Central nuclei mediating estrogen-induced changes in autonomic tone and baroreceptor reflex in male rats

• Published in: Brain research 2003-01, Vol.961 (2), p.190-200
• Main Authors: Saleh, Tarek M., Connell, Barry J.
• Format: Article
• Language: English
• Subjects: Amygdala - drug effects; Amygdala - physiology; Animals; Autonomic Nervous System - physiology; Baroreflex - drug effects; Baroreflex - physiology; Biological and medical sciences; Blood Pressure - drug effects; Blood Pressure - physiology; Central nucleus of the amygdala; Efferent Pathways - physiology; Estrogens - administration & dosage; Estrogens - physiology; Fundamental and applied biological sciences. Psychology; Heart Rate - drug effects; Heart Rate - physiology; Hypothalamic Area, Lateral - drug effects; Hypothalamic Area, Lateral - physiology; Insular cortex; Lateral hypothalamic area; Lidocaine - pharmacology; Male; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Parabrachial nucleus; Rats; Rats, Sprague-Dawley; Sodium Channel Blockers - pharmacology; Sympathetic Nervous System - physiology; Synaptic Transmission - drug effects; Thalamic Nuclei - drug effects; Thalamic Nuclei - physiology; Time Factors; Vagus Nerve - physiology; Ventral posteromedial thalamus; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(02)03928-8

The current investigation examines the significance of estrogen in central cardiovascular regulatory nuclei in modulating autonomic tone and baroreceptor reflex function. Experiments were done in anaesthetized male Sprague-Dawley rats. Changes in autonomic tone were assessed by monitoring vagal and renal efferent nerve activities before and following bilateral injection of estrogen into select central autonomic nuclei. In the first study, selective blockade of neurotransmission through the central nucleus of the amygdala (CNA), lateral hypothalamic area (LHA) and ventral posteromedial thalamic nucleus (VPM) using the local anaesthetic lidocaine was done to determine which nuclei were involved in mediating the autonomic changes observed following bilateral injections of estrogen into the insular cortex (IC). In the second study, the role of the parabrachial nucleus (PBN) in mediating the autonomic changes observed following bilateral estrogen injections into the CNA, LHA, VPM and IC was determined by blocking neurotransmission through the PBN using lidocaine. Injections of estrogen into the IC produced a significant increase in renal sympathetic nerve activity (RSNA; from 10±2 to 24±4 μV/sec; p