AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 6 1533-R1538, Copyright © 1995 by American Physiological Society
Changes in eating behavior and thermogenic activity following inhibition of nitric oxide formation
B. De Luca, M. Monda and A. Sullo
Department of Human Physiology and Integrated Biological Function, Filippo Bottazzi Second University of Naples, Italy.
The effects of the inhibition of nitric oxide (NO) production on eating
behavior and thermogenesis were evaluated in the present experiments.
NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO production,
was injected intraperitoneally or intracerebroventricularly, and food
intake, oxygen consumption rate, and interscapular brown adipose tissue
(BAT) temperature were evaluated in conscious rats. The firing rate of
sympathetic nerves innervating interscapular BAT was recorded in
urethan-anesthetized animals. L-NAME, intraperitoneally injected, decreased
food intake, oxygen consumption, temperature, and firing rate of
sympathetic nerves innervating interscapular BAT. Intracerebroventricular
injection of L-NAME decreased food intake and enhanced oxygen consumption,
temperature, and firing rate of sympathetic nerves innervating BAT. The
latter changes were similar to those found after lateral hypothalamic
lesions. The opposite changes in oxygen consumption, temperature, and
sympathetic activity of BAT that followed L-NAME injection through the two
different routes were probably due to different effects of the molecule on
sympathetic output. Impaired brain production of NO, which followed
intracerebroventricular L-NAME, directly increased sympathetic activity,
whereas the same activity that followed intraperitoneal L-NAME was
depressed by increased blood pressure, which was elicited by the impaired
peripheral production of NO.
