Hyperglycaemia, a morphine-like effect produced by naloxone in the cat.

In unanaesthetized cats the pronounced hyperglycaemia produced by intravenous morphine (5 mg/kg) was inhibited by naloxone. However, naloxone itself produced hyperglycaemia when given in doses slightly larger than those required to produce inhibition. These two effects of naloxone were obtained when it was injected intravenously, into a lateral cerebral ventricle, or into the cisterna magna. The hyperglycaemia produced when naloxone or morphine was injected into a lateral cerebral ventricle or into the cisterna magna was not inhibited by intravenous naloxone. Hyperglycaemia was not the only morphine-like effect of naloxone. It also reproduced some of the behavioural effects of morphine.