ENDOCRINE FUNCTION OF NEUROPEPTIDE-Y KNOCKOUT MICE

Among its many proposed functions, neuropeptide Y (NPY) is thought to modulate the hypothalamic-pituitary axis. Specifically, increased hypo thalamic NPY signaling may be critical in mediating the neuroendocrine response to fasting. To determine the consequences of NPY deficiency on endocrine physiology, multiple hormones were quantitated in wildtyp e and NPY-knockout mice under fed and fasted conditions. Serum concent rations of leptin, corticosterone, thyroxine, and testosterone were no rmal in NPY-knockout males fed ad libitum. A 48-hour fast resulted in a 50% reduction in leptin, a 60% reduction in thyroxine, a 75% reducti on in testosterone, and a 12-fold increase in corticosterone in both w ildtype and NPY-knockout mice. Fasting also increased the estrous cycl e length by 3 days in both wildtype and NPY-deficient female mice. We conclude that NPY is not essential for appropriate function of the gon adotropic, thyrotropic, or corticotropic axes under ad lib fed conditi ons or in response to acute fasting. (C) 1997 Elsevier Science B.V.