Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors examined the effect of topical application of agents known to increase cyclic nucleotide levels on tear secretion by accessory lacrimal gland tissue in their rabbit model for keratoconjunctivitis sicca (KCS). Tear secretion was studied by changes in tear film osmolarity and tear volume caused by application of the agents relative to application of isotonic buffer solution alone. A decrease in tear film osmolarity or increase in tear volume was interpreted as an increase in tear secretion. Irritative stimulation was distinguished from pharmacologic stimulation by the prior use of topical proparacaine. The following agents significantly decreased tear film osmolarity and increased tear volume: vasoactive intestinal peptide (2 X 10(-8) to 2 X 10(-6) M); three pro-opiomelanocortin fragments alpha-, beta-, and gamma-melanocyte stimulating hormone at 10(-4), 10(-3), and 10(-3) M, respectively; the permeable cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) analogs 8-Br cAMP (0.3-3.0 X 10(-3) M) and 8-Br cGMP (1.0-10.0 X 10(-3) M); and the cyclic nucleotide phosphodiesterase inhibitor 1-isobutyl-3-methyl xanthine (0.3-3.0 X 10(-3) M). Forskolin (2 X 10(-4) M), which activates the catalytic subunits of adenyl cyclase, increased tear volume significantly. Secretin, adrenocorticotropic hormone, and pilocarpine were ineffective. The authors conclude that agents that increase either cAMP or cGMP levels pharmacologically stimulated tear secretion when applied topically to rabbit eyes with surgically induced KCS.
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PMID:Stimulation of tear secretion by topical agents that increase cyclic nucleotide levels. 236 69

Plasma membrane sacs of isolated rat fat cells (ghots) possess an adenyl cyclase system, which is activated by lipolytic hormones of disparate molecular structure, including adrenocorticotropin (ACTH), glucagon, and epinephrine. Previous studies indicated that distinctive selectivity units for individual hormones are coupled to the same unit of adenyl cyclase in the fat cell membrane. The present study has shown that ghost cyclase from adrenalectomized and hypophysectomized rats exhibits a striking reduction in response to ACTH, the stimulatory effects of epinephrine, glucagon, or fluoride being unchanged. Pretreatment of adrenalectomized, hypophysectomized, sham operated, or intact rats with the synthetic glucocorticoid, dexamethasone, selectively increased the ACTH response in ghost cyclase preparations. Cortisol, like dexamethasone, increased the ACTH response in ghosts from adrenalectomized rats; 11-deoxycorticosterone was ineffective. The dexamethasone effect to enhance the ACTH response is blocked by actinomycin D or cycloheximide. The present results show that stimulation of rat fat cell adenyl cyclase by ACTH involves a distinctive molecular entity, which can be clearly differentiated from adenyl cyclase in the membrane as well as from the selectivity sites for epinephrine and glucagon. The data indicate that the biosynthesis of the component required for ACTH stimulation of ghost cyclase-either an ACTH selectivity unit or specific coupling factor-is induced by glucocorticoids at the level of gene regulation.
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PMID:Glucocorticoid regulation of ACTH sensitivity of adenyl cyclase in rat fat cell membranes. 431 84

Properties of adenyl cyclase of normal adrenals and of a corticosterone-producing adrenal cancer of the rat have been compared. Enzyme activity was found in all particulate fractions of both tissues. The cyclase of the tumor as well as of the adrenals was stimulated by adrenocorticotropic hormone (ACTH) over similar concentration ranges. Unexpectedly, the tumor enzyme was also stimulated by epinephrine, norepinephrine, and thyroid-stimulating hormone (TSH). These hormones produced a dose-related effect over a concentration span that was comparable with that for ACTH. The tumor cyclase was not responsive to angiotensin Il, vasopressin, glucagon, insulin, growth hormone, parathyroid hormone, and thyrocalcitonin. ACTH was the only hormonal preparation that stimulated normal adrenal cyclase. These findings are compatible either with the possibility that the adenyl cyclase receptor of the tumor has undergone structural alteration with a consequent loss of specificity for ACTH or with the possibility that the tumor possesses several cyclase regulatory receptors.
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PMID:Abnormal hormone responses of an adrenocortical cancer adenyl cyclase. 432 11

A heat-labile, Pronase-sensitive factor has been partially purified from cell-free culture filtrates of enterotoxigenic Escherichia coli. The partially purified factor contains both protein and carbohydrate moieties and appears to be E. coli enterotoxin (ECT). ECT binds to cultured adrenal tumor cells rapidly and irreversibly leads to adenosine 3', 5'-cyclic monophosphate formation and steroidogenesis after a 60-min lag phase. Further studies indicate that it interacts with the cholera toxin receptor site on adrenal cells rather than the adrenocorticotropin receptor to activate adenyl cyclase. Mixed gangliosides block stimulation of steroidogenesis in response to both E. coli and cholera enterotoxin. In contrast to adrenocorticotropin, ECT has no additive effect on cholera toxin-induced steroidogenesis. The protein moiety of ECT is similar to cholera enterotoxin because horse serum anticholeragenoid prevented stimulation of steroidogenesis by either enterotoxin. Cultured adrenal cells provide a quantitative assay system that has facilitated the purification and characterization of E. coli enterotoxin.
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PMID:Escherichia coli enterotoxin-induced steroidogenesis in cultured adrenal tumor cells. 436 19

A spontaneously occurring rat adrenocortical carcinoma which produces corticosterone was maintained by transplantation. The carcinoma appeared to utilize corticosterone biosynthetic steps similar to those of the normal adrenal, but the tumor produced only about 1-10% as much corticosterone per unit tissue weight as nontumorous adrenal glands. The tumor demonstrated little or no increase in corticosterone production in response to adrenocorticotropic hormone (ACTH) either in vivo or in vitro. In normal adrenals, ACTH increases the activity of adenyl cyclase which catalyzes the conversion of adenosine triphosphate (ATP) to adenosine-3',5'-monophosphate (cyclic AMP), the latter then serving as an intracellular regulator of steroidogenesis. ACTH failed to increase cyclic AMP levels in the tumor in vivo or in slices in vitro, conditions under which there were 50- and 20-fold increases in nontumorous adrenals. However, in homogenates fortified with exogenous ATP, adenyl cyclase activity was comparable in the tumor and adrenals, and cyclic AMP formation was increased 3-fold by ACTH in each. As measured in homogenates, the tumor did not possess a greater ability to destroy cyclic AMP than did normal adrenals. Although ATP levels in the carcinoma were found to be considerably lower than those in normal adrenals, it was not clear that this finding can explain the inability of ACTH to increase cyclic AMP levels in intact tumor cells. While the failure to normally influence cyclic AMP levels in the carcinoma cells could be an important factor in the lack of a steroid response to ACTH, several lines of evidence suggest that the tumor possesses one or more additional abnormalities in the regulation of steroidogenesis. First, in the absence of ACTH stimulation, the tissue concentrations of cyclic AMP were comparable in the tumor and in nontumorous adrenals, but these cyclic AMP levels were associated with a lower level of steroidogenesis in the tumor. Second, tumor slices failed to increase corticosterone production when incubated with cyclic AMP, in contrast to 5-fold increases observed with nontumorous adrenals.
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PMID:Abnormal regulation of adenosine 3',5'-monophosphate and corticosterone formation in an adrenocortical carcinoma. 439 Apr 12

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

In previous studies cadmium chloride (CdCl2) nonlethally inhibited Y-1 mouse adrenal tumor cell 20-dihydroxyprogesterone (20DHP) secretion, affecting unstimulated and stimulated steroidogenic pathway sites differently. In addition, dibutyryl cAMP-stimulated 20DHP secretion was unaffected by CdCl2, while the site of the unstimulated effect was indirectly shown to involve steps between endogenous cholesterol utilization and 20-hydroxycholesterol association with mitochondrial cytochrome P450 side-chain cleavage enzyme. In the present study we determined CdCl2 effects on plasma membrane sites preceding pre-dbcAMP-stimulation of 20DHP secretion. Y-1 cells were incubated 0.5 h in medium with or without cadmium (using the concentration that inhibited adrenocorticotropin- (ACTH)-stimulated steroid secretion by 50%) together with exogenously added maximally stimulating concentrations of ACTH, cholera toxin, forskolin, or adenosine triphosphate. Cholera toxin, forskolin and ATP bypass specific plasma membrane sites involved in the synthesis of intracellular cAMP and activate the steroid hormone biosynthetic pathway. Cadmium effects on ACTH-stimulated endogenous cAMP secretion were also examined. CdCl2 significantly reduced Y-1 cell 20DHP secretion following exposure to ACTH, cholera toxin, forskolin, and ATP; it also significantly decreased endogenous cAMP secretion into culture medium. These data may be interpreted to suggest that CdCl2 altered Y-1 cell regulation of adenyl cyclase activity, which reduced cAMP-activated cholesterol uptake by mitochondria as a consequence.
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PMID:Modulation of adrenal cell functions by cadmium salts: 3. Sites affected by CdCl2 during stimulated steroid synthesis. 807 21

To examine the possibility of luteolin as a whitening agent, we measured antioxidant activity using DPPH assay, NBT/XO assay and intracellular ROS scavengning assay and depigmenting activity using tyrosinase assay, alpha-MSH-induced melanin production in B-16 cells. Luteolin showed dose-dependent anti-oxidant activity in DPPH, NBT/XO and intracellular ROS assay. Also, luteolin directly inhibited xanthine oxidase activity in a dose-dependent manner. Although luteolin did not directly inhibit tyrosinase activity, it dose-dependently inhibited both tyrosinase activity and melanin production in B16 melanoma cells stimulated by 1 microM alpha-MSH. Luteolin dose-dependently inhibited cAMP levels in B16 melanoma cells stimulated by 1 microM alpha-MSH and 1 microM forskolin, which suggest that luteolin directly inhibits adenyl cyclase in B16 melanoma cells. Therefore, these results suggest that whitening activity of luteolin may be due to the inhibition of adenyl cyclase involved in the signal pathway of alpha-MSH in B16 melanoma cells.
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PMID:Whitening activity of luteolin related to the inhibition of cAMP pathway in alpha-MSH-stimulated B16 melanoma cells. 1880 60