Abstract
The mitogenic effect of the hypothalamic peptides growth hormone-releasing factor (GRF) and somatostatin on cultured growth hormone (GH)-producing cells (somatotrophs) was studied. Using autoradiographic detection of [3H]thymidine uptake and immunocytochemical identification of GH-producing cells, we show that 5 nM GRF causes a 20-fold increase in the percentage of somatotrophs labeled with [3H]thymidine. The total number of somatotrophs in GRF-treated cultures was increased by 60%. Somatostatin had no measurable effect on the labeling index by itself, but it partly inhibited the GRF-induced increase in both the labeling index and the total number of cells. Forskolin caused an increase in both the percentage of somatotrophs with a [3H]thymidine-labeled nucleus and the somatotroph number similar to that caused by GRF. GH secretion as well as cellular GH content in the GRF- or forskolin-treated cells increased with culture time over the entire period, whereas secretion and content of GH gradually decreased in control or somatostatin-treated cultures during the entire culture period. These data suggest that GRF and somatostatin regulate the mitotic activity of GH-producing cells and that the effect of GRF is possibly mediated by cyclic AMP.
| Original language | English |
|---|---|
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 83 |
| Issue number | 18 |
| Pages (from-to) | 6854-7 |
| Number of pages | 4 |
| ISSN | 0027-8424 |
| Publication status | Published - Sept 1986 |
Keywords
- Animals
- Cell Division
- Cells, Cultured
- Cyclic AMP
- Growth Hormone
- Growth Hormone-Releasing Hormone
- Male
- Pituitary Gland, Anterior
- Rats
- Rats, Inbred Strains