Axonal proliferation following lesions of cerebellar peduncles. A combined fluorescence microscopic and radioautographic study

The hippocampus and the cerebellar cortex, two terminal fields of N. locus coeruleus (LC), contain increased adrenergic innervation 30 days after partial lesions of the superior cerebellar peduncle (SP). The qualitative observation of enhanced terminal fluorescence after lesioning was confirmed by counting terminals in the hippocampus and cerebellum labeled by radioautography after injection of 3H‐proline into LC of the rat. Use of the Vibratome method for catecholamine‐fluorescence permitted the observation of both fluorescence and labeled terminals in sections from the same animal. The increased terminal density in the hippocampus following partial SP lesions suggests that this growth may be initiated by retrograde changes within LC neurons or collaterals of the cut axons and does not require a prior denervation of the post synaptic cells.