SLC9A3 and familial glucocorticoid deficiency: Administration of glucocorticoids to neonatal rabbits increases renal cortical NHE3 mRNA and protein abundance (Baum et al. 1995), whereas glucocorticoid deficiency in the neonatal rat attenuates the developmental increase in Na+/H+ exchanger activity but has no effect on NHE3 mRNA abundance (Gupta et al. 2001).