Respostas metabólicas e cardivasculares induzidas pela estimulação colinérgica no núcleo paraventricular do hipotálomo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The PVN is considered to be involved in cardiovascular and metabolic integration. The aim of this study was to assess if metabolic and cardiovascular adjustments that are controlled by the PVN are associated with cholinergic activity. We verified the effects of central cholinergic stimulation on plasma glucose, lactate and free fatty acids levels, and whether or not these effects are related to cardiovascular adjustments. Male Wistar rats weighing 250-300g received unilateral Carbachol (1, 2 and 6 nmol) or NaCl (100nL) microinjections through guide cannulae chronically implanted into the PVN. A jugular catheter was also chronically implanted for blood sampling, and polyethylene cannulae (PE-10) were inserted into the left femoral artery for cardiovascular monitoring. Each animal was the control of itself in different days, and the injection of carbachol or NaCl was randomly chosen. The PVN cholinergic stimulation increased, in a dose-dependent manner, mean blood pressure and plasma glucose levels, not affecting the mobilization of adipose tissue free fatty acids. Mean blood pressure increased 10 mmHg in the 1 nmol group and 13 mmHg in the 2nmol group on minute 7, remaining at high levels until minute 20, when its values started to fall. The 6 nmol dose induced a maintained 31 mmHg increase in mean pressure throughout the entire recording. Also on minute 7, the 1 nmol dose increased heart rate by 20 bpm. The 2 and the 6 nmol doses decreased heart rate respectively by 31 and 122 bpm, both with a relative time delay if compared to the time of increase in blood pressure. The 1, 2 and 6 nmol groups exhibited an increase in plasmatic glucose levels by 1,40 mM, 1,79 mM and 4,38 mM, respectively. Plasma glucose had a narrower correlation with blood pressure than with heart rate, its variation being probably due to a baroreflex. These data demonstrate that PVN cholinergic stimulation leads to an increase in specific sympathetic activity, as shown by the cardiovascular adjustments and the rise in the hepatic production of glucose, not followed by an increase in the mobilization of adipose tissue free fatty acids.

ASSUNTO(S)

mecanismos colinérgicos teses. fisiologia teses. hipotalamo teses.

ACESSO AO ARTIGO

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