GRIA1 and Hyperammonemia: For example, ammonia would prevent activation of NMDA receptors in rat cerebellar neuronal cultures [44], chronic hyperammonemia would impair the extracellular glutamate and glutamate-nitric oxide-cyclic GMP pathway in cerebellar neurons in culture and in the rat in vivo [45, 47], hyperammonemia alters membrane expression of GluA1 and GluA2 subunits of AMPA receptors in hippocampus with altered spatial memory in rats [48].