INVOLVEMENT OF THE PARAVENTRICULAR NUCLEUS OF THE HYPOTHALAMUS (PVN) IN CARDIOVASCULAR AND AUTONOMIC MODULATION DURING LPS ENDOTOXEMIA IN AWAKE RATS

Abstract

During sepsis, areas of the central nervous system are activated and have a role in physiological adaptations to immunity challenge. The aim of this study was to evaluate the involvement of the paraventricular nucleus of the hypothalamus (PVN) on mean arterial pressure (MAP), heart rate (HR) and spectral analysis of HR variability (HRV) after administration of lipopolysaccharide (LPS) in conscious rats. Male Wistar rats were anesthetized for implantation of guide cannulae to the PVN. After 5 days the rats were anesthetized for chronic catheterization of the femoral artery and vein. 24 hours later it was performed in bilateral PVN of conscious rats, microinjection of 100 nl of saline or muscimol followed by LPS (iv). Cardiovascular parameters were analyzed by 2 hours. Saline microinjection did not modify the baseline parameters and after LPS was observed hypotension and tachycardia (Δ MAP= −35 ± 9 mmHg, Δ HR = 31 ± 14 bpm). Muscimol microinjection caused less decrease in MAP and a higher increase in HR (ΔMAP=−1±9 mmHg, ΔHR=122±31 bpm). The HRV was abolished during sepsis (Basal = 58.25 ± 15.95; Sepsis = 4.67 ± 1.61) and was not different for arterial pressure. Muscimol did not alter HRV in sepsis, but decreased the variability of BP (Saline = 20.04 ± 3.11; Muscimol = 10.93 ± 2.06). Our data suggest an involvement of PVN in cardiovascular and autonomic modulation during the initial phase of sepsis by LPS.