Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A near-maximal dose (20 ng/ml) of synthetic luteinizing hormone(LH)-releasing hormone/follicle-stimulating hormone(FSH)-releasing hormone added to incubated anterior pituitary tissue of male rats leads to concomitant increases of intracellular concentrations of adenosine 3':5'-monophosphate and of release of both LH and FSH. The stimulatory effect of LH-releasing hormone/FSH-releasing hormone is observed after a lag period of about 90 min and is progressive at later time intervals; a 3-fold stimulation of cAMP accumulation over control is seen after 210 min of incubation. Half-maximal stimulation of cAMP accumulation is observed between 0.1 and 1.0 ng/ml (0.1-1 nM) of LH-releasing hormone/FSH-releasing hormone. In the presence of 10 mM theophylline, the stimulatory effect of LH-releasing hormone/FSH-releasing hormone on cAMP accumulation is similar to that observed in the absence of the inhibitor of cyclic nucleotide phosphodiesterase, indicating that the releasing hormone exerts its effect by specific activation of adenylate cyclase in LH- and FSH-secreting cells rather than by inhibition of cyclic nucleotide phosphodiesterase. Since the release of growth hormone, thyrotropin, prolactin, and adrenocorticotropic hormone is not affected by LH-releasing hormone/FSH-releasing hormone, and since cAMP stimulates the release of all six adenohypophyseal hormones. the observed changes of cAMP concentrations indicate specific stimulation of adenylate cyclase activity in LH-and FSH-secreting cells of the adenohypophysis.
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PMID:Stimulation of adenosine 3':5'-cyclic monophosphate accumulation in anterior pituitary gland in vitro by synthetic luteinizing hormone-releasing hormone. 434 5

We have shown that two unrelated prostaglandin antagonists block both thyrotropin (TSH) and prostaglandins E (PGE(1), PGE(2)) stimulation of thyroidal adenyl cyclase activation and cyclic 3',5'-adenosine monophosphate (cAMP) formation, suggesting that prostaglandins play an important role in regulating thyroid function. To further explore this postulate, we measured prostaglandin content by radioimmunoassay in homogeneous bovine thyroid cell preparations in the presence and absence of TSH. Antibodies to albumin-conjugated PGE(1) and PGF(2alpha) showed specificity for prostaglandins E and F, respectively, but reacted, albeit far less effectively, with heterologous prostaglandins. A double antibody system was used to separate free from antibody-bound PGE(1)-(3)H and PGF(2alpha)-(3)H. Thyroid cells were extracted with ethanol/ethyl acetate and the various prostaglandins separated on silicic acid columns. Recoveries of added PGE(1)-(3)H and PGF(2alpha)-(3)H through the extraction and separation procedures ranged from 50-80%. The sensitivity of the method was 10-50 pg. Basal thyroid cell content of PGE(1) and PGF(2alpha) "equivalents" varied between cell preparations (range = 2-6 ng/0.2 ml cell suspension) but, in each instance, remained constant during 5-30-min incubations at 37 degrees C. TSH, 10-100 mU/ml, increased the levels of cell PGE(1) and PGF(2alpha) "equivalents" 30-80% above basal during 5-15-min incubations. The stimulatory effect was specific for TSH, no increase in PGE(1) or PGF(2alpha) "equivalent" levels being seen with luteinizing hormone (LH), human growth hormone (HGH), adrenocorticotropic hormone (ACTH), or glucagon. These data support the thesis that prostaglandins may mediate TSH effects on thyroid.
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PMID:Thyrotropin increases prostaglandin levels in isolated thyroid cells. 462 70

The stimulatory effect of maximal concentrations of synthetic human pancreatic growth hormone (GH)-releasing factor (GRF)(1-40)NH on cyclic AMP accumulation in rat anterior pituitary cells in culture is 4.5-fold increased following a 48-h preincubation with the potent glucocorticoid dexamethasone while the sensitivity of GRF action is increased by approximately 4-fold. Dexamethasone pretreatment, on the other hand, has no effect on basal cyclic AMP levels but approximately doubles both basal and GRF-induced GH release. The present data suggest that the potent stimulatory effect of glucocorticoids on GH secretion is exerted on the adenylate cyclase system at a step preceding cyclic AMP formation.
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PMID:Dexamethasone is a potent stimulator of growth hormone-releasing factor-induced cyclic AMP accumulation in the adenohypophysis. 608 69

1. Interpretation of neuroendocrine studies in schizophrenia requires consideration of (a) the large number of variables that affect drug-induced endocrine responses (b) the effect of prior neuroleptic therapy (c) heterogeneity of schizophrenia (d) heterogeneity of receptors (e) uniqueness of the hypothalamic-pituitary axis (f) selectivity and pharmacokinetics of administered drugs. 2. Apomorphine increases growth hormone secretion by an effect on dopamine receptors that are not linked to adenylate cyclase and which are located outside the blood brain barrier. 3. Hypothalamic-pituitary histaminergic H2 and alpha-adrenergic function are unchanged in chronic schizophrenia. 4. Schizophrenic symptoms persist despite complete blockade of dopamine receptors modulating prolactin secretion. 5. Studies on dopamine receptors modulating prolactin secretion are unlikely to shed light on the pathophysiology of schizophrenia. 6. Screening for drugs which block apomorphine-induced growth hormone secretion but do not increase prolactin may provide a way of detecting anti-schizophrenic drugs which are devoid of side effects associated with hyperprolactinemia and which do not induce parkinsonism or tardive dyskinesia.
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PMID:Drug-induced growth hormone and prolactin responses in schizophrenia research. 613 95

Bioassay of hormones has a small but important role in defining the physiologic status of selected patients in whom immunoassay results do not correlate with clinical signs and symptoms. This article reviews three sensitive bioassays for hormones, which are based on 1) stimulation of adenylate cyclase in membrane preparations, 2) cytochemical changes in fresh tissue segments or sections, and 3) stimulation of cell replication in the Nb2 lymphoma cell culture. The adenylate cyclase assay using kidney membranes can measure parathyroid hormone (PTH), whereas assays using thyroid membranes can measure both thyrotropin (TSH) and thyroid-stimulating immunoglobulins (TSI). The cytochemical assay methods can measure numerous hormones, but the two most promising assays for clinical use are the PTH assay using guinea pig distal convoluted renal tubules and TSH/TSI assay using thyroid follicles. The Nb2 lactogenic assay is sensitive to biologic concentrations of growth hormone, prolactin, and human placental lactogen.
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PMID:Bioassay of hormones. 614 90

The interaction of growth hormone-releasing factor (GRF) and somatostatin (SRIF) on adenylate cyclase activity and growth hormone release was investigated in pituitary homogenates and 2-day cultured rat anterior pituitary cells. GRF stimulated growth hormone release by about 3-fold (ED50 1.6 X 10(-12) M) and caused a rapid 15-fold increase in cyclic AMP production (ED50 6.0 X 10(-12) M). The increase in cyclic AMP was due to direct stimulation of adenylate cyclase by GRF, which caused a 4-fold increase in the activity of the enzyme measured in anterior pituitary homogenates. GRF-induced cyclic AMP formation and GRF-stimulated adenylate cyclase activity were maximally inhibited to the extent of about 50% by 10(-8) M somatostatin. In contrast, GRF-stimulated growth hormone release was completely inhibited by somatostatin (ID50 3.2 X 10(-11) M), suggesting a second site of action of somatostatin. These studies demonstrate that GRF stimulates growth hormone release via activation of adenylate cyclase and a rise in intracellular cyclic AMP. In addition, these findings indicate that the inhibitory action of somatostatin on growth hormone release is exerted at two levels, one at the level of adenylate cyclase affecting the production of cyclic AMP, and the other beyond the formation of the nucleotide, at a site which modulates the release of growth hormone from the cell.
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PMID:Actions of growth hormone-releasing factor and somatostatin on adenylate cyclase and growth hormone release in rat anterior pituitary. 614 68

The pathophysiological role of endorphins in septic shock was studied in a porcine model. Septic shock was induced by the intravenous infusion of live Escherichia coli. Naloxone hydrochloride, an opiate receptor blocker, given during profound septic shock, increased blood concentrations of glucagon and cyclic adenosine monophosphate (cAMP), while BP and cardiac output increased transiently. Heart rate and hepatic glycogen value decreased, but insulin and cortisol levels remained unchanged. In contrast, exogenous morphine injection produced further reduction of BP, increased pulmonary wedge pressure, and increased substance P, while growth hormone level and cardiac output remained unchanged. Neither hormonal nor hemodynamic changes were noted in saline controls. Thus, the endogenous opiates appear partly responsible for the hemodynamic derangements during septic shock, and naloxone is able to reverse such depression, even though the effects are transient and relatively minor when naloxone is given late in the course of septic shock. Endogenous opiates also affect the hormonal homeostasis in shock, and there are indications that this may be mediated by the adenylate cyclase-cAMP system.
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PMID:Endorphins in septic shock: hemodynamic and endocrine effects of an opiate receptor antagonist and agonist. 628 53

Pertussis toxin, cholera toxin and forskolin, all of which can increase adenylate cyclase activity, stimulated luteinizing hormone LH release from cultured rat anterior pituitary cells. Although cellular cyclic AMP and growth hormone were increased rapidly by cholera toxin and forskolin, enhanced LH release occurred significantly later with no change in total radioimmunoassayable LH (i.e., released plus stored). These data suggest that changes in cyclic AMP levels may regulate the tonic availability of releasable LH in the gonadotroph.
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PMID:Luteinizing hormone secretion is enhanced by pertussis toxin, cholera toxin, and forskolin. Evidence for the involvement of the cyclic AMP-generating system. 631 Apr 32

The chemical tools that could be used to examine the function of histamine in the brain are considered together with the evidence linking histamine specifically with the hypothalamus. The distribution of histamine and the enzymes responsible for its synthesis and metabolism is consistent with there being both mast cells and histaminergic nerve terminals within the hypothalamus. Iontophoresis, mepyramine binding and histamine-stimulated adenylate cyclase studies suggest that both histamine H1- and H2- receptors are present in the hypothalamus. In addition, intracerebroventricularly injected histamine receptor agonists and antagonists affect many functions associated with the hypothalamus such as cardiovascular control, food intake, body temperature control, and pituitary hormones whose release is mediated via the hypothalamus, such as corticotropin, growth hormone, thyroid stimulating hormone, prolactin, gonadotropins and vasopressin. However, only in the case of thyroliberin release, prolactin release, body fluid control and blood pressure control is there evidence yet that such effects are mediated via histamine receptors actually in the hypothalamus. The effects of enzyme inhibitors suggest endogenous histamine may be involved in the physiological control of thyroid stimulating hormone, growth hormone and blood pressure, and the effects of receptor antagonists support a role for endogenous histamine in prolactin control. Otherwise, there is little evidence for a physiological role for endogenous, as against exogenous, histamine whether it be from histaminergic terminals or mast cells. In addition, few studies have tried to distinguish possible effects on presynaptic receptors, postsynaptic receptors, hypothalamic blood vessels or the hypophyseal portal blood vessels. It is concluded that although there is good evidence now linking histamine and the hypothalamus more specific studies are required, for instance using microinjection or in vitro techniques and the more specific chemical tools now available, to enable a clearer understanding of the physiological role of histamine in the hypothalamus.
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PMID:Histamine and the hypothalamus. 631 74

Addition of corticotropin-releasing factor (CRF) to membranes from two ACTH-secreting pituitary tumors strikingly increased in a dose-dependent fashion adenylate cyclase (AC) activity. Significant stimulation was already apparent at 10(-9)M CRF. Stimulation of AC activity by CRF in membranes from non-tumoral tissue adjacent to tumoral corticotrophs was considerably lower, and was lacking in membranes from a growth hormone secreting tumor. These data correlated well with in vivo pre-surgery and post-surgery ACTH responsiveness to CRF of the tumor bearing patients. Basal AC activity was higher in pituitary adenomas than in non-tumoral adjacent tissue. It is concluded that 1) a CRF-sensitive AC exists in ACTH-secreting tumor cells and, 2) increased sensitivity to CRF, as evidenced by greater stimulation of AC activity, may be responsible for the increased ACTH output of tumoral corticotrophs.
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PMID:Corticotropin releasing factor stimulates cAMP formation in pituitary corticotropic tumor cells. 631 41


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