[Nle4,D-Phe7]alpha-MSH improves functional recovery in rats subjected to diencephalic hemisection.

Rats subjected to diencephalic hemisection were s.c. treated with alpha-MSH (20 micrograms/rat daily) or with [Nle4,D-Phe7]alpha-MSH (10 micrograms/rat every other day) for two weeks starting on day 3 after lesion. Apomorphine-induced (1 mg/kg s.c.) rotational behavior was studied on days 7, 14 and 21 after lesion, and a sensorimotor test battery was carried out on days 3, 10, 17 and 24 after lesion. [Nle4,D-Phe7]alpha-MSH greatly reduced rotational behavior and significantly improved sensorimotor performance. Histological studies showed that treatment with alpha-MSH and, even more markedly, with [Nle4,D-Phe7]alpha-MSH reduced the size of the lesion and the pseudoinflammatory reaction, and caused a marked proliferation and hypertrophy of astroglia. Binding studies showed that no supersensitivity of striatal dopamine receptors developed on the lesioned side of alpha-MSH- and [Nle4,D-Phe7]alpha-MSH-treated rats. The present results seem to further support the trophic role of MSH peptides on nerve tissue.