Distribution of fibroblast growth factor-5 in rat hypothalamus, and its possible role as a regulator of feeding behaviour.
We previously reported that a transcript of fibroblast growth factor-5 (FGF-5) was more abundant in the brain of postnatal and adult mice than in the embryonic brain. This suggested that FGF-5 plays some role in the mature brain. Here, we have investigated the spatiotemporal expression and function of FGF-5 in the adult rat hypothalamus with the emphasis on feeding behaviour. In situ hybridization experiments demonstrated that, in both adequately fed and fasted (20 h) rats, FGF-5 transcripts were present within several nuclei in the hypothalamus (viz. the magnocellular part of the paraventricular nucleus, supraoptic nucleus, arcuate nucleus, median eminence, and ventromedial hypothalamic nucleus), but not in the lateral hypothalamic area. Quantitative detection of FGF-5 mRNA in the hypothalamus (especially in the paraventricular nucleus) indicated that food deprivation (20 h) reduced the expression of this gene to almost one-half of that seen in the control (fed) rats. The expression recovered to the control level after 1 h re-feeding, and this recovery persisted for several hours. Furthermore, FGF-5, when infused into the third ventricle, consistently reduced food intake, water intake and body weight gain, all in a dose-dependent manner. These results suggest that FGF-5 in the hypothalamus acts as a physiological regulator of feeding behaviour, and that its decreased expression during food deprivation may be important in stimulating appetite.
Li
A J
AJ
Biosignaling Department, National Institute of Bioscience and Human- Technology, Tsukuba, Ibaraki, Japan.
Ozawa
K
K
Tsuboyama
H
H
Imamura
T
T
D000818:Animals; D002552:Cerebral Ventricles; D002940:Circadian Rhythm / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D051521:Fibroblast Growth Factor 5; D005346:Fibroblast Growth Factors / Q000032:analysis* / Q000235:genetics; D007031:Hypothalamus / Q000737:chemistry*; D007263:Infusions, Parenteral; D008297:Male; D009479:Neuropeptides / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
C496451:Fgf5 protein, rat; D009479:Neuropeptides; D012333:RNA, Messenger; D051521:Fibroblast Growth Factor 5; D005346:Fibroblast Growth Factors