Inhibitory mechanism of the nucleus of the solitary tract involved in the control of cardiovascular, dipsogenic, hormonal, and renal responses to hyperosmolality.
The nucleus of the solitary tract (NTS) is the primary site of visceral afferents to the central nervous system. In the present study, we investigated the effects of lesions in the commissural portion of the NTS (commNTS) on the activity of vasopressinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei, plasma vasopressin, arterial pressure, water intake, and sodium excretion in rats with plasma hyperosmolality produced by intragastric 2 M NaCl (2 ml/rat). Male Holtzman rats with 15-20 days of sham or electrolytic lesion (1 mA; 10 s) of the commNTS were used. CommNTS lesions enhanced a 2 M NaCl intragastrically induced increase in the number of vasopressinergic neurons expressing c-Fos in the PVN (28 ± 1, vs. sham: 22 ± 2 c-Fos/AVP cells) and SON (26 ± 4, vs. sham: 11 ± 1 c-Fos/AVP cells), plasma vasopressin levels (21 ± 8, vs. sham: 6.6 ± 1.3 pg/ml), pressor responses (25 ± 7 mmHg, vs. sham: 7 ± 2 mmHg), water intake (17.5 ± 0.8, vs. sham: 11.2 ± 1.8 ml/2 h), and natriuresis (4.9 ± 0.8, vs. sham: 1.4 ± 0.3 meq/1 h). The pretreatment with vasopressin antagonist abolished the pressor response to intragastric 2 M NaCl in commNTS-lesioned rats (8 ± 2.4 mmHg at 10 min), suggesting that this response is dependent on vasopressin secretion. The results suggest that inhibitory mechanisms dependent on commNTS act to limit or counterbalance behavioral, hormonal, cardiovascular, and renal responses to an acute increase in plasma osmolality.
Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil.
Graziela T
GT
Blanch
André H
AH
Freiria-Oliveira
David
D
Murphy
Renata F
RF
Paulin
José
J
Antunes-Rodrigues
Eduardo
E
Colombari
José V
JV
Menani
Débora S A
DS
Colombari
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D004326:Drinking / Q000502:physiology*; D007668:Kidney / Q000502:physiology*; D008297:Male; D009994:Osmolar Concentration; D010121:Oxytocin; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000378:metabolism*; D013495:Supraoptic Nucleus / Q000166:cytology; D014667:Vasopressins; D014883:Water-Electrolyte Imbalance / Q000378:metabolism*
D016760:Proto-Oncogene Proteins c-fos; D014667:Vasopressins; D010121:Oxytocin