AJP - Endocrinology and Metabolism, Vol 243, Issue 5 398-E406, Copyright © 1982 by American Physiological Society
Effect of phenoxybenzamine on development of adipose tissue in lean and obese Zucker rats
K. Comai and A. C. Sullivan
Young male Zucker lean (Fa/-) and obese (fa/fa) rats were fed the
alpha-adrenergic blocking agent phenoxybenzamine as a dietary admixture for
35 days. In lean and obese rats, phenoxybenzamine treatment decreased
significantly body weight gain, food consumption, grams of carcass fat, and
grams of carcass protein. Lean rats exhibited reduced fat cell size and
number in retroperitoneal, epididymal, and inguinal fat depots. Obese rats
treated with phenoxybenzamine exhibited significantly decreased numbers of
fat cells in the retroperitoneal, epididymal, and inguinal fat depots and a
small decreased cell size in the inguinal fat depot only. The levels of
carcass fat and protein and fat cell number in obese and lean rats treated
with phenoxybenzamine for 35 days were similar to pretreatment values in
agreement with the lack of body weight gain. Although values in agreement
with the lack of body weight gain. Although rats exhibited marked decreases
in fat accumulation during phenoxybenzamine treatment, fat cell size and
number returned to control values during the posttreatment period with a
marked hyperplasia occurring particularly in the retroperitoneal fat depot
of obese rats. Serum levels of insulin were suppressed and free fatty acid
levels increased in obese rats during phenoxybenzamine treatment,
suggesting a stimulation of the sympathoadrenal system. This study shows
that despite severe restrictions in fat cell proliferation during the
rapid-growth phase of the obese Zucker rat, the mechanisms for cellular
proliferation and fat deposition remain intact.
