A Role for the Fibroblast Growth Factor Family in Depression and Circadian Rhythms

In this set of experiments, we examined a number of variables that are crucial to determining the effects of fibroblast growth factor-9 (FGF9) on affective behavior. Animals were injected on post-natal day two (PND2) to determine whether a single early-life subcutaneous (s.c.) injection had long-lasting effects on adult behavior as was observed with FGF2. We observed no significant changes in a battery of adult behaviors. We also tested whether an intraperitoneal (i.p.) injection of FGF9 had an effect on anxiety-like or depression-like behavior. We found no effect on anxiety-like or depression-like behavior following an acute injection via this route of administration. By contrast, we observed that an acute intracerebroventricular (i.c.v.) microinjection of FGF9 increased depression-like behavior during the first half of the light-cycle. The depressionogenic effect was sensitive to time manipulations. Testing during the second-half of the light-cycle revealed an overall decrease in escape activity that may mask the decrease in escape activity observed in the first-half of the light-cycle. We further showed that the increase in depression-like behavior after an acute microinjection of