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We have studied the relationship between the prolaction (PRL) release induced by thyroliberin (TRH) and theophylline and the formation and inactivation of adenosine 3', 5'-cyclic monophosphate (cyclic AMP) in cultured rat-pituitary cells (GH3 cells). TRH, which stimulated prolactin release, increased cyclic AMP formation and stimulated transiently both the low- and high-Km cyclic phosphodiesterases. The maximal effect on the phosphodiesterase was observed at 30 mM TRH. The stimulatory effect of TRH on the activity of the cyclic AMP phosphodiesterases was duplicated by incubation of the cells with cyclic AMP (2-10 mM). In washed particulate GH3 cell fractions, TRH increased the adenylyl cyclase activity up to 180%. Treatment of GH3 cells with theophylline stimulated the release of PRL and inhibited cyclic AMP degradation probably leading to the measured increase in cellular concentrations of the nucleotide. The effects of TRH and theophylline on cellular cyclic AMP concentrations and on PRL release were additive. There was a positive correlation between PRL release and cellular cyclic AMP concentration (r = 0.97). The elevations observed in cellular cyclic AMP concentration after TRH treatment are due to increased formation which in turn leads to phosphodiesterase activation. Therefore, cyclic AMP formation appears to be an intermediary step in the stimulus-secretion coupling caused by the tripeptide.
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
September 1987,
Acta endocrinologica,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
January 1979,
Prostaglandins,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
June 1992,
General and comparative endocrinology,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
March 1987,
Molecular and cellular endocrinology,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
October 1980,
Metabolism: clinical and experimental,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
September 1983,
Biochemical pharmacology,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
May 1975,
Journal of immunology (Baltimore, Md. : 1950),
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
March 1988,
International journal of pancreatology : official journal of the International Association of Pancreatology,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
January 1993,
Journal of neural transmission. General section,
K M Gautvik, and
M Kriz, and
T Jahnsen, and
E Haug, and
V Hansson
July 1984,
Thrombosis research,
