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Alpha-MSH stimulates neurite outgrowth of neonatal rat corticospinal neurons in vitro

1996; Elsevier BV; Volume: 736; Issue: 1-2 Linguagem: Inglês

10.1016/0006-8993(96)00700-7

1872-6240

Elbert A.J. Joosten, Sandra Verhaagh, Didier Martin, Pierre A. Robe, Rachelle Franzen, Michel J. J. Hooiveld, Robert P. Doornbos, P.R. Bär, Gustave Moonen,

Neuropeptides and Animal Physiology

Peptides related to melanocortin (a MSH) and corticotropin (ACTH), collectively termed melanocortins, exert trophic effects on the outgrowth of neurites from peripheral and central nervous system in vitro. Here we study the neurite outgrowth promoting effect of α-MSH on corticospinal (CS) neurons in vitro. Corticospinal neurons were identified in cell culture of neonatal rat cortex by immunostaining of cholera toxin subunit B (CTB), retrogradely transported from the cervical parts of the spinal cord. The CTB-immunoreactive neurons represent a small percentage (3–5%) of the total cell population after 72 h in vitro. The axons or dendrites of cortical and CTB-labelled layer V neurons were visualized using antibodies against axon- or dendrite-specific markers and measured using a semi-automatic quantification device. Here we report that α-MSH stimulates axonal as well as dendrite outgrowth from both total and CTB-labelled neurons with a bell-shape response curve. Axonal outgrowth of CTB-labelled neurons was dose-dependently stimulated with a maximal effect of 50% at 10−10 M ot-MSH. The maximal effect for stimulation of axon outgrowth for the total cortex population was observed at 10−8 M α-MSH. In addition dendrite outgrowth of both total and CTB-labelled neurons is stimulated in a dose-dependent manner with maximal effects (varying between 46 and 48%) at 10−8 M a-MSH. Explanations in the shift for the optimal α-MSH concentration for stimulation of axonal outgrowth of CTB-labelled layer V neurons as compared to total cortex neurons are discussed.