Effect of intraventricular acetylcholine and eserine on the metabolism of sheep

Acetylcholine (5 μg/kg) and eserine (5 μg/kg) injected into a lateral cerebral ventricle of sheep exposed to their critical environmental temperature resulted in an increase in oxygen consumption accompanied by shivering, an increase in rectal temperature, and an elevation in plasma free fatty acid concentration. Changes in respiratory quotient during this response suggested an increase in the metabolism of fat. Acetylcholine and eserine similarly injected into sheep exposed to 10°C above their critical environmental temperature resulted in an increase in oxygen consumption, an increase in rectal temperature and an elevation in plasma free fatty acid concentration. Changes in respiratory quotient during this response also suggested an increase in the metabolism of fat. Acetylcholine and eserine injected into panting sheep resulted in an increase in rectal temperature and an increase in the already elevated plasma free fatty acid concentration. There was no significant change in oxygen consumption and changes in respiratory quotient were inconclusive. These results indicate that central cholinergic stimulation of sympathetic nerves to the adipose tissue and adrenal medulla is not inhibited by warm reception.