IMMOBILIZATION STRESS INDUCES VASODEPRESSOR AND ALTERED NEUROENDOCRINE RESPONSES IN THE ADULT STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE MALE-RAT

The effects of acute (1 h) and daily repeated immobilization stress (1 4 days, twice-daily, 1 h) were studied on arterial blood pressure and heart rate and on the blood levels of several hormones in the adult (5 months old) stroke-prone spontaneously hypertensive rat (SHRSP) and i n the age-matched normotensive Wistar-Kyoto (WKY) rat. The major resul t was the development of a long-lasting vasodepressor response in the SHRSP, while the same acute or repeated immobilization stress in the W KY rat led to the development of a prolonged vasopressor response. Dif ferential changes to stress were also observed in practically all neur oendocrine axes with the exception of the pituitary-adrenal axis. The vasodepressor response to immobilization stress in SHRSP may be relate d to an exaggerated defence-like reaction causing an enhanced vasodila tion in the skeletal muscle beds associated with a tachycardia similar to that in the normotensive control rats.