HEXAMETHYLENEBISACETAMIDE (HMBA) PREVENTS THE LOSS OF TSH SENSITIVITYIN PORCINE THYROID MONOLAYER CELLS

The polar compound hexamethylenebisacetamide (HMBA) is a differentiati ng agent in the murine erythroleukemia cell system (MELC). It induces, like dimethylsulfoxide, the commitment to terminal differentiation le ading to a recovery in the expression of several genes like the globin gene. This molecule which also induces differentiation in other cellu lar types is a growth agent for human, ovine and porcine thyroid cells . Forty-eight hours after the onset of culture, porcine thyroid monola yer cells do not respond to thyrotropin (TSH) We demonstrate that a pr etreatment from the onset of culture with HMBA of porcine thyroid cell s prevents the loss of TSH-sensitivity. The TSH-sensitivity is concent ration-dependent in HMBA and leads to the reorganization of cells into follicles, even in the presence of HMBA. However, the withdrawal of H MBA when TSH is added is absolutely required to obtain a total recover y in iodide trapping and organification. If HMBA is present during TSH -stimulation, it inhibits iodide trapping partially but iodide organif ication completely.