Abstract
Neuropeptide W(NPW) is a novel hypothalamic peptide that activates the orphan G protein-coupled receptors, GPR7 and GPR8. We have recently demonstrated that intracerebroventricular (i.c.v.) administration of NPW30 increases the blood pressure, heart rate, and plasma norepinephrine and epinephrine concentrations in conscious rats. This observation indicates that central NPW regulates sympathetic nervous outflow and affects cardiovascular function. NPW was recently reported to be an important stress mediator in the central nervous system that modulates the hypothalamus-pituitary axis. To examine the effects of NPW on the neural activity of the hypothalamic paraventricular nucleus (PVN), which is an integrative center of the autonomic and endocrine functions, we simultaneously recorded the single unit in the PVN neurons, arterial blood pressure, and heart rate in conscious freely-moving rats. Single unit activities were examined for their spontaneous firing patterns and responses to stressors, including disturbance in arterial blood pressure and systemic administration of cholecystokinin-8 (CCK). Non-phasic-type neurons showed excitation to i.c.v. administration of NPW; furthermore, these neurons showed sensitivity to CCK, but did not respond to phenylephrine(PE) and nitroprusside(SNP). Our data suggest that central NPW, at least in part, activates PVN neurons, which are affected by CCK, probably via the vagus nerves, independently of blood pressure changes. [J Physiol Sci. 2006;56 Suppl:S205]
