Submitted on April 24, 2008
Revised on October 15, 2008
Accepted on October 15, 2008
The role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia
Feng Chen1, Melissa Dworak1, Yuliang Wang2, Joo Lee Cham1, and Emilio Badoer1*
1 RMIT University
2 Weifang Medical University
* To whom correspondence should be addressed. E-mail: emilio.badoer{at}rmit.edu.au.
The hypothalamic paraventricular nucleus (PVN) is an important integrative centre in the brain. In the present study we investigated whether the PVN is a key region in the mesenteric vasoconstriction that normally accompanies an increase in body core temperature. Anesthetized rats were monitored for blood pressure, heart rate, mesenteric blood flow and vascular conductance. In control rats, elevation of body core temperature to 41 oC had no significant effect on blood pressure, increased heart rate and reduced mesenteric blood flow by 21%. In a separate group of rats, muscimol was microinjected bilaterally (1nmol/side) into the PVN. Compared to the control group, there was no significant difference in the blood pressure and heart rate responses elicited by the increase in body core temperature. In contrast to control animals, however, mesenteric blood flow did not fall in the muscimol treated rats in response to the elevation in body core temperature. In a separate group, in which muscimol was microinjected into regions outside the PVN, elevating body core temperature elicited the normal reduction in mesenteric blood flow. The results suggest that the PVN may play a key role in the reflex decrease in mesenteric blood flow elicited by hyperthermia.
