title: Hydrogen peroxide attenuates the dipsogenic, renal and pressor responses induced by cholinergic activation of the medial septal area.
abstract: Cholinergic activation of the medial septal area (MSA) with carbachol produces thirst, natriuresis, antidiuresis and pressor response. In the brain, hydrogen peroxide (H2O2) modulates autonomic and behavioral responses. In the present study, we investigated the effects of the combination of carbachol and H2O2 injected into the MSA on water intake, renal excretion, cardiovascular responses and the activity of vasopressinergic and oxytocinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Furthermore, the possible modulation of carbachol responses by H2O2 acting through K+ATP channels was also investigated. Male Holtzman rats (280-320 g) with stainless steel cannulas implanted in the MSA were used. The pre-treatment with H2O2 in the MSA reduced carbachol-induced thirst (7.9±1.0, vs. carbachol: 13.2±2.0 ml/60 min), antidiuresis (9.6±0.5, vs. carbachol: 7.0±0.8 ml/120 min,), natriuresis (385±36, vs. carbachol: 528±46 μEq/120 min) and pressor response (33±5, vs. carbachol: 47±3 mmHg). Combining H2O2 and carbachol into the MSA also reduced the number of vasopressinergic neurons expressing c-Fos in the PVN (46.4±11.2, vs. carbachol: 98.5±5.9 c-Fos/AVP cells) and oxytocinergic neurons expressing c-Fos in the PVN (38.5±16.1, vs. carbachol: 75.1±8.5 c-Fos/OT cells) and in the SON (57.8±10.2, vs. carbachol: 102.7±7.4 c-Fos/OT cells). Glibenclamide (K+ATP channel blocker) into the MSA partially reversed H2O2 inhibitory responses. These results suggest that H2O2 acting through K+ATP channels in the MSA attenuates responses induced by cholinergic activation in the same area.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Melo
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: J V
authors.initials: JV
authors.lastname: Menani
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil. Electronic address: eduardo.colombari@foar.unesp.br.
authors.forename: E
authors.initials: E
authors.lastname: Colombari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil. Electronic address: deborac@foar.unesp.br.
authors.forename: D S A
authors.initials: DSA
authors.lastname: Colombari
mesh_terms: D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology*; D002408:Catheters, Indwelling; D002491:Central Nervous System Agents / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D004231:Diuresis / Q000187:drug effects / Q000502:physiology; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D004435:Eating / Q000187:drug effects / Q000502:physiology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D054086:KATP Channels / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010121:Oxytocin / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D020665:Septum of Brain / Q000187:drug effects* / Q000502:physiology; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000502:physiology; D013894:Thirst / Q000187:drug effects / Q000502:physiology; D014667:Vasopressins / Q000378:metabolism
chemical_list: D002491:Central Nervous System Agents; D018679:Cholinergic Agonists; D054086:KATP Channels; D016760:Proto-Oncogene Proteins c-fos; D014667:Vasopressins; D010121:Oxytocin; D002217:Carbachol; D006861:Hydrogen Peroxide
keywords: c-Fos; carbachol; forebrain; oxidative stress; vasopressin