Thyroid hormone induction of actin polymerization in somatotrophs of hypothyroid rats : Potential repercussions in growth hormone synthesis and secretion

摘要: Thyroid hormone was shown to induce actin cytoskeleton polymerization in hypothyroid astrocytes and osteoblastic cells by a nongenomic mechanism. Polyadenylation of GH mRNA, process that depends on cytoskeleton-associated proteins, also be regulated thyroid hormone. Here we investigated histochemistry immunohistochemistry whether acute (100 microg per 100 g body weight, iv, for 30 min) or chronic (5 ip, 5 d) administration T3 thyroidectomized (Tx) sham-operated rats affects the somatotrophs F-actin arrangement its potential repercussion synthesis secretion. Thyroidectomy dramatically decreased amount content induced disassembly cytoskeleton. These effects were reversed T3. In addition, Tx rat somatotrophs, labeling detected mostly at cell periphery. After min administration, periphery increased perinuclear region, suggesting secretion stimulated No differences total protein content, although decrease F- increase G-actin contents pituitaries, panorama treatment, as Western blotting analysis. The animals' only mildly affected administration. results indicate T3-induced rapid alterations somatotroph cellular distribution resulted from filaments rearrangement, which characterizes action.