HRH1 and Hyperglycemia: Although HA is highly increased at E14 under hyperglycemia, the increased expression of H1R at E12 may be responsible for the increased neuron differentiation at E14, because the neurogenic effect of HA depends on the activation of this receptor (Molina-Hernandez and Velasco, 2008; Molina-Hernandez et al., 2013).