Medial septal area ANG II receptor subtypes in the regulation of urine and sodium excretion induced by vasopressin.

Introduction: The present study was designed to determine the effects of selective antagonists of angiotensin II receptor types AT(1) and AT(2) on the flow of urine and sodium excretion induced by arginine vasopressin (AVP).

Materials And Methods: To this end, the drugs were microinjected into the medial septal area (MSA) of the brains of male Holtzman rats. Intravenous infusion of hypotonic saline was used to promote urinary flow, which was collected for one hour.

On a possible dual role for the lateral septal area 5-HT(1A) receptor system in the regulation of water intake and urinary excretion.

The 5-hydroxytryptamine (5-HT)(1A) receptor system plays a prominent role in a variety of physiological functions and behavior and regulation of this responsiveness of the receptor system has been implicated in the central regulation of water intake and urinary excretion. The lateral septal area (LSA) exhibits a high density of 5-HT(1A) receptors, as well as a subpopulation of oxytocin (OT) receptors. Here we report the effects of pMPPF (a selective 5-HT(1A) antagonist), d(CH(2))(5)[Tyr(Me)(2)Thr(4), Orn(5), Tyr(NH(2))(9)]-vasotocin (an OT antagonist), and that 5-HT(1A) receptor system is regulated as a consequence of activation of the Na(+) channel by veratridine.

Role of serotonergic 5-HT1A and oxytocinergic receptors of the lateral septal area in sodium intake regulation.

Several reports have revealed a high density of 5-HT(1A) receptors in the lateral septal area (LSA), as well as a subpopulation of oxytocin (OT) receptors. Increasing evidence shows that 5-HT(1A) and OT neurons inhibit sodium urinary excretion. The aim of this study was to investigate the part played by serotonergic (5-HT(1A)) and oxytocinergic receptors in the LSA in the sodium intake induced in rats by sodium depletion followed by 24h deprivation.

Vasopressin and angiotensin receptors of the medial septal area in the control of mean arterial pressure induced by vasopressin.

Introduction: Brain arginine( 8)-vasopressin (AVP), through the V(1a)- and V(2)-receptors, is essential for the maintenance of mean arterial pressure (MAP). Central AVP interacts with the components of the renin-angiotensin system, which participate in MAP regulation. This study aimed to determine the effects of V(1a)-, V(2)- and V(1a)/V(2)-AVP selective antagonists and AT(1)- and AT(2)-angiotensin II (Ang II) selective antagonists on the MAP induced by AVP injected into the medial septal area (MSA) of the brain.

Subfornical organ mediates pressor effect of angiotensin: Influence of nitric oxide synthase inhibitors, AT(1) and AT(2) angiotensin antagonist's receptors.

We investigated the influence of voltage-dependent calcium channels and nitric oxide (NO) on angiotensin II (ANG II)-pressor effect injected into subfornical organ (SFO). The influence of NO on nifedipine antipressor action has also been studied by utilizing N(W)-nitro-L-arginine methyl ester (L-NAME) (20 mug x 0.2 mul(-1)) a nitric oxide synthase inhibitor (NOSI) and 7-nitroindazole (7-NIT) (20 mug x 0.

Nitric oxide and angiotensin II receptors mediate the pressor effect of angiotensin II: a study in conscious and zoletil-anesthetized rats.

Background: The circumventricular structures of the central nervous system and nitric oxide are involved in arterial blood pressure control, and general anesthesia may stimulate the central renin-angiotensin system. We therefore investigated the central role of angiotensin II and nitric oxide on the regulation of systemic arterial blood pressure in conscious and anesthetized rats.

Methods: Rats with stainless steel cannulae implanted into their lateral ventricle were studied.

Vasopressin and angiotensin receptors of the medial septal area of the brain in the control of thirst and salt appetite induced by vasopressin in water-deprived and sodium-depleted rats.

In this study we investigated the influence of d(CH(2))(5)-Tyr (Me)-AVP (A(1)AVP) and [Adamanteanacatyl(1),D-ET-D-Tyr(2), Val(4), aminobutyril(6),A(8,9)]-AVP (A(2)AVP), antagonists of V(1) and V(2) arginine(8)-vasopressin (AVP) receptors, respectively, as well as the effects of losartan and CGP42112A, antagonists of angiotensin II (ANGII) AT(1) and AT(2,) receptors, respectively, on water and 0.3 M sodium intake induced by water deprivation or sodium depletion (furosemide treatment) and enhanced by AVP injected into the medial septal area (MSA). A stainless steel cannula was implanted into the medial septal area (MSA) of male Holtzman rats AVP injection enhanced water and sodium intake in a dose-dependent manner.

Activation of paraventricular nucleus of hypothalamus 5-HT1A receptor on sodium intake.

Hypothalamic paraventricular nucleus (PVN) has an important role in the regulation of water and sodium intake. Several researches described the presence of 5-HT(1) receptors in the central nervous system. 5-HT(1A) was one of the prime receptors identified and it is found in the somatodendritic and post-synaptic forms.

L-type calcium channels mediate water intake induced by angiotensin injection into median preoptic nucleus.

Calcium ions are widely accepted as critically important in responses of neurons to a stimulus. We have show previously the central involvement of angiotensin II (ANGII) in water intake. This study determined whether voltage-dependent calcium channels are involved in ANGII-induced behavioral drinking implicating nitrergic mechanism.

Interaction between arginine vasopressin and angiotensin II receptors in the central regulation of sodium balance.

We speculated that the influence of lateral preoptic area (LPO) in sodium balance, involves arginine8-vasopressin (AVP) and angiotensin (ANG II) on Na+ uptake in LPO. Therefore, the present study investigated the effects of central administration of specific AVP and ANG II antagonists (d(CH2)5-Tyr (Me)-AVP (AAVP) and [Adamanteanacetyl1, 0-ET-d-Tyr2, Val4, Aminobutyryl6, Arg(8,9)]-AVP (ATAVP) antagonists of V1 and V2 receptors of AVP. Also the effects of losartan and CGP42112A (selective ligands of the AT1 and AT2 angiotensin receptors, respectively), was investigated on Na+ uptake and renal fluid and electrolyte excretion.

Interaction between paraventricular nucleus and medial septal area on the renal effects induced by adrenaline.

The aim of the present study was to analyze the role of alpha1, alpha2-adrenoceptors, and the effects of losartan and PD123319 (selective ligands of the AT1 and AT2 angiotensin receptors, respectively) injected into the paraventricular nucleus (PVN) on the diuresis, natriuresis, and kaliuresis induced by administration of adrenaline into the medial septal area (MSA). Male Holtzman rats with a stainless steel cannula implanted into the MSA and bilaterally into the PVN were used. The administration of adrenaline into the MSA increased in a dose-dependent manner the urine, sodium, and potassium excretions.

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.

Male Holtzman rats weighting 200-250 g were anesthetized with zoletil 50 mg/Kg (tiletamine chloridrate 125,0 mg and zolazepan chloridrate 125,0 mg) into quadriceps muscle and submitted an electrolytic lesion of the lateral hypothalamus (LH) and a stainless steel cannula was implanted into their median preoptic nucleus (MnPO). We investigated the effects of the injection into the (MnPO) of FK 409 (20 microg/0.5 microl), a nitric oxide (NO) donor, and N(W)-nitro-L-arginine methyl ester (L-NAME) 40 microg/0.

Influence of arginine vasopressin receptors and angiotensin receptor subtypes on the water intake and arterial blood pressure induced by vasopressin injected into the lateral septal area of the rat.

In this study we investigated the influence of d(CH2)5-Tyr(Me)-[Arg8]vasopressin (AAVP) and [adamanteanacetyl1,0-ET-d-Tyr2,Val4,aminobutyryl6,Arg8,9]-[Arg8]vasopressin (ATAVP), which are antagonists of vasopressin V1 and V2 receptors, and the effects of losartan, a selective angiotensin AT1 receptor antagonist, and CGP42112A, a selective AT2 receptor antagonist, injected into the lateral septal area (LSA) on thirst and hypertension induced by [Arg8]vasopressin (AVP). AAVP and ATAVP injected into the LSA reduced the drinking responses elicited by injecting AVP into the LSA. Both the AT1 and AT2 ligands administered into the LSA elicited a concentration-dependent decrease in the water intake induced by AVP injected into the LSA, but losartan was more effective than CGP42112A.

Effects of subtypes of adrenergic and angiotensinergic antagonists on the water and sodium intake induced by adrenaline injected into the paraventricular nucleus.

The present experiments were conducted to investigate the role of the alpha(1A)-, alpha(1B)-, beta(1)-, beta(2)-adrenoceptors, and the effects of losartan and CGP42112A (selective ligands of the AT(1) and AT(2) angiotensin receptors, respectively) on the water and sodium intake elicited by paraventricular nucleus (PVN) injection of adrenaline. Male Holtzman rats with a stainless steel cannula implanted into the PVN were used. The ingestion of water and sodium was determined in separate groups submitted to water deprivation or sodium depletion with the diuretic furosemide (20 mg/rat).

Effects of V1 and angiotensin receptor subtypes of the paraventricular nucleus on the water intake induced by vasopressin injected into the lateral septal area.

In this study, we investigated the influence of d(CH(2))(5)-Tyr (Me)-AVP (AAVP) an antagonist of V(1) receptors of arginine(8)-vasopressin (AVP) and the effects of losartan and CGP42112A (selective ligands of the AT(1) and AT(2) angiotensin receptors, respectively) injections into the paraventricular nucleus (PVN) on the thirst effects of AVP stimulation of the lateral septal area (LSA). AVP injection into the LSA increased the water intake in a dose-dependent manner. AAVP injected into the PVN produced a dose-dependent reduction of the drinking responses elicited by LSA administration of AVP.

Influence of angiotensin II receptor subtypes of the paraventricular nucleus on the physiological responses induced by angiotensin II injection into the medial septal area.

Objective: We determined the effects of losartan and PD 123319 (antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar1, Ala8] ANG II (a relatively peptide antagonist of angiotensin receptors) injected into the paraventricular nucleus (PVN) on water and 3% NaCl intake, and the diuretic, natriuretic, and pressor effects induced by administration of angiotensin II (ANG II) into the medial septal area (MSA) of conscious rats.

Methods: Holtzman rats were used. Animals were anesthetized with tribromoethanol (20 mg) per 100 grams of body weight, ip.

Novel evidence that nitric oxide of the medial septal area influences the salivary secretion induced by pilocarpine.

Our studies have focused on the effect of injection of L-NAME and sodium nitroprussiate (SNP) on the salivary secretion, arterial blood pressure, sodium excretion and urinary volume induced by pilocarpine which was injected into the medial septal area (MSA). Rats were anesthetized with urethane (1.25 g/kg b.