Fluid and electrolyte homeostasis is integral to blood pressure regulation. However, the central molecular mechanisms regulating the neural control of sodium excretion remain unclear. We have previously demonstrated brain Gαi2-subunit protein gated-pathways mediate the natriuretic response evoked by α2-adrenoceptor activation in-vivo. Consequently, we examined the role of brain Gαi2-proteins in the neural mechanisms facilitating fluid and electrolyte homeostasis in response to an acute i.v. 5% bodyweight volume expansion (VE) in conscious Sprague-Dawley (SD) rats (N=6/group). Compared to a control scrambled (SCR) oligodeoxynucleotide (ODN), Gαi2 ODN mediated down-regulation of brain Gαi2 proteins abolished the renal sympathoinhibitory response (peak ΔRSNA [% control] SCR 47±5 vs. Gαi2 94±8, P<0.05) and attenuated the natriuresis (peak ΔUNaV [µeq/µl] SCR 45 ±6 vs. Gαi2 25±4, P<0.05) to an i.v. VE. Confirming the role of brain Gαi2 proteins in the regulation of RSNA Gαi2 ODN pre-treatment failed to alter the natriuretic response to an i.v. VE in bilaterally renal denervated (RDNX) rats. Extending these studies beyond an acute experimental paradigm we have examined the role(s) of central Gαi2 proteins in fluid & electrolyte homeostasis and blood pressure regulation following elevated dietary salt-intake – which is known to evoke salt-sensitive hypertension in the Dahl salt-sensitive (DSS) rat. In response to a 21-day high salt (HS) challenge (8% NaCl diet) to fluid & electrolyte homeostasis we observed a site specific increase in hypothalamic paraventricular nucleus (PVN) Gαi2 protein levels in “salt-resistant” SD and Dahl Salt-Resistant rats (5.8 fold, and 7.6 fold respectively, P<0.05) that was not observed in DSS rats (N=6/group). In SD rats ODN-mediated prevention of Gαi2 up-regulation in the brain caused renal nerve-dependent sodium & water retention (24h Na+ balance [meq] SCR + HS 0.3±0.1, Gαi2 + HS 2.9±0.3*, Gαi2 RDNX + HS 0.8±0.4), global sympathoexcitation (plasma NE [nmol/L] SCR + HS 49±5, Gαi2 + HS 98±8*, Gαi2 RDNX + HS 73±5) and salt-sensitive hypertension (MAP [mmHg] SCR + HS 128±3, Gαi2 + HS 147±3*, Gαi2 RDNX + HS 132±2) (N=6/group). In these animals we observed no difference in the parasympathetic or sympathetic control of heart rate following i.v. atropine (1mg/kg) or propranolol (1mg/kg) administration (N=6/group). Ganglionic blockade with hexamathonium (30mg/kg i.v.) resulted in a significantly greater reduction in blood pressure in Gαi2-ODN infused rats faced with a high salt challenge indicating elevated sympathetic nervous system activity contributes to the hypertension observed in this group (N=6/group). In DSS rats chronic central Gαi2 protein down-regulation significantly exacerbated the magnitude of hypertension (MAP [mmHg] SCR + HS 164±3 vs. Gαi2 + HS 187±3*), sodium retention and global sympathoexcitation (plasma NE [nmol/L] SCR + HS 88±8 vs. Gαi2 + HS 115±9*) in response to 21-days of HS intake (N=6/group). ODN-mediated PVN specific Gαi2 down-regulation, but not i.c.v. miss-injection or PVN SCR ODN pre-treatment, caused sodium retention, global sympathoexcitation (plasma norepinephrine [nmol/L] i.c.v. Gαi2 + HS 20±4, PVN Gαi2 + HS 75±9τ) and hypertension (MAP [mmHg] i.c.v. Gαi2 + HS 127±3, PVN Gαi2 + HS 143±4τ) in Sprague-Dawley rats maintained on a high salt intake for 7-days (N=6/group). Owing to the location of the Gαi2 gene on chromosome 8, which is implicated in DSS rat hypertension, we believe the Gαi2 gene is a new target for rat genomic models investigating the pathophysiology of hypertension. Therefore, from multiple animal models we conclude that PVN Gαi2 protein-gated pathways represent a central molecular pathway acting to regulate renal nerve-dependent sodium excretion to facilitate sodium homeostasis and maintenance of a salt-resistant phenotype. Owing to a report linking SNP’s in the GNAI2 gene to hypertension in human subjects we speculate that our findings may have wider significance in relation to the long-term regulation of blood pressure and fluid and electrolyte homeostasis. R01HL107330. *p<0.05 vs. SCR + HS, τp<0.05 vs. i.c.v. Gαi2 + HS.