Metabotropic glutamate receptor mGluR2/3 immunoreactivity in the mouse superior colliculus: co-localization with calbindin D28K

WE have studied the distribution of mGluR2/3 in the mouse superior collicul us (SC) with antibody immunocytochemistry and the effect of enucleation on this distribution. We also compared this labeling to that for calbindin D28 K. Anti-mGluR2/3-immunoreactive (IR) cells formed distinctive laminar patte rns within the lower optic and upper intermediate gray layers. By contrast, anti-calbindin D28K-IR cells formed obvious laminar patterns in three laye rs: one within the zonal and upper superficial gray layers, a second within the optic and intermediate gray layers, and the third within the deep gray layer. The distribution of mGluR2/3 IR cells thus matches the second layer of calbindin D28K cells. Two-color immunofluorescence revealed that more t han half (52.5%) of mGluR2/3-IR cells were also labeled with antibody to ca lbindin D28K. The majority of mGluR2/3-IR cells were small to medium-sized round/oval or stellate cells. Immunoreactivity for mGluR2/3 was clearly red uced in the contralateral SC following unilateral enucleation. The present results show that mGluR2/3 has a unique cellular sublaminar organization in SC that includes some calbindin D2SK-IR cells. The effects of enucleation suggest that the retinal projection may control the expression of mGluR2/3 in some cells in the mouse SC. (C) 1999 Lippincott Williams & Wilkins.