Attenuation of the afferent limb of the baroreceptor reflex in streptozotocin-induced diabetic rats

• Published in: Autonomic neuroscience Vol. 89; no. 1; pp. 86 - 95
• Main Authors: Gouty, Shawn, Regalia, Jen, Helke, Cinda J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 20.06.2001; Elsevier
• Subjects: Animals; Associated diseases and complications; Baroreceptor afferents; Biological and medical sciences; Blood Pressure; c-Fos; Diabetes Mellitus, Experimental - physiopathology; Diabetes. Impaired glucose tolerance; Diabetic Neuropathies - physiopathology; Diabetic rats; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Heart Rate; Male; Medical sciences; Neurons, Afferent - chemistry; Neurons, Afferent - physiology; Phenylephrine - pharmacology; Phenylephrine-induced reflexes; Pressoreceptors - drug effects; Pressoreceptors - physiology; Proto-Oncogene Proteins c-fos - analysis; Rats; Rats, Sprague-Dawley; Solitary Nucleus - cytology; Solitary Nucleus - physiology; streptozotocin; Sympathomimetics - pharmacology; c-Fos; Diabetic rats; Baroreceptor afferents; streptozotocin; Phenylephrine-induced reflexes; Endocrinopathy; Nervous system diseases; Rat; Diabetes mellitus; Rodentia; Central nervous system; Peripheral neuropathy; Solitary nucleus; Experimental disease; Vertebrata; Mammalia; Animal; Baroreflex; Complication; Baroreceptor; Brain (vertebrata)
• DOI: 10.1016/S1566-0702(01)00256-9
• ISSN: 1566-0702

Diabetic autonomic neuropathy is a common complication following prolonged diabetes. Alterations of cardiovascular reflexes contribute to the increased cardiovascular morbidity and mortality seen in diabetic patients. This study sought to better characterize these complications by investigating the afferent limb of the baroreceptor reflex in an experimental rat model of diabetes. Streptozotocin (STZ)-induced diabetic and euglycemic control rats were studied at 8- and 16-week time points after initiation of the experiment. Activation of the afferent limb of the baroreceptor reflex was assessed by measuring the numbers of c-Fos-immunoreactive (ir) neurons in the CNS site of termination of the baroreceptor afferent neurons, the nucleus of the solitary tract (NTS). Initial experiments established that baseline cardiovascular parameters and NTS expression of c-Fos-ir neurons were not different between diabetic and control rats at either time point. Phenylephrine (PE)-induced activation of baroreceptors resulted in a significant elevation in the numbers of c-Fos-ir neurons in the NTS of control rats. Although diabetic rats showed similar pressor responses to PE, the activation of c-Fos-ir neurons in the NTS of diabetic rats was significantly attenuated. At both 8 and 16 weeks, STZ-induced diabetic rats had significantly fewer c-Fos-ir neurons in the commissural NTS and in the caudal subpostremal NTS when compared to the non-diabetic control animals receiving PE. These data suggest that STZ-induced diabetes, for a period of 8 and 16 weeks, results in reduced activity in the afferent baroreceptor input to the NTS, and are consistent with diabetes-induced damage to baroreceptor afferent nerves.