Serotonergic mechanisms of the lateral parabrachial nucleus on DOCA-induced sodium intake.
It has been shown that the serotonergic mechanisms of the lateral parabrachial nucleus (LPBN) inhibit NaCl intake in different models of angiotensin II (ANG II)-dependent NaCl intake in rats. However, there is no information about the involvement of LPBN serotonergic mechanisms on NaCl intake in a model of NaCl intake not dependent on ANG II like deoxycorticosterone (DOCA)-induced NaCl intake. Therefore, in this study we investigated the effects of bilateral injections of serotonergic agonist and antagonist into the LPBN on DOCA-induced 1.8% NaCl intake in rats. Male Holtzman rats were treated with s.c. DOCA (10 mg/rat each every 3 days). After a period of training, in which the rats had access to 1.8% NaCl during 2 h for several days, the rats were implanted with stainless steel cannulas bilaterally into the LPBN. Bilateral injections of the serotonergic receptor antagonist methysergide (4 microg/0.2 microl each site) in the LPBN increased 1.8% NaCl intake (32.2+/-3.9 versus vehicle: 15.0+/-1.6 ml/2 h, n=10) and water intake (12.5+/-3.5 versus vehicle: 3.2+/-1.0 ml/2 h). Injections of the serotonergic 5HT(2A/2C) receptor agonist DOI (5 microg/0,2 microl each site) in the LPBN reduced 1.8% NaCl intake (6.8+/-1.7 versus saline: 12.4+/-1. 9 ml/2 h, n=10) and water intake (2.2+/-0.8 versus saline: 4.4+/-1.0 ml/2 h). Besides the previously demonstrated importance for the control of ANG II-dependent water and NaCl intake, the data show that the serotonergic inhibitory mechanisms of the LPBN are also involved in the control of DOCA-induced NaCl intake.
De Gobbi
J I
JI
Department of Physiology and Pathology, School of Dentistry, Paulista State University, UNESP, Rua Humaitá 1680, 14801-903 Araraquara, Sao Paulo, Brazil.
De Luca
L A
LA
Menani
J V
JV
D000662:Amphetamines / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002529:Cerebellar Nuclei / Q000187:drug effects / Q000502:physiology*; D003900:Desoxycorticosterone / Q000008:administration & dosage / Q000494:pharmacology*; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008784:Methysergide / Q000008:administration & dosage / Q000494:pharmacology*; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D012982:Sodium, Dietary
D000662:Amphetamines; D017366:Serotonin Receptor Agonists; D012982:Sodium, Dietary; D012701:Serotonin; D003900:Desoxycorticosterone; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; D008784:Methysergide