title: Non-genomic effect of L-triiodothyronine on calmodulin-dependent synaptosomal protein phosphorylation in adult rat cerebral cortex.
abstract: The present study was undertaken to examine calmodulin-dependent effect of thyroid hormones (THs) on synaptosomal protein phosphorylation in mature rat brain. Effect of L-triiodothyronine (L-T3) on in vitro protein phosphorylation was measured in a hypotonic lysate of synaptosomes prepared from adult male rat cerebral cortex, incubated in presence and absence of calcium ion (Ca2+) and calmodulin. L-T3 significantly enhanced incorporation of 32P into synaptosomal proteins as compared to basal level of phosphorylation in the presence of Ca2+ and calmodulin. Under these conditions, increase in protein phosphorylation was 47, 74 and 52% for 10 nM, 100 nM and 1 microM L-T3, respectively. Chelation of Ca2+ using ethylene glycol-bis (2-aminoethylether)-N, N, N', N'-tetraacetic acid (EGTA) inhibited the effects of Ca2+/calmodulin on TH-stimulated protein phosphorylation levels. This study suggests that a high proportion of L-T3-stimulated protein phosphorylation involves Ca2+/calmodulin-dependent pathways in adult rat cerebrocortical synaptosomes.
authors: Department of Basic Sciences, Parker College of Chiropractic, 2500 Walnut Hill Lane, Dallas, Texas 75229, USA. psarkar@parkercc.edu
authors: Pradip K
authors: PK
authors: Sarkar
authors: Jason J
authors: JJ
authors: Morris
authors: Joseph V
authors: JV
authors: Martin
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D014284:Triiodothyronine / Q000494:pharmacology*
chemical_list: D002147:Calmodulin; D009419:Nerve Tissue Proteins; D014284:Triiodothyronine; D002118:Calcium