Carotid chemoreceptors participation in brain glucose regulation. Role of arginine-vasopressin.

Abstract

In previous studies we suggested that carotid body receptors (CBR) participate in glucose homeostasis (Alvarez-Buylla and Alvarez-Buylla, 1994). One of the most striking effects of the carotid chemoreceptor stimulation with cyanide (NaCN) is a rapid hyperglycemic reflex with glucose retention by the brain (Alvarez-Buylla et al., 1996). Pituitary and adrenals, two glands involved in glucose homeostasis, participate in the efferent pathway of this reflex (Alvarez-Buylla, 1997). Surgical removal of the neurohypophysis but not the anterior hypophysis abolishes the hyperglycemic reflex initiated in the CBR. Some of these efferent effects may be mediated through the direct action of neurohypophysial hormones on liver and adrenals. It has become progressively apparent that, in addition to its antidiuretic and vasopressor effects, vasopressin (AVP) also displays a powerful glycogenolytic action on the liver (Hems et al., 1978; Morel et al., 1992) and modulates glucose metabolism when the organism is under stress (Wideman and Murphy, 1993). Although AVP is widely distributed throughout the central nervous system (CNS) (Ostrowski et al., 1994), and it is known to act as an excitatory transmitter (Jakab et al., 1991), the effect of AVP on cerebral glucose homeostasis has not been documented. Importantly, carotid sinus perfusion with deoxygenated blood (Share and Levy, 1966) or following bilateral carotid occlusion (Harris, 1979), results in an increase in AVP levels in plasma. Carotid body receptor