Adenylate cyclase in the corpus luteum of the rhesus monkey, II. sensitivity to nucleotides, gonadotropins, catecholamines, and nonhormonal activators

Kathleen M. Eyster, Richard L. Stouffer

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    18 Scopus citations

    Abstract

    The sensitivity of the adenylate cyclase of the primate corpus luteum to various nucleotides, gonadotropins, catecholamines, and nonhormonal activators was assessed in homogenates of luteal tissue obtained from rhesus monkeys at the midluteal phase of the menstrual cycle. The conversion of [α-32P] ATP to [32P]CAMP was used to monitor adenylate cyclase activity. GTP, the GTP analog 5’-guanylyl-imidodiphosphate, and ITP stimulated adenylate cyclase activity in the presence or absence of exogenous hormone; however CTP, UTP, GMP, and guanosine did not. The gonadotropins, human (h) LH and hCG, stimulated CAMP production in a dose-dependent manner. Maximal stimulation of adenylate cyclase was achieved at 100 nM hLH and hCG, and the activation constant was 20 nM for both hormones. The addition of GTP increased maximal activation of adenylate cyclase by hLH or hCG, but did not alter sensitivity to the hormones. Neither hFSH nor the isolated subunits of hCG stimulated CAMP production. Deglycosylated hCG (native hCG with 70% of the carbohydrate moieties removed) did not stimulate adenylate cyclase activity. However, hLH and intact hCG failed to enhance CAMP production in the presence of an equimolar amount of deglycosylated hCG. The adenylate cyclase of macaque luteal tissue did not respond to the addition of isoproterenol, epinephrine, or phenylephrine. Furthermore, these catecholamines did not affect hCG stimulation of adenylate cyclase. The nonhormonal activators of adenylate cyclase, forskolin and fluoride, stimulated CAMP production in a dose-dependent manner, with maximal stimulation at 100 μM and 10 mM, respectively. Thus, the macaque corpus luteum at the midluteal phase of the menstrual cycle contains a guanine nucleotide-regulated adenylate cyclase which is equally sensitive to the pituitary and placental gonadotropins, hLH and hCG. However, removal of carbohydrate moieties from hCGendows the molecule with gonadotropin-antagonistic properties in the primate. The adenylate cyclase system of the macaque corpus luteum was not responsive to catecholamines; thus, the primate may lack a potential mechanism for control of luteal function that is available to many nonprimate species.

    Original languageEnglish (US)
    Pages (from-to)1552-1558
    Number of pages7
    JournalEndocrinology
    Volume116
    Issue number4
    DOIs
    StatePublished - Apr 1985

    ASJC Scopus subject areas

    • Endocrinology

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