Brain stem response to phasic gastric distension

Abstract

To explore the physiological characteristics of central projections of gastric afferent fibers, single-unit activity was recorded extracellularly from neurons in the brain stem during phasic distension of the stomach in cats anesthetized by halothane and nitrous oxide. The brain stem units were identified on the basis of discharge patterns that were phase locked to distension or relaxation of the stomach. Based on stereotaxic coordinates, the units responding to the distension stimulus were located in the region of nucleus and tractus solitarius and extended ventrally toward nucleus ambiguus. Both phasically and tonically discharging units were identified, which exhibited either an excitatory or inhibitory response during distension of the stomach at pressures of 6-8 cmH2O. Units excited by distension increased their firing rate or began to discharge near the peak of distension at rates of 4-6 Hz. Other units responded only during the phase when the distending pressure was decreasing. Sectioning the vagi abolished the response of these brain stem units to gastric distension. The origin of the stimulus that initiated the unit response was localized in the fundus and body of the stomach in many instances. The results indicate that neuronal activity in discrete areas of the brain stem of the cat is altered in response to phasic gastric distension and that this response is vagally mediated.

Cholecystokinin Release by Gastric Distension – An Atropine-Sensitive Mechanism

“…31). It has been proposed that target organs are thereby influenced via long vagal efferent fibers [30].…”

Effects of intraduodenal fatty acids on appetite, antropyloroduodenal motility, and plasma CCK and GLP-1 in humans vary with their chain length

“…Plasma was separated by centrifugation (3,200 rpm, 15 min, 4°C) within 30 min of collection and stored at Ϫ70°C until assayed.…”

Electrophysiological Responses of Nucleus Tractus Solitarius Neurons to CCK and Gastric Distension in Newborn Lambs

“…Dorso-medial medullary neurons excited or inhibited by gastric distension have been previously identified in the adult rat (Ewart and Wingate, 1983;García-Díaz et al, 1988), the adult cat (Barber and Burks, 1983;Barber and Yuan, 1989) and the adult sheep Leek, 1972, 1973). However, Only Raybould et al (1985Raybould et al ( , 1988) went further in their description and demonstrated that gastric distension and circulating CCK-8S produced the same effect on brainstem neurons.…”

“…As such the NTS forms an important relay center for the transmission of visceral information to other brain structures (Jean, 1991). Electrophysiological studies in the rat have shown that some neurons within the nucleus respond to gastric distension (Barber and Burks, 1983;García-Díaz et al, 1988;Raybould et al, 1985;Raybould et al, 1988), peripherally administered gastrointestinal peptides (Barber and Burks, 1987;Raybould et al, 1985Raybould et al, , 1988Yoshida-Yoneda et al, 1996) or gastric vagal stimulation (Barber and Yuan, 1989;Barber et al, 1990). It appears from these studies that circulating CCK and gastric distension produce similar effects on brainstem neurons and that this effect is mediated by a common pathway, the vagus, as vagotomy abolishes all responses (Raybould et al, 1988).…”