Effect of cysteamine on levels of somatostatin-like immunoreactivity and catecholamines and on electroencephalogram in the rat brain.

Cysteamine (CYS) is known to be a quite specific depletor of somatostatin in the rat brain. In the present study we investigated the effect of CYS (100 mg/kg, 300 mg/kg, subcutaneously) on levels of somatostatin-like immunoreactivity (SLI) in the brain and cerebrospinal fluid, on catecholamines in the cortex, and on spectral cortical electroencephalogram (EEG) of rat. SLI was decreased in both the cortex and the striatum (p less than 0.05) of CYS-treated rats, but no change was seen in SLI of CSF. Cortical levels of dopamine, noradrenaline and homovanillic acid were decreased (p less than 0.05) following administration of either dose of CYS. In EEG, during mobility both the frontal and occipital peak (Fp) and mean (Fm) frequencies were slowed (p less than 0.05). Frontally, the amplitude of the frequency bands 1.5-3Hz and 3-5Hz was increased (p less than 0.05). During immobility the Fp and Fm were also slowed. In frequency bands of 3-5Hz, 5-10Hz and 10-20Hz the amplitude was decreased (p less than 0.05), indicating that, in addition to theta frequency, the low voltage fast activity is also affected by CYS. According to our results, both the cortical intrinsic neurons containing somatostatin and also the ascending catecholaminergic systems are affected after the single administration of CYS concomittantly with, but not necessarily related to, changes in different frequency bands in EEG.