title: Colocalization of somatostatin receptors with DARPP-32 in cortex and striatum of rat brain.
abstract: Somatostatin (SST)-positive medium-sized aspiny interneurons are selectively spared in excitotoxicity. The biological effects of SST are mediated via five different receptors, namely somatostatin receptor (SSTR)1-5; however, SSTR subtype spared in excitotoxicity and involved in neuroprotection is not known. Dopamine- and cAMP-regulated phosphoprotein (DARPP-32) is predominantly expressed in medium-sized projection neurons that are most vulnerable in excitotoxicity. In the present study, we determined the colocalization of SST and SSTRs with DARPP-32 in rat brain cortical and striatal regions using immunofluorescence immunohistochemistry. We also determined the expression of DARPP-32 in SSTR1-5 immunoprecipitate prepared from cortex and striatum. SST-positive neurons in cortex and striatum are devoid of colocalization with DARPP-32. However, in cortical and striatal brain regions, three different neuronal populations either expressing SSTRs and DARPP-32 alone or displaying colocalization were identified. Quantitative analysis reveals that in cortex and striatum, SSTR1 and 5 are most predominant receptor subtypes colocalized with DARPP-32 followed by SSTR4, 2, and 3 in cortex whereas SSTR2, 4, and 3 in striatum. Importantly, DARPP-32 is expressed in SSTR1-5 immunoprecipitate prepared from cortex and striatum. Taken together, these results provide the first evidence that the SSTR-positive neurons lacking colocalization with DARPP-32 might be spared in excitotoxicity.
authors: The University of British Columbia, Vancouver, BC, Canada, V6T 1Z3.
authors: Padmesh S
authors: PS
authors: Rajput
authors: Geetanjali
authors: G
authors: Kharmate
authors: Ujendra
authors: U
authors: Kumar
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000737:chemistry* / Q000648:ultrastructure; D003342:Corpus Striatum / Q000737:chemistry* / Q000648:ultrastructure; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000032:analysis*; D019084:Fluorescent Antibody Technique, Indirect; D047468:Immunoprecipitation; D008297:Male; D009474:Neurons / Q000737:chemistry*; D009498:Neurotoxins / Q000633:toxicity; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley; D017481:Receptors, Somatostatin / Q000032:analysis* / Q000145:classification; D013004:Somatostatin / Q000032:analysis
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009498:Neurotoxins; C497930:Ppp1r1b protein, rat; D017481:Receptors, Somatostatin; D013004:Somatostatin