Guanosine 3'5'-monophosphate (cyclic GMP) and N2-2'-O-dibutyryl guanosine 3',5'-monophosphate (db cyclic GMP) have been injected into the third cerebral ventricle (i.c.v.) of the unanaesthetized cat and the effects on rectal temperature and on behavioural and autonomic activities observed and compared with those of acetylcholine and physostigmine. Acetylcholine (100nmol) and physostigmine (100nmol) injected together i.c.v. produced a rise in body temperature in cats at an environmental temperature of 20-24°C, which was abolished by pretreatment i.c.v. with atropine (200nmol). Cyclic GMP and db cyclic GMP (10-1250nmol) had no effect on body temperature in cats at an environmental temperature of 20-24'C but produced hypothermia (1250nmol) in cats at an environmental temperature of 9-11°C. The O-somatic antigen of Shigella dysenteriae (20μg/kg i.v.) produced fever in cats which was not potentiated by caffeine (25mg/kg i.p.). Levels of endogenous cyclic GMP in c.s.f. taken from the cisterna magna during fever induced by bacterial endotoxin in the presence or absence of paracetamol (50mg/kg i.p.) and/or caffeine were similar to values for afebrile cats. It is concluded that exogenous cyclic GMP and db cyclic GMP can inhibit central events mediating autonomic and behavioural thermoregulation stimulated in cats by exposure to cold environments.
|Number of pages||8|
|Journal||British Journal of Pharmacology|
|Publication status||Published - 1981|