Issue Archive

[Facilitative effect of glycine on regulation of baroreflex in the hypothalamic paraventricular nucleus of conscious rats.] [Ariticle in Chinese]

YIN Gui-Dong, BING Yan-Hua, GAO Xiao-Lei, Jin Yuan-Zhe, JIN Qing-Hua^*

Department of Physiology and Pathophysiology, Yanbian University Medical College, Yanji 133000, China

Abstract

The hypothalamic paraventricular nucleus (PVN) is a central site for integration of the endocrine system and the autonomic nervous system. Despite a number of studies have pointed out the importance of the PVN in the central regulation of cardiovascular functions, the chemical mediators in the PVN responsible for mediating baroreflex are not well understood. In the present study, we used the conscious rats to investigate the possible involvement of glycine (Gly) in PVN in the central regulation of baroreflex induced by intravenous injection of phenylephrine (0.8 μg/0.04 mL, in 3 min). Then, the microdialysis sampling was performed in the PVN and the concentration of Gly in the microdialysate was measured by high performance liquid chromatography (HPLC) combined with electrochemical techniques, and mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously. Injection of phenylephrine elicited a significant increase (P<0.01) in MAP from the baseline of (99.5±14.2) mmHg to the maximum of (149.8±19.5) mmHg and a decrease (P<0.01) in HR from the baseline of (400.8±33.1) beats/min to the minimum of (273.4±40.8) beats/min, respectively. Synchronously, the injection of phenylephrine increased the level of Gly in the microdialysate from the PVN to (162.9±27.3)% of the basal level (P<0.05). Perfusion of strychnine (100 μmol/L), an antagonist of Gly receptor, into the PVN enhanced the pressor response and attenuated the bradycardic response during the baroreflex, resulting in a decrease in baroreflex sensitivity (P<0.001). Whereas, the perfusion of Gly (1 mmol/L) into the PVN did not affect the pressor response but enhanced the bradycardic response during the baroreflex, resulting in an increase in baroreflex sensitivity (P<0.001). These results suggest that endogenous Gly in the PVN may act via strychnine-sensitive Gly receptor to produce a facilitative effect on baroreflex.

Key words: Hypothalamic paraventricular nucleus; baroreflex; glycine; strychnine

Received: 2008-06-23　　Accepted: 2009-03-04

Corresponding author: 金清华　　E-mail: yqinghua@ybu.edu.cn

Citing This Article：

YIN Gui-Dong, BING Yan-Hua, GAO Xiao-Lei, Jin Yuan-Zhe, JIN Qing-Hua. [Facilitative effect of glycine on regulation of baroreflex in the hypothalamic paraventricular nucleus of conscious rats.] [Ariticle in Chinese]. Acta Physiol Sin 2009; 61 (2): 155-160 (in Chinese with English abstract).