Manganese neurotoxic time course is not influenced by l-deprenyl systemic treatment: Influence of l-deprenyl in manganese neurotoxic time course

Unilateral microinjection of manganese into the rat substantia nigra pars compacta (SNpc) leads to the death of nigral neurons and a decrease in dopamine (DA) within the ipsilateral striatum. l-deprenyl, an irreversible inhibitor of monoamine oxidase B, appears to protect or rescue dopaminergic nigral neurons from the toxic effects of 6-hydroxydopamine (6-OHDA) and 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropiridine (MPTP). In this study we aimed to investigate whether l-deprenyl is able to influence the manganese neurotoxic time course. l-deprenyl rescue activity was evaluated in discontinuous posology and its protective effect was evaluated in a continuous one. Apomorphine-induced rotational behavior and striatal tyrosine hydroxylase immunostaining (TH-IS) were evaluated in both conditions at 24 h, 72 h and 168 h after intranigral microinjections. Our results indicate a failure in l-deprenyl to influence the establishment and time course of rotational response to apomorphine. Strikingly, a further decrease in the tyrosine hydroxylase immunostaining, at 168 h post microinjection in l-deprenyl-treated rats was obtained. Our data revealed no correlation between an increasing rotational behavior and reduction in TH-IS.