NPY Y1 receptors exert opposite effects on corticotropin releasing factor and noradrenaline overflow from the rat hypothalamus in vitro.

Neuropeptide Y (NPY), corticotropin releasing factor (CRF) and noradrenaline play important roles in the regulation of a number of endocrine and autonomic functions. NPY is co-localised with noradrenaline in the central nervous system and has been observed to modulate noradrenaline release. Recent morphological and physiological studies also support co-modulatory interactions between NPY and CRF. Earlier in vivo studies in our laboratory showed a potentiation of K(+)-stimulated noradrenaline release following NPY administration, possibly due to an NPY Y1 receptor mechanism. In this study, in vitro superfusion techniques were established to simultaneously monitor the release of endogenous noradrenaline and CRF from the hypothalamus of adult rats and to examine the direct neuromodulatory action of NPY on the overflow of CRF and noradrenaline. Administration of 0.10 microM NPY significantly increased CRF overflow to 395% basal levels and reduced hypothalamic noradrenaline overflow to 61% of basal levels. These effects were blocked by prior administration of the NPY Y1 receptor antagonist GR231118. Thus, this study suggests that NPY, working through a Y1 receptor, has dual and opposing effects on CRF and noradrenaline overflow in vitro.