Inhibition of salt appetite in sodium-depleted rats by carvacrol: Involvement of noradrenergic and serotonergic pathways.

Carvacrol, a monoterpene phenol present in the essential oil of oregano, possesses several biological properties, such as antioxidant, anti-inflammatory, anxiolytic, anticonvulsive and antinociceptive. In vitro studies have shown that carvacrol inhibits serotonin, noradrenaline and dopamine transporters and the enzymes monoamine oxidase-A and B. Different brain functions are controlled by monoamines, including cardiovascular control, thirst and sodium appetite. In the present study we investigated the effects of intracerebroventricular (i.c.v.) injection of carvacrol on sodium appetite, and the participation of brain serotonergic and noradrenergic pathways on carvacrol effects. Neuronal activation in homeostasis-related brain areas induced by i.c.v. injection of carvacrol was also evaluated. Carvacrol dose-dependently inhibited hypertonic saline intake (1.5%) in sodium-depleted rats, and this antinatriorexigenic effect was reduced by brain serotonergic depletion and by alpha-adrenergic blockade. Furthermore, i.c.v. injections of carvacrol significantly increased the neuronal activation in brain areas involved in the control of salt appetite, such as MnPO, OVLT, PVN, SON, CeA and MeA. Taken together, our data show that carvacrol presents antinatriorexigenic activity through serotonin and noradrenaline pathways within brain circuits involved in the modulation of the body fluid homeostasis.