title: Cardiovascular and single-unit responses to L-glutamate injection into the posterior insular cortex in rat.
abstract: The insular cortex in rat is a longitudinal strip that runs along the rostral half of the rhinal fissure. The previous studies showed connections between the posterior insular cortex (PIC) and some major cardiovascular centers. Based on the stimulation site, electrical or chemical stimulation of the PIC induced an increase or a decrease in blood pressure (BP) and heart rate (HR). There is no report of simultaneous cardiovascular and single-unit recording microinjection of Glut in the PIC. In this study, L-glutamate was microinjected into the PIC of urethane anesthetized rats and arterial pressure, HR and single-unit responses were recorded simultaneously. Also the response of the neurons to baroreceptor activation was explored. Glut produced five types of long oscillatory, pressor, depressor, bradycardic and tachycardic cardiovascular responses, with no association between pressure and HR responses. We also observed five single-unit responses, consisting of short excitatory, long oscillatory, excitatory, inhibitory and mixed responses. There was an association between oscillation in BP and in single-unit response. There were some differences between the two sides especially for single-unit responses. In conclusion, there were five types of cardiovascular and five types of single-unit responses, to Glut microinjection into PIC, from which three types were correlated. The left side of the PIC is involved more in the cardiovascular functions. These data along with the fact that most recorded neurons responded to baroreceptor activation, might imply the presence of feedback systems in the PIC, producing irregularity in BP and HR.
authors: Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors: A
authors: A
authors: Ranjbar
authors: Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. Electronic address: mahatm@sums.ac.ir.
authors: M
authors: M
authors: Hatam
authors: Deptartment of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: A
authors: A
authors: Nasimi
mesh_terms: D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects*; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D008959:Models, Neurological; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018698:Glutamic Acid
keywords: blood pressure; glutamate; heart rate; posterior insular cortex; single-unit recording