Efferent metabolic effects of area postrema stimulation in renal hypertensive rats

Electrical microstimulation of area postrema in anesthetized normotensive (NR) and renal hypertensive (RHR) rats produced increases of about 53% in rates of glucose metabolism in nucleus tractus solitarii and dorsal motor nucleus of the vagus nerves. However, in nucleus ambiguus, ventrolateral medullary C1 region, locus coeruleus, and lateral parabrachial nucleus, all of which are monosynaptically innervated by area postrema neurons, metabolic responsiveness to postremal stimulation was considerably attenuated in RHR (average increase of 16%) compared to the same structures in NR (average increase of 36%). Disturbances of brainstem neurotransmission or tissue reactivity to postremal pathway activation thus appear to be part of the central pathophysiology of chronic renal hypertension.