Beschreibung:
<jats:sec><jats:label /><jats:p>Cutaneous vasoconstriction is tonically regulated by preoptic neurons (Tanaka et al 2009, Am J. Physiol 296, R1248‐57) via a pathway that relays synaptically in the medullary raphé but not in the dorsomedial hypothalamus (Rathner et al 2008, Am J. Physiol 295, R343‐54). We sought to identify the preoptic neurons responsible for this function in 28 urethane‐anesthetized rats (1–1.5g/kg, i.v.). Extracellular unit recordings were made from 40 preoptic neurons that were antidromically activated by electrical stimulation in the medullary raphé. The neurons’ ongoing activity was measured during episodes where trunk skin and core temperatures were manipulated by passing cold or warm water through a jacket around the animal's trunk. Frontal EEG was recorded at the same time. Seventeen preoptic‐raphé neurons were unresponsive to temperature, and a further four cells gave responses that were secondary to changes in EEG state. Seven preoptic‐raphé neurons behaved as expected for neurons regulating cutaneous vasonstriction: they were tonically active in warm conditions but were inhibited by cooling the trunk skin. Unexpectedly, twelve preoptic‐raphé neurons were activated by cooling the trunk skin. Both ‘warm’ and ‘cold’ preoptic neurons thus project directly to the medullary raphé, and we speculate that both contribute to the control of cutaneous vasoconstriction.</jats:p><jats:p>Supported by NHMRC</jats:p></jats:sec>