THE EFFECTS OF STRESS ON THE BLOOD CALCIUM LEVEL IN THE MALE WHITE RAT (Rattus norvegicus) by Howard Perry Cobb I I I was writ ten as part of the requirements for a Master of Science degree in Biology at the University of Richmond (May, 1985). The present experiment was designed to determine whether parathyroid hormone (PTH) can be considered a stress hormone. Parathyroidectomized (PX) male rats (160-200 g) were injected with 10, 20, or 30 USP units of PTH per 100 g body weight and subjected to confinement/UHF stress for a 1.5-h period. Serum calcium levels of these PX groups were compared to sham-operated rats stressed in the same manner. Serum calcium levels of the stressed uninjected PX rats and those injected with 10 USP PTH dropped by 7.7% and 14.7% respectively whereas serum calcium levels of the PX+20 USP PTH dropped only by 3.3%. Serum calcium levels of the PX+30 USP PTH showed an increase similar to the sham-operated rats (5.2% and 7.0% respectively). These findings clearly demonstrate a role for PTH in the stress response
