Fluoxetine alters feeding behavior and leptin levels in chronically-stressed rats.

Stress-induced alterations in feeding behavior are sexually dimorphic and have been related to changes in monoamine levels. Fluoxetine is commonly used as an antidepressant and has also been suggested as an adjunct to other strategies to treat obese individuals. Leptin may interact with stress hormones and with the brain serotonergic system, possibly affecting the feeding behavior of stressed rats. The aim of this study is to evaluate the interaction between chronic fluoxetine treatment and leptin levels in adult female Wistar rats submitted to chronic variable stress. After 30 days of stress, control and stressed groups were subdivided into two groups that received daily injections of vehicle or fluoxetine (8 mg/kg, i.p.). Body weight was evaluated before and after fluoxetine treatment. The animals gained weight with time, signifying that there is a difference in weight gain over time when fluoxetine-treated animals are, or not, subjected to the stress model. Both fluoxetine and stress induced a decrease in sweet food consumption. On the 60th day of fluoxetine treatment, leptin levels were decreased in fluoxetine-treated animals and there was no effect of stress. We conclude that chronic fluoxetine treatment induced a decreased intake of sweet food, as well as a reduction in leptin levels, and that this result could represent a compensatory response to reduced food intake rather than a direct anorectic mechanism. No interaction with chronic stress was observed.

Interaction between estradiol replacement and chronic stress on feeding behavior and on serum leptin.

Exposure to stress may cause either an increase or a decrease in food intake. Behavioral and physiological responses to stress, including alterations in feeding behavior, are sexually dimorphic. This study aimed to evaluate the interaction between estradiol levels and chronic variate stress on the intake of sweet food and on serum levels of leptin, a hormone secreted by the adipose cells with a role in the regulation of body weight. Adult female Wistar rats were used. After ovariectomy, the animals received estradiol replacement (or oil) subcutaneously. Rats were then divided in controls and stressed (submitted to 30 days of variate stress). Consumption of sweet food and of serum leptin was measured. Although animals receiving estradiol replacement presented smaller weight gain, they showed an increased consumption of sweet food. Chronic variate stress decreased sweet food intake at 30, but not at 20, days of treatment. Estradiol replacement in the stressed group prevented both the reduction observed in sweet food intake and the increase in leptin levels. These results suggest that there is an interaction between chronic stress and estradiol replacement in feeding behavior concerning sweet food consumption, and this interaction may be related to altered leptin levels.