Browsing by Subject "6-hydroxydopamine"

Laminins are a family of heterotrimeric glycoproteins found mainly in basement membranes. They interact with numerous other extracellular matrix components and cell surface receptors, including integrins and α-dystroglycan. Laminins play roles in myriad of functions including tissue morphogenesis, organogenesis, maintenance of tissue integrity and compartmentalization. In central nervous system laminins are involved in every major developmental stage from neural tube closure to synaptogenesis. Laminin expression in central nervous system decreases after maturation but has been found inducible by injury after trauma or disease. Since laminins are known to promote neurite outgrowth and neuronal survival, this has been proposed as a regenerative response to injury. Although the effects of endogenous laminin are clearly inadequate for repair, laminin based compounds could be powerful therapeutic agents. In previous in vivo studies KDI-tripeptide, a neurite outgrowth promoting fragment from γ1-laminin, has proved effective neuroprotective and regeneration promoting compound. Encouraged by these results I set out to test whether KDI would rescue midbrain dopaminergic neurons in unilateral 6-hydroxydopamine-induced rat model of Parkinson's disease. KDI (1-30µg) was injected to the striatum six hours prior to 6-hydroxydopamine. The severity of the lesion was then evaluated by measuring D-amphetamine induced rotation 2, 4 and 6 weeks postlesion and by assessing the number of neurons in substantia nigra pars compacta and optical density of striatum after tyrosine hydroxylase immunostaining at week seven. The only effective KDI dose studied was 3 µg. Compared to control it decreased Damphetamine induced rotational behaviour significantly at week four. KDI, however, failed to save tyrosine hydroxylase positive dopaminergic neurons in substantia nigra pars compacta or their axons in striatum. KDI might be usable in treating Parkinson's disease but it's mode of action doesn't appear to rely on protecting dopaminergic neurons or promoting the branching of their axons. KDI is known to inhibit ionotropic glutamate receptors and could therefore improve motor function by opposing striatal denervation induced overactivity of glutamatergic subthalamic nucleus neurons.