Alterations in forebrain catecholamine metabolism produced by cerebellar lesions in the rat

Projections from the midline cerebellar nuclei to norepinephrine (NE) and dopamine (DA) cell groups in the brain stem have been demonstrated histologically. To determine if these connections are significant biochemically, unilateral electrolytic lesions were placed in either vermis or paravermis and levels of DA, NE and gamma-aminobutyric acid (GABA) were measured in each half of the forebrain at 1 1/2, 3 or 6 weeks. In the cerebral hemisphere ipsilateral to a vermis lesion, there was a decrease in NE levels at 3 and 6 weeks. Relative to the opposite side DA was also reduced at 3 and 6 weeks. Paravermal lesions caused a contralateral reduction in DA at 3 weeks but no change in NE. GABA was only slightly altered. These results suggest that the cerebellum can modify levels and turnover of catecholamines in the brain, possibly via direct anatomic connections as well as by functional interaction with catecholaminergic pathways.