Influence of noradrenergic input into the hypothalamic paraventricular nucleus on fever in the guinea-pig.
The febrile response of guinea-pigs to a bacterial pyrogen was tested under different experimental conditions: (1) during electrical stimulation of the hypothalamic paraventricular nucleus (PVN), (2) after destruction of noradrenergic afferents into the PVN by 6-hydroxydopamine (6-OHDA), (3) during a microinfusion of noradrenaline (NA) into the PVN. Electrical stimulation of the PVN neurons by implanted microelectrodes reduced the febrile response to 45% of the control values. This confirmed the proposed antipyretic function of these neurons. Chronic destruction of noradrenergic afferents to the PVN by microinjected 6-OHDA also resulted in a significant reduction of febrile responses to 38% of the control values. A microinfusion of NA into the PVN enhanced the febrile responses to bacterial endotoxin by 39% in comparison to animals microinfused with the solvent (0.9% NaCl). Immunoreactivity to an antiserum against arginine vasopressin (AVP) was compared in PVN neurons of 6-OHDA-treated and of control animals. The number of AVP-immunoreactive perikarya and the intensity of immunoreactivity were increased in the animals treated with 6-OHDA, especially in the medial part of the PVN. Since fever was increased by microinfused NA and decreased by 6-OHDA treatment, we assume an inhibitory influence of noradrenergic brain stem afferents on the proposed antipyretic vasopressinergic system of the PVN.
Unger
M
M
Physiologisches Institut, Klinikum der Justus-Liebig-Universität, Giessen, Federal Republic of Germany.
Merker
G
G
Roth
J
J
Zeisberger
E
E
D000344:Afferent Pathways / Q000503:physiopathology; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D001831:Body Temperature; D004558:Electric Stimulation; D005260:Female; D005334:Fever / Q000503:physiopathology*; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D016627:Oxidopamine / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism / Q000503:physiopathology*
D001127:Arginine Vasopressin; D016627:Oxidopamine; D009638:Norepinephrine