Submitted on September 17, 2003
Accepted on April 28, 2004
The Effect of icv Angiotensin II on Body Weight and Food Intake in Adult Rats
James P Porter1* and Kristen R Potratz1
1 Physiology and Developmental Biology and the Neuroscience Center, Brigham Young University, Provo, UT, USA
* To whom correspondence should be addressed. E-mail: james_porter{at}byu.edu.
We recently reported that icv infusions of angiotensin II (ANG II) decreased food intake and increased energy expenditure in young rats. The aim of the present study was
to determine if icv ANG II has similar effects in adult rats. The time-course of the effect was also investigated with the idea that at earlier time-points a potential role for increased hypothalamic expression of corticotropin releasing hormone (CRH) in the anorexia could be established. Finally, the contribution of ANG II-induced water drinking to the decrease in food intake was directly investigated. Rats received icv saline or ANG II using osmotic minipumps. Food intake, water intake, and body weight were measured daily. Experiments were terminated 2 days, 5 days, or 11 days after the beginning of the
infusions. ANG II (~ 32 ng/kg/min) produced a transient decrease in food intake that lasted for 4-5 days although body weight continued to be decreased for the entire
experiment most likely due to increased energy expenditure as evidenced by increased uncoupling protein-1 mRNA expression in brown adipose tissue. At 11 days and 5 days,
the expression of CRH mRNA was decreased. At 2 days, CRH expression was not suppressed even though body weight was decreased. The decrease in food intake and body weight were identical whether or not rats were allowed to increase water
consumption. These data suggest that in adult rats ANG II acts within the brain to affect food intake and energy expenditure in a manner that is not related to water intake.
