Luteal enzymes of the luteinizing hormone and beta-adrenergic signal transduction pathways in hypophysectomized rabbits do not require pituitary hormone support
1991
Hunzicker-Dunn, M. | Chen, A. | Jackiw, V. | Gadsby, J.E. | Bill, C.H. II. | LaBarbera, A.R. | Miller, J.B. | Keyes, P.L.
Experiments were conducted to determine whether continuous pituitary hormone support is required for expression of the LH and beta-adrenergic cAMP signal transduction pathways in rabbit CL during pseudopregnancy. Parameters of the LH and catecholamine cAMP signal transduction pathways in CL of estrogen-treated hypophysectomized rabbits were compared to those of pituitary-intact rabbits. Results showed that each of the parameters of the LH and beta-adrenergic cAMP signal transduction pathways was retained in CL taken from estrogen-treated pseudopregnant rabbits that had been hypophysectomized for as long as 13 days at levels not significantly different from those of estrogen-treated pituitary-intact rabbits. These included luteal basal, and LH-, epinephrine-, and fluoride-stimulated adenylyl cyclase activities; total luteal cAMP levels; the number and affinity of cAMP-dependent protein kinase regulatory subunit cAMP binding sites; binding activity of the type I and type II regulatory subunits; and the amount of catalytic subunit protein of cAMP-dependent protein kinase. We conclude that expression of the proteins of the cAMP signal pathway for LH and beta-adrenergic hormones in CL of estrogen-treated rabbits does not require pituitary hormone support.
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