BEHAVIOR OF THE TRANSGENIC (MREN2) 27 RAT

The first model of genetically engineered hypertension, the transgenic rat TGR (mREN2)27, provides a unique opportunity to study the behavio ural effects of an altered brain renin-angiotensin system. The TGR (mR EN2)27 rats, characterised by fulminant hypertension, show differences in both the peripheral and central angiotensin systems. The behaviour of male transgenic TGR (mREN2)27 and male Sprague-Dawley rats were de termined by 4 behavioural tests. While on the elevated X-maze the TGR (mREN2)27 rat showed a greater 'anxiogenic' profile (fewer open arm en tries) than the control Sprague-Dawley rats, this 'anxiogenic' profile increased further during a second exposure to the elevated X-maze 24 h later. in comparison the behaviour of the male Sprague-Dawley rats w as not different between the two exposures to the elevated X-maze. Loc omotor activity did not differ between either the TGR (mREN2)27 or Spr ague-Dawley rats when placed in a 1 m(2) open-field for 10 min. A shor t period of fluid-deprivation (3 h) reversed the 'anxiogenic' profile of the TGR (mREN2)27 on the elevated X-maze. Administration of captopr il (20 mg . kg(-1) body weight) in the drinking water of the TGR (mREN 2)27 rats and Sprague-Dawley rats reversed the anxiogenic profile of t he TGR (mREN2)27 rat on the elevated X-maze but did not alter the beha viour of the Sprague:Dawley rats.