Abstract
Abstract Fibroblast growth factors (FGFs) play important roles in embryonic development and in adult life by controlling cell proliferation, differentiation and migration. FGF1 is one member of the FGF family, which promotes cell growth, proliferation and neurogenesis. To study the effect of endogenous FGF1 in the mouse brain, we produced FGF1 antibodies, named FGF1#14, FGF1#15 and FGF1#16, that are raised in the rabbits against specific mouse FGF1 polypeptides. We showed that FGF1#14, FGF1#15 and FGF1#16A recognized recombinant mouse FGF1 protein using Western blotting analysis. These antibodies could also recognize endogenous FGF1 in the mouse brain using immunohistochemistry-paraffin (IHC-P) analysis. Particularly, FGF1#16A could be used to apply to Western blot, IHC-P and immunohistochemistry (IHC). In addition, immunoabsorption assay results indicated that FGF1#16 were specific to detect FGF1. Among these results, we found that FGF1#16A immunoreactive cells were present in the paraventricular nucleus (PVN) of the hypothalamus, which is an important brain region in regulating energy homeostasis. Interestingly, we also found FGF1#16A immunoreactive cells could express both oxytocin and nesfatin-1. Both proteins are anorexigenic markers in several studies. We prepared mice that were maintained under regular diet, fasted, refed or high-fat diet (HFD) for double labeling with FGF1#16A/oxytocin or FGF1#16A/nesfatin-1 to determine the effect of FGF1 in diet regulation. Our results showed that FGF1#16A immunoreactive cells were higher in fasted mice at bregma -0.22 mm and -0.46 mm and in HFD mice at bregma -0.46 mm. Previous studies have indicated that FGF1 regulates feeding behavior through intracerebroventricular injection. It has also been reported that FGF1 is highly induced in adipose tissue in response to HFD. In conclusion, our results revealed that FGF1 is increased in the fasted mice and in HFD mice at specific bregma regions by counting immunoreactive cells. Thus, our results are consistent with the notion that FGF1 may have an effect in diet regulation. Key words: FGF1, PVN, oxytocin, nesfatin-1 and diet regulation