within the mediobasal hypothalamus of both birds and mammals is composed of several independent physiological and behavioral changes. Other neural sites known to be important in mammals for regulating food intake need to be examined in birds including the paraventricular nucleus, nucleus tractus solitarius and parabrachial nucleus. Members of the opioid and pancreatic polypeptide families are effective in stimulating food intake in avian species. Both prolactin and growth hormone are also efficacious in stimulating food intake. In contrast, cholecystokinin inhibits food intake when administered intracerebroventricularly. The autonomic and endocrine hypothesis developed to explain obesity in mammals appears to be quite applicable to genetic strains of commercial birds selected for meat production. Specifically the commercial broiler appears to display an imbalance of the autonomic nervous system. The parasympathetic nervous system dominates as a consequence of intense genetic selection for growth rate.