GNRH1 and hypogonadotropic hypogonadism: Another experimental evidence, which plays in favor of the hypothesis that glia regulate GnRH neurons is the fact that selective depletion of the glial fibrillary acidic protein produced by tanycytes in transgenic mice caused a marked decrease in the testosterone levels and testicular weight, hypogonadotropic hypogonadism condition and a sharp decrease in the number of GnRH neurons [16].