Regulation of prolactin mRNA by 1,25-dihydroxyvitamin D3 in GH4C1 cells

Abstract

GH4C1 cells, which possess specific cytosolic binding for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), have previously been found to respond to this hormone with a highly selective increase in prolactin synthesis. Here we extend our previous observations by measuring the effect of 1,25-(OH)2D3 on the accumulation of specific mRNA in GH4C1 cells using cytoplasmic dot by hybridization. In a hormone-free, chemically defined medium containing 0.4 mM Ca2+, stimulation of prolactin mRNA accumulation was 200-215% of control after 96 h of treatment with 1 x 10-9 M 1,25-(OH)2D3. Thyrotropin-releasing hormone (1 x 10-7 M) caused a similar increase in prolactin mRNA (206% of control). Neither hormone incre..