Growth hormone and prolactin gene expression and release in the pituitary of rainbow trout in serum-free culture.
The trout pituitary continuously released a large amount of GH for over a week in serum-free culture, but PRL secretion declined by day 2 in culture. The total amount of GH released during the 8 days exceeded the initial content. The pituitary content of PRL remained unchanged after 8 days of culture. The number of weakly stained GH-immunoreactive (ir) cells was increased by day 4 in culture. The GH mRNA levels in individual cells as revealed by in situ hybridization were maintained at around the same level throughout culture. In contrast, the stainability of PRL-ir cells remained unchanged during culture, although the levels of PRL mRNA decreased by day 8. Electron microscopic immunocytochemistry showed a decrease in the numbers of secretory granules and dilation of rough endoplasmic reticulum in GH-ir cells. GH synthesis, measured by incorporated [3H]leucine after GH immunoprecipitation, was elevated 120% on day 8 over day 0. The dominant control of GH and PRL secretion in rainbow trout seems to be the converse of those seen in mammals; inhibition for GH and stimulation for PRL.
Yada
T
T
Ocean Research Institute, University of Tokyo, Japan.
Urano
A
A
Hirano
T
T
D000818:Animals; D003470:Culture Media; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D015870:Gene Expression; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008854:Microscopy, Electron; D009693:Nucleic Acid Hybridization; D009924:Organ Culture Techniques / Q000379:methods; D010902:Pituitary Gland / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D011388:Prolactin / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D014337:Trout
D003470:Culture Media; D012333:RNA, Messenger; D011388:Prolactin; D013006:Growth Hormone; D007930:Leucine