Intracerebroventricular administration of leptin increases anxiety-like behavior in female rats after semi-starvation--implications for anxiety in eating disorders

• Published in: Osaka City medical journal Vol. 55; no. 1; p. 9
• Main Authors: Yamauchi, Tsuneo, Inoue, Koki, Iwasaki, Shinichi, Muramatsu, Tomohiro, Hayashi, Teruaki, Kiriike, Nosuo
• Format: Journal Article
• Language: English
• Published: Japan 01.06.2009
• Subjects: Animals; Anorexia Nervosa - psychology; Anxiety - etiology; Corticotropin-Releasing Hormone - physiology; Estrus; Feeding and Eating Disorders - psychology; Female; Injections, Intraventricular; Leptin - administration & dosage; Leptin - blood; Leptin - physiology; Maze Learning; Rats; Rats, Wistar; Starvation - psychology
• ISSN: 0030-6096

Patients with eating disorders often exhibit abnormal eating conditions like food restriction, adipocyte and body weight reduction, and pathologic anxiety-like behavior. The role of leptin, which is recognized as an adipocyte-derived hormone, on anxiety-like behavior in eating disorders is still unclear. We investigated the role of leptin on anxiety-like behavior with or without semi-starvation using the elevated plus-maze test in adolescent female rats. In our first experiment, anxiety-like behavior was evaluated with the elevated plus-maze test 30 min after intracerebroventricular administration of 3 microg of leptin or vehicle. In our second experiment, the rats were allowed access to food for only 2 hr each day for 7 days. Then, leptin or vehicle was administered to the rats after the last 2 hr feeding period, and anxiety-like behaviors were evaluated in the same way as in the first experiment. In the first experiment, there was no difference between the anxiety-like behaviors observed after leptin administration and those seen after vehicle administration. Under the conditions of semi-starvation, however, the percentage of time spent in the open arms in the rats given leptin was lower than that in rats given vehicle. These results suggest that leptin administration causes anxiety-like behavior only after semistarvation. Leptin might play an important role in pathologic anxiety-like behavior in eating disorders.