The actions of forskolin, cholera toxin and iloprost on casein secretion by lactating doe mammary glands.
The secretagogue effects of prolactin (PRL) and of various agents acting on cAMP levels, forskolin, cholera toxin and iloprost (a stable analogue of prostaglandin I2) have been assessed in lactating doe mammary gland fragments in vitro. Forskolin (10 microM), cholera toxin (1 microgram/ml) and iloprost (10 mM) stimulated milk casein secretion. The effects of forskolin (10 microM) and cholera toxin (1 microgram/ml) were potentiated by PRL (10 micrograms/ml). Conversely, the action of iloprost (10 microM) was not amplified by PRL (10 micrograms/ml). Forskolin (10 microM) and cholera toxin (1 microgram/ml) stimulated the intracellular accumulation of cAMP. Neither PRL nor iloprost, at concentrations which stimulated casein secretion, modified the accumulation of cAMP. These results demonstrate that PRL does not act directly by any increase in intracellular cAMP levels. However, stimulating effects of forskolin and cholera toxin on casein secretion and intracellular cAMP levels suggest that various transduction signals are effective in the mammary cells.
Ollivier-Bousquet
M
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Laboratoire de Biologie Cellulaire et Moléculaire INRA, Jouy-en-Josas, France.
D000818:Animals; D002364:Caseins / Q000378:metabolism*; D002772:Cholera Toxin / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism*; D003670:Deer / Q000378:metabolism; D011464:Epoprostenol / Q000494:pharmacology*; D005260:Female; D016285:Iloprost; D066298:In Vitro Techniques; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000494:pharmacology; D011863:Radioimmunoassay
D002364:Caseins; D005576:Colforsin; D011388:Prolactin; D002772:Cholera Toxin; D011464:Epoprostenol; D000242:Cyclic AMP; D016285:Iloprost