INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
artículos
Título:
Serotonergic system involvement in the inhibitory action of estrogen on induced sodium appetite in female rats
Autor/es:
DALMASSO, C., AMIGONE, J.L., VIVAS, L.
Revista:
PHYSIOLOGY AND BEHAVIOR
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Año: 2011 vol. 104 p. 398 - 407
ISSN:
0031-9384
Resumen:
This study of the participation of the serotonergic system in the inhibitory effect of estrogen on induced sodium
appetite in female rats explores sodiumappetite induced by Furosemide and lowsodiumdiet treatment (DEP) in
normally cycling rats and in ovariectomized rats with and without estradiol replacement (OVX, OVX+E2) .We
also analyzed the neural activity of serotonergic neurons of the dorsal raphe nucleus (DRN) aswell as the activity
of other brain nuclei previously found to be involved in sodium and water balance in sodium depleted animals
without access to the intake test. For this purpose,we examined the brain Fos, Fos-serotonin and Fos-vasopressin
immunoreactivity patterns in diestrus (D), estrus (E), OVX and OVX+E2 rats subjected to DEP.
Female rats in E and OVX+E2 exhibited a significant decrease in induced sodiumintake comparedwith females
in D and OVX. This estrogen-dependent inhibition on induced sodium appetite (approximately 50% reduction)
can be correlated with changes in Fos activation observed in the organum vasculosum of the lamina terminalis
(OVLT) and DRN, in response to sodium depletion. Given our previous observations in males, the expected
sodium depletion-induced activity of the OVLT was found to be absent in OVX+E2 females, while the usual
inhibitory tonic activity of serotonergic neurons of the DRN, instead of decreasing after sodium depletion,
increases or remains unchanged in OVX+E2-DEP and E-DEP females, respectively.
Regarding urinary water and sodium excretion 3 h after furosemide treatment, E-DEP and OVX+E2-DEP
animals excreted smaller volumes of more highly concentrated urine than depleted D and OVX rats. Twenty
hours after sodium depletion, the same groups of animals also showed a significant increase in the number of
Fos-AVP immunoreactive neurons within the supraoptic nucleus, compared with D-DEP.
In summary, our results demonstrate an estrogen-dependent inhibition of induced sodiumappetite in normally
cycling rats and ovariectomized animals with estradiol replacement, whichmay involve an interaction between
excitatory neurons of the OVLT and inhibitory serotonergic cells of the DRN. The main finding is thus
serotonergic system involvement as a possible mechanism in the inhibitory action of estrogen on induced
sodium appetite.