engleski

Regional differences in morphology of the striatal medium spiny neurons

Medium spiny projection neurons (MSNs) represent the most numerous neurons in the corpus striatum of mammals, birds and reptiles. Similar structure in different species makes them an essential organizational and functional role of the vertebrate brain. In the human brain, dysfunction of the striatal neurons leads to rather complex movement disorders and our complete understanding of the exact pathogenetic mechanisms is still needed. This led to the development of numerous animal models to study principles of striatal organization and pathology. The striatal complex is the site of convergence for a wide range of cortical and subcortical inputs so the dysfunction of any of those pathways can be expressed in various clinical presentations. In the mouse, the rostral part of striatum receives mainly cortical projections from limbic, central part from primary sensory-motor and caudal from associative parieto-occipital regions. We hypothesized that MSNs will show increase in morphological complexity from rostral to caudal part of striatum. Hence, by using Neurolucida system 162 striatal Golgi Cox impregnated MSNs from 15 adult mice where 3D-reconstructed and parameters of dendritic morphology where analyzed. For the purpose of the quantitative analysis neurons in the dorsal part of the central striatum where further divided in medial and lateral part, but no significant differences in dendritic morphology where observed between these two regions. Compared to the central part, MSNs in the caudal striatum had significantly higher tree complexity, 20% more segments and 30 % higher total dendritic length. In addition, the thickness of dendrites was also higher suggesting not only higher complexity but also higher functional activity of caudal MSNs. MSNs of rostral striatum have slightly less segments than in the central part, but have significantly higher total dendritic length (around 20%). Consequently, individual segments were 20-40% longer in the rostral compared to the other striatal regions. This is pointing at morphological specialization of MSNs in the limbic parts of striatum. Obtained data show that despite a uniform structure of mouse striatum there are important regional differences in their micro-circuitry structure. This should be considered in the research using various animal models studying diseases affecting the striatum. It is likely to expect even more pronounced regional differences in the morphology of MSNs in the human (primate) brain.

medium spiny neuron; striatum; speech; Foxp2

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