Cholecystokinin-8 promotes recovery of sympathectomy induced by 6-hydroxydopamine in adult mice.

We used an experimental model of sympathetic neuropathy to investigate the effects of intraperitoneal cholecystokinin-8 (CCK-8) administration on the recovery of injured peripheral neurones. After treatment of adult mice with 6-hydroxydopamine (6-OHDA), which known to induce peripheral sympathectomy, nerve growth factor (NGF) in peripheral tissue first increased and then rapidly decreased to baseline levels. Following this observation, sympathectomised mice were treated with CCK-8 starting when the NGF levels lowered toward the control value. Our results show that injections with 8 nmol/kg of CCK-8 promote not only recovery of noradrenergic innervation but also NGF and neuropeptide Y (NPY) synthesis in peripheral tissue. This latter observation suggests that the effect of CCK-8 might be mediated through the stimulation of NGF synthesis.