The mouse FGF family comprises 22 members and could be divided into seven subfamilies: FGF1 (FGF1 and FGF2), FGF4 (FGF4-6), FGF7 (FGF3, FGF7, FGF10, and FGF22) FGF8 (FGF8, FGF17, and FGF18), FGF9 (FGF9, FGF16, and FGF20), FGF11
(FGF11-14), and FGF15 subfamilies (FGF15, FGF21, and FGF23) [39, 40].
However, they differed in that the effects on fgf2 and fgfr4 were significantly larger for diazinon, and the two agents also showed dissimilar, smaller effects on fgf11, fgf14, and fgfr1.
For the genes encoding FGFs, chlorpyrifos exposure produced a significant overall decrement (main treatment effect, p < 0.05) and specific reductions in the expression of fgf2, fgf11, fgf20, and fgf22 (Figure 1).
The lower dose of diazinon caused a large reduction in forebrain fgf20 expression as did chlorpyrifos, but diazinon failed to decrease forebrain fgf2 or fgf11 significantly, and instead evoked a reduction in fgf14 (Figure 2A).
There were also smaller effects on fgf11, fgf14, fgf22, fgfr1, and fgfr4, each of which also displayed either a regionally selective effect or a difference between the two organophosphates.
It is also noteworthy that we saw several important differences in the effects of chlorpyrifos as compared with diazinon: chlorpyrifos decreased fgf2 and fgf11 in the forebrain, whereas diazinon did not; in the brain stem, diazinon reduced fgf2 and induced fgfr4 much more than did chlorpyrifos, and also had effects on forebrain fgf14 and fgfr1 that were not seen with chlorpyrifos.