Abstract
Nitric oxide (NO) is an un conventional intercellular messenger in the brain synthesised from L-arginine by a family of enzimes called NO syn thases (NOS). Recent studies have d emonstrated that NO plays a role in the control of dopamine release in rat striatum. Presumably, NOS inhibitors could decrease locomotor activity by interfering with striatal dopamin e. The aim of this study was to assess the effect of L-NOARG (90 mg/kg), a potent NOS in hibito r, on neuro nal p rotein synthesis activity in striatum of mice after subchronic administration for 4 consecutive days. Neuron al protein synthesis activity was analyzed by quantifyng nuclear areas and nu mber of silver-stained nucleolar organiser regions (Ag -NORs) per nucleus. These Ag-NORs may represen t the transcriptional activity of the cell. The sections of striatu m examined were silver stained according to the method described by Ploton et al. (1986). The results showed that mean number of Ag-NOR p er nucleus significantl y increased in the striatum of mice, as compared with the co ntrol group (p<0.0 5). These findings indicate th e existence of an increase in transcriptional activity after L-NOARG treatmen t, suggesting that the neostriatal dop aminergic innervation quickly develops tolerance to the interruption of dop amine transmission by L-NOARG.
