Sexual dimorphism in hypovolemic thirst induced by Furosemide and low sodium diet treatment (F/LSD).

LAURA VIVAS; ANA FABIOLA MACCHIONE; CAROLINA DALMASSO

San diego, CA

Congreso; EXPERIMENTAL BIOLOGY; 2008

In a two-bottle free choice test we investigated the F/LSD-induced water and 2% NaCl intake in female (F), ovariectomized (FOVX) and male rats (M). We also studied estrogen receptor a inmunoreactivity (ER-a ir) and Fos-ir in the subfornical organ (SFO) and median preoptic nucleus (MnPO), key areas involved in body fluid homeostasis. Before F/LSD treatment we found that salt preference (NaCl intake/ NaCl + water intake) in F and FOVX was higher compared to M (p<0.001). F/LSD-induced depletion increased water intake in F versus FOVX and M (p<0.001). However induced-sodium appetite was similar in all groups. In the SFO, F/LSD increased Fos expression in F and M, but decreased Fos-ir neurons in FOVX compared to non-depleted rats (p<0.001). Within the MnPO, Fos-ir of control animals was higher in M and FOVX compared to F (p<0.001). After F/LSD, Fos-ir did not change in F, however we observed a decreased activation in both M and FOVX (p<0.01). Regarding ER-a, F/LSD increased the expression along SFO and MnPO only in F (p<0.001). Besides, we found no differences after the treatment in both M and FOVX. Our data support previous evidence suggesting the MnPO as an inhibitor of water intake in males. We also shown the participation of ER-a along the SFO and MnPO after F/LSD treatment in females. In conclusion, we may suggest that hypovolemic thirst induced by F/LSD is a sexual dimorphic phenomenon. Supported by ANPCyT and CONICET.