Recent investigations suggest a role for cyclic GMP in cerebellum as an important factor involved in the regulation of Purkinje cells activity. Since the formation of synapses in cerebellar Purkinje cell body of rat is complete only after the first 15 days of life, cGMP levels have been measured during development. Young adult and three day old rats have been used. The animals were killed by a beam of focused microwave radiation on the skull for 3 seconds. In the new born rat cerebellum the levels of cGMP are much lower than in adult animals. Harmaline, a potent and selective activator of the climbing fibers, a pathway which activates the onset of burst discharges in the Purkinje cells when injected in adult rats,induces, as it has been-previously shown, a 5 fold increase of the level of cerebellar cGMP. In contrast in new born rats harmaline does not increase cGMP concentrations. Moreover diazepam, which has been shown to decrease cerebellar cGMP levels in adult rats, does not appear to have such effect in new borns. On the other hand guanylate-cyclase activity is significantly higher in the new born rats in comparison with adults. Furthermore Harmaline injection in adult animals induces a stimulation of cerebellar guanylate-cyclase, as measured in vitro.
ASJC Scopus subject areas