STRESS RESPONSE IN RAT FROM HARNESSING FOR CHRONIC INTRAVENOUS-INFUSION

The back harness attached to the rat in these experiments clearly produced a continually stressed animal, reflected by a profound weight loss during the first 24 h and by a reduced growth rate in the presence of normal food intake. The stress was only alleviated by removing the harness from the animal. Extreme weight loss during the 1st day of harnessing associated with orally fed rats could be prevented by i.v. infusion of a complete nutritional diet. Comparison of the nonharnessed and harnessed rats'' behavior during the period when body weight was obtained suggests that the harnessed rats were hyperactive and psychologically disturbed. Hyperactivity and stressed state were apparently major contributors to the reduced growth rate. A further reflection of continual stress was from the abnormally small livers of the experimental animals when compared to nonharnessed controls. This may be of extreme importance in view of the liver''s central role in regulating systemic body metabolism.