MINERALOCORTICOID AND GLYCYRRHIZIC ACID BLOCK STRESS-INDUCED HYPOTENSION IN RATS

1. The aim of this study was to investigate the effect of repeated exp osure to stress on tail blood pressure (TBP) of normal as well as GCA (glycyrrhizic acid) and steroid treated rats, Male Sprague-Dawley rats (250 g) were exposed to ether vapour to achieve light anaesthesia pri or to TBP recording. Rats were injected with either normal saline or n aloxone prior to exposure to stress. Tail blood pressure was recorded daily for 2 weeks. 2. We found that ether stress caused a transient dr op in TBP in control as well as in dexamethasone (DEX) treated rats. T he stress-induced fall in blood pressure was reduced by naloxone in co ntrol rats but not in DEX treated rats, However the transient drop in TBP following stress was not seen in either GCA or deoxycorticosterone (DOG) treated rats. 3. We conclude that first, the reduction in TBP w as due to the release of endogenous opioids caused by stress. Second, DOC may block the release of such endogenous opioids, preventing the d rop in TBP in response to stress, while DEX did not, Third, GCA caused a similar mineralocorticoid effect on reversing stress induced hypote nsion.