AQP9 and nutritional deficiency disease: Arrighi et al. (2010) also observed a reduction in AQP9 expression in the epididymis of adult rats subjected to malnutrition during the perinatal period. AQP9 expression is modulated by testosterone, and the proximal regions of epididymis are more sensitive to testosterone variations. These features could also explain the lower AQP9 expression in the epididymal proximal regions of LP rats since it is related to the decrease in serum testosterone in LP animals at this age (Cavariani et al., 2019).