Sympathetic function and development of temperature regulation

¹ Department of Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York

Experiments were performed to determine the role of the sympathetic nervous system in the maturation of temperature regulation in the preweanling rat. Animals 6–16 days of age were placed in a 15 C air environment. The time required for their colonic temperatures to drop from 30 to 20 C was taken as an index of cooling rate. Reserpine, pentolinium, and nerve-growth-factor antiserum were used to evaluate autonomic function. None of these blocking agents influenced the rate of cooling of the 6-day-old animal. In the 16-day-old animal the same agents had a pronounced effect, such that control animals did not cool, while animals that had received reserpine cooled at a rate of 0.18 C/min, animals that had received the pentolinium cooled at a rate of 0.07 C/min, and animals that had received the antiserum for the first 5 days of life cooled at a rate of 0.15 C/min. This study indicates that the sympathetic nervous system is concerned with the development of homeothermy in the rat.

Key Words: physiology of the newborn • preweanling rat • developmental physiology

Submitted on August 2, 1963