Effect of stress and food restriction on blood pressure and lifespan of Dahl salt-sensitive rats.
OBJECTIVE
To evaluate the long-term consequences of stress in rats with genetic hypertension.


METHODS
Rapp-Dahl salt-sensitive rats, maintained on a low-salt diet, were stressed periodically over 8 weeks during which time their blood pressures were measured. In experiment 1 both stressed and unstressed control rats were given ad libitum access to food. Because of significant differences in body weights, in experiment 2 the unstressed controls were pair-fed to maintain their food intake at a level similar to that of the stressed rats.


METHODS
Rats were subjected to 2-h sessions of supine immobilization stress 5 days a week every other week for 8 weeks. Blood pressures were measured during non-stress weeks, at least 4 days after the last exposure to the stressor and at monthly intervals thereafter. Survival curves were also established.


RESULTS
In experiment 1 stressed rats developed hypertension at a slower rate than controls and lived significantly longer, but also weighted significantly less than controls, presumably because of diminished food intake. In experiment 2, in which food intake was controlled, body weights were similar in the two groups of rats, and hypertension developed at the same rate in both groups. Survival curves were not significantly different. Food restriction extended life compared with free feeding.


CONCLUSIONS
Stress need not have long-term, deleterious health consequences in rats with genetically inherited hypertension, whereas caloric restriction is protective.
Natelson
B H
BH
Neurobehavioral Unit, VA Medical Center, East Orange, New Jersey 07018-1095.
Ottenweller
J E
JE
Servatius
R J
RJ
Drastal
S
S
Bergen
M T
MT
Tapp
W N
WN
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001835:Body Weight; D002149:Energy Intake / Q000502:physiology*; D006973:Hypertension / Q000209:etiology* / Q000401:mortality; D008136:Longevity / Q000502:physiology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains / Q000502:physiology*; D013312:Stress, Physiological / Q000150:complications / Q000503:physiopathology*; D016019:Survival Analysis