Adrenoceptors of the medial septal area modulate water intake and renal excretory function induced by central administration of angiotensin II

Abstract

We investigated the role of α-adrenergic antagonists and clonidine injected into the medial septal area (MSA) on water intake and the decrease in Na + , K + and urine elicited by ANGII injection into the third ventricle (3rdV). Male Holtzman rats with stainless steel cannulas implanted into the 3rdV and MSA were used. ANGII (12 nmol/µl) increased water intake (12.5 ± 1.7 ml/120 min). Clonidine (20 nmol/ µl) injected into the MSA reduced the ANGII-induced water intake (2.9 ± 0.5 ml/120 min). Pretreatment with 80 nmol/µl yohimbine or prazosin into the MSA also reduced the ANGII-induced water intake (3.0 ± 0.4 and 3.1 ± 0.2 ml/120 min, respectively). Yohimbine + prazosin + clonidine injected into the MSA abolished the ANGIIinduced water intake (0.2 ± 0.1 and 0.2 ± 0.1 ml/120 min, respectively). ANGII reduced Na + (23 ± 7 µEq/120 min), K + (27 ± 3 µEq/120 min) and urine volume (4.3 ± 0.9 ml/120 min). Clonidine increased the parameters above. Clonidine injected into the MSA abolished the inhibitory effect of ANGII on urinary sodium. Yohimbine injected into the MSA also abolished the inhibitory effects of ANGII. Yohimbine + clonidine attenuated the inhibitory effects of ANGII. Prazosin injected into the MSA did not cause changes in ANGII responses. Prazosin + clonidine attenuated the inhibitory effects of ANGII. The results showed that MSA injections of α 1 -and α 2 -antagonists decreased ANGII-induced water intake, and abolished the Na + , K + and urine decrease induced by ANGII into the 3rdV. These findings suggest the involvement of septal α 1 -and α 2 -adrenergic receptors in water intake and electrolyte and urine excretion induced by central ANGII. Correspondence

Role of the serotoninergic system in the sodium appetite control

“…On the other hand, electric stimulation of renal nerve reduces natriuretic response through increase of the tubular sodium reabsorption (DiBona 2001). These observations were reinforced by evidence that central sympatholytic action induces an increase of the renal sodium excretion (Saad et al 2002).…”

Lateral hypothalamus lesions influences water and salt intake, and sodium and urine excretion, and arterial blood pressure induced by L-NAME and FK 409 injections into median preoptic nucleus in conscious rats

“…It has been demonstrated that intracebroventricular injection of N G -monomethyl-L-arginine (NMMA), a blocker of NOS, attenuated water intake (Kadekaro et al, 1994) and preferentially increased plasma concentration of oxytocin and vasopressin in rats deprived of water for 24 h (Liu et al, 1998). Water intake increased after sc administration of hypertonic saline was progressively reduced by L-NAME injected into the lateral ventricle (LV) (Saad et al, 2002c). NO-containing neurons have been localized in various parts of the central nervous system including hypothalamus, septal area, (Saad et al, 2002a,b,c;Yang and Voogt, 2002).…”

“…(Saad et al, 1999(Saad et al, , 2002c. Different data indicate that the MnPO is indeed the target of afferent from osmosensitive and barosensitive systems concerned with fluid homeostasis and cardiovascular regulation (Cunningham and Jonhnson, 1989;Gardiner and Stricker, 1985;Lind and Johnson, 1982).…”

“…Treatment with L-NAME increases blood pressure that is at least in part salt sensitive (Hodge et al, 2002). NO is involve in the regulation of drinking behavior induced by central administration of ANGII and cellular dehydration, and NO of the subfornical organ (SFO) play an important role in this regulation (Saad et al, 2002c). NO plays an important role in the hydro mineral and cardiovascular regulation (Saad et al, 2002c).…”

“…NO is involve in the regulation of drinking behavior induced by central administration of ANGII and cellular dehydration, and NO of the subfornical organ (SFO) play an important role in this regulation (Saad et al, 2002c). NO plays an important role in the hydro mineral and cardiovascular regulation (Saad et al, 2002c). There is considerable evidence indicating an important role for the receptors of the areas of the central nervous system in the control of water intake, electrolytic balance and cardiovascular regulation (Dorn et al, 1970;Camargo et al, 1976).…”