UMLS:C0011570 - FACTA Search

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Query: UMLS:C0011570 (depression)
172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The potassium stimulated release of [3H]norepinephrine ([3H]NE) from terminal fields of locus coeruleus projections can be inhibited in a dose-dependent manner by mu and kappa selective opioids. Chronic exposure to morphine for six days decreases the maximum achievable depression by the mu selective agonist Tyr-D-Ala2-Gly-Me(Phe)-Gly-ol (DAGO), but has no effect on the degree of inhibition produced by the kappa selective opioid U50,488H.
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PMID:Effects of prior exposure to morphine on the opioid inhibition of the stimulated release of [3H]norepinephrine from guinea pig cortex slices. 282 6

The effects of selective opioid receptor agonists and antagonists on neural discharge recorded from carotid body arterial chemoreceptors in vivo were studied in anaesthetized cats. Mean ID50 values were determined for each agonist and used to assess chemodepressant potency on intracarotid (i.c.) injection in animals artificially ventilated with air. [Met]enkephalin, [Leu]enkephalin, [D-Ala2, D-Leu5]enkephalin and [D-Pen2, D-Pen5]enkephalin were more potent chemodepressants than [D-Ala2, Me-Phe4, Gly-ol5]enkephalin, dynorphin (1-8) or ethylketocyclazocine; morphiceptin (mu-agonist) was inactive. The rank order of potency was compatible with the involvement of delta-opioid receptors in opioid-induced depression of chemosensory discharge. ICI 154129, a delta-opioid receptor antagonist, was used in fairly high doses and caused reversible dose-related antagonism of chemodepression induced by [Met]enkephalin. It also antagonized depression caused by single doses of [Leu]enkephalin, [D-Ala2, D-Leu5]enkephalin, [D-Ala2, Me-Phe4, Gly-ol5]enkephalin or dynorphin (1-8). ICI 174864, a more potent and selective delta-opioid receptor antagonist, also antagonized chemodepression induced by [Met]enkephalin or by the selective delta-receptor agonist [D-Pen2, D-Pen5]enkephalin. Comparison of background or 'spontaneous' chemosensory discharge during the 30 min periods immediately before and after injecting ICI 174864 (0.1-0.2 mg kg-1 i.c.) showed a significant increase in discharge in one experiment, but in four others discharge was either unaffected or decreased after the antagonist, which argues against a toxic depression of chemosensors by endogenous opioids under resting conditions in our preparation. Sensitivity of the carotid chemoreceptors to hypoxia (ventilating with 10% O2) was increased significantly after ICI 174864, which could be taken as evidence that endogenous opioids depress chemosensitivity during hypoxia. In contrast, responsiveness to hypercapnia was reduced after the antagonist, implying that endogenous opioids may potentiate chemoreceptor sensitivity during hypercapnia. The results obtained using 'selective' agonists and antagonists provide evidence that depression of chemosensory discharge caused by injected opioids involves a delta type of opioid receptor within the cat carotid body. Endogenous opioids may modulate arterial chemoreceptor sensitivity to physiological stimuli such as hypoxia and hypercapnia.
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PMID:Characterization of opioid receptors in the cat carotid body involved in chemosensory depression in vivo. 287 62

We have examined the sites phosphorylated on acetyl-CoA carboxylase by three protein kinases which have been shown to inactivate the enzyme, i.e. cyclic-AMP-dependent protein kinase, acetyl-CoA carboxylase kinase-2 (ACK2, purified from rat mammary gland) and the AMP-activated protein kinase (formerly called acetyl-CoA carboxylase kinase-3, purified from rat liver). Each protein kinase phosphorylates two out of three sites (termed 1-3) which have been established by amino acid sequencing. The two sites phosphorylated by each kinase can be recovered on separate peptides, TC1 and TC2, derived by combined digestion of the native enzyme by trypsin and chymotrypsin: TC1 = Ser-2Ser(P)-Met-3Ser(P)-Gly-Leu; TC2 = Arg-Met-1Ser(P)-Phe- Cyclic-AMP-dependent protein kinase phosphorylates sites 1 and 2 exclusively, whereas the AMP-activated protein kinase phosphorylates sites 1 and 3, plus at least one other minor site. ACK2 phosphorylates site 1 and, more slowly, an unidentified site(s) within TC1. We have also established the structures of the single major phosphopeptides (T1 and C1 respectively) which are recovered by HPLC after acetyl-CoA carboxylase phosphorylated by cyclic-AMP-dependent protein kinase is digested with trypsin or chymotrypsin alone. T1 is related to TC1, and has the structure: Ser-Ser(P)-Met-Ser-Gly-Leu-His-Leu-Val-Lys. C1 is identical with TC2. We have carried out studies on the correlation of the activity of acetyl-CoA carboxylase with the occupancy of sites 1, 2 and 3 during phosphorylation by each of the three protein kinases. The results suggest that phosphorylation of site 3 is primarily responsible for the large decrease in Vmax produced by the AMP-activated protein kinase, while phosphorylation of site 1 may be primarily responsible for the increase in A0.5 for citrate and more modest depression of Vmax produced by cyclic-AMP-dependent protein kinase and ACK2. Our results emphasize that amino acid sequence information is essential in the unequivocal interpretation of data from phosphopeptide mapping experiments and allow a more complete interpretation of previous data on phosphorylation of acetyl-CoA carboxylase in intact cells. They also open the way to experiments which could establish the physiological roles of these protein kinases in the control of fatty acid synthesis.
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PMID:Identification by amino acid sequencing of three major regulatory phosphorylation sites on rat acetyl-CoA carboxylase. 290 Jan 38

Possible protective effects of the agonist [D-Trp6]LH-RH (analog of luteinizing hormone-releasing hormone in which Gly-6 is replaced by D-tryptophan) and antagonist N-Ac-[D-Phe(pCI)1,2,D-Trp3,D-Arg6,D-Ala10]LH-RH against testicular damage caused by x-radiation were investigated in rats. Three months after being subjected to x-irradiation of the testes with 415 or 622 rads, control rats showed marked reduction in the weights of the testes and elevated levels of LH and follicle-stimulating hormone (FSH), indicating tubular damage. Histological studies demonstrated that, in testes of rats given 415 rads, most seminiferous tubules had only Sertoli cells and no germinal cells, and, in the group given 622 rads, the depression of spermatogenesis was even more marked. Rats pretreated for 50 days with LH-RH antagonist (1000 micrograms/kg of body weight per day) showed a complete recovery of testicular weights and spermatogenesis 3 months after 415 rads and showed partial recovery after 622 rads, and LH and FSH levels returned to normal in both of these groups. Thus, pretreatment of rats with LH-RH antagonist, by reversibly inhibiting gonadal function, protected the germinal cells of the testes against damaging effects of x-rays. Three experiments were also carried out in which the rats were pretreated for 1-2 months with long-acting microcapsules of the agonist [D-Trp6]LH-RH, liberating 25 micrograms of the agonist per day. Some rats were then subjected to gonadal irradiation with 415 or 622 rads and allowed a recovery period of 2-4 months. In spite of pretreatment with [D-Trp6]LH-RH, testicular weights were significantly lower and LH or FSH levels were elevated in the irradiated groups as compared with nonirradiated controls. The recovery of spermatogenesis was incomplete, and there was a decrease in the number of germinal cells after 415 rads and especially after 622 rads. On the basis of testicular weights, histology, and gonadotropin levels, it could be concluded that the agonist [D-Trp6]LH-RH did not protect the rat testes exposed to 622 rads and, at most, only partially protected against 415 rads. These results suggest that pretreatment with LH-RH antagonists and possibly agonists, might decrease the testicular damage caused by radiation and accelerate the recovery of reproductive functions.
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PMID:Protective effects of analogs of luteinizing hormone-releasing hormone against x-radiation-induced testicular damage in rats. 294 28

Intracellular recordings were made from neurons of the rat locus coeruleus contained within a brain slice maintained in vitro. When applied to the slice in known concentrations the selective kappa opioid receptor agonist trans-(+)-3,4-dichloro-N-methyl-[2-(1-pyrrolidinyl)cyclohexyl] benzeneacetamide methane sulphonate (U50488) (0.01-1 microM) produced a concentration-dependent depression of the excitatory post-synaptic potential evoked by electrical stimulation of afferent inputs to the locus coeruleus. This effect was antagonized by naloxone with an apparent dissociation equilibrium constant (Kd) of 28 nM. U50488 did not completely abolish the EPSP. Over the same concentration range U50488 had no effect on the resting membrane potential, input resistance or action potential waveform of locus coeruleus neurons, nor did U50488 depress the depolarization produced by local application of L-glutamic acid. The mu opioid receptor agonists [D-Ala2, NMe Phe4, Gly-ol5] enkephalin (0.003-1 microM) and [D-Ala2, NMe Phe4, Met(O)5] enkephalinol (0.003-1 microM) caused a membrane hyperpolarization concomitant with a fall in neuronal input resistance. These effects were concentration-dependent and antagonized by naloxone with an apparent Kd of 1.5 nM. Mu agonists also caused a depression of the tetrodotoxin resistant action potential. An in vitro autoradiographic study of [3H]bremazocine binding within the locus coeruleus revealed that, although the majority of binding appears to be to mu sites, a significant proportion was displaceable by unlabelled U50488 and thus represented kappa binding sites. The possibility that kappa opioid receptors may be located pre-synaptically within the locus coeruleus, and that activation of these receptors depresses excitatory synaptic input, is discussed.
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PMID:Kappa opioid receptor activation depresses excitatory synaptic input to rat locus coeruleus neurons in vitro. 303 41

1. Antitussive, antinociceptive and respiratory depressant effects of codeine, morphine and H.Tyr.D-Arg.Gly.Phe(4-NO2) Pro.NH2 (compound BW443C) were investigated in unanaesthetized guinea-pigs. Antagonism of the antitussive and antinociceptive effects was investigated by the use of nalorphine and N-methylnalorphine. Naloxone was used to antagonize respiratory depression. 2. Antitussive ED50s (with 95% confidence limits) for inhibition of cough induced by citric acid vapour were for codeine, morphine and BW443C respectively, 9.1(5.8-15), 1.3(0.7-2.4) and 1.2(0.6-2.6) mg kg-1 s.c. and 8.7(4.2-12), 1.6(1.2-1.9) and 0.67(0.002-3.3) mg kg-1, i.v. The antitussive effects of subcutaneous codeine (25 mg kg-1) morphine (8.1 mg kg-1) and BW443C (2.5 mg kg-1) were significantly antagonized by subcutaneous nalorphine (3.0 mg kg-1) and N-methylnalorphine (3.0 mg kg-1). 3. In the multiple toe-pinch test, the antinociceptive ED50s (with 95% confidence limits) of codeine and morphine were 18(16-22) and 2.3(0.4-4.3) mg kg-1, s.c., respectively. Compound BW443C was ineffective in doses of 2.5 and 10 mg kg-1 s.c., a result consistent with its lacking penetration into the CNS. Subcutaneous nalorphine (3.0 mg kg-1) antagonized the antinociceptive action of codeine (25 mg kg-1) and morphine (8.1 mg kg-1). In contrast, N-methylnalorphine (3.0 mg kg-1) had no significant effect on the antinociceptive action of codeine and morphine, suggesting lack of penetration of the CNS by N-methylnalorphine. 4. At doses near to the i.v. ED50 values for the antitussive activity, morphine (1.5mg kg- ', i.v.) and codeine (10mg kg-', i.v.) caused small but significant depressions of ventilation (7.0 +/- 2.3% and 16.5 +/- 8.4% respectively). Higher doses of morphine (10, 30 and 60mg kg- ', i.v.) caused further doserelated depression of ventilation (9.6 +/- 5.3%, 22.4 +/- 6.2% and 36.2 +/- 9.6% respectively) whereas codeine (30 and 60mg kg-' i.v.) caused stimulation of ventilation which was marked (191.3 +/- 43.9%) at 60 mg kg-'. 5. Compound BW443C in doses of 1 or 10mgkg-',i.v. (approximately equal to, and 10 times the EDo for antitussive activity) did not cause significant depression of ventilation. Only at higher doses of 30 and 60mg kg-', i.v. was there a significant decrease in minute volume (13.1 +/- 6.8% and 15.9 +/- 1.89% respectively). The depression of ventilation caused by either BW443C (60mg kg-', i.v.) or morphine (60mg kg-', i.v.) was prevented by pretreatment with naloxone (3mg kg-', i.v.) administered 15 min before morphine or BW443C. 6. These results in the guinea-pig support the hypothesis that the antitussive action of the opiates codeine and morphine and the opioid pentapeptide BW443C do not require penetration of these drugs into the CNS.
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PMID:Effects of codeine, morphine and a novel opioid pentapeptide BW443C, on cough, nociception and ventilation in the unanaesthetized guinea-pig. 334 36

Organotypic cultures of fetal mouse spinal cord-ganglion explants (2-4 weeks in vitro) contain forskolin-stimulated adenylate cyclase (AC) activity that is inhibited by levorphanol and other opioid agonists in a dose-dependent manner. Inhibition by levorphanol no longer occurs if sodium is omitted from the incubation and the levorphanol inhibition is blocked by the opioid antagonist, naloxone. These findings together with the ineffectiveness of dextrorphan indicate that the opioid inhibition of forskolin-stimulated AC is receptor mediated. Both the delta- and kappa-receptor subtypes appear to be involved since the selective delta-opioid agonist, [D-Pen2, D-Pen5]enkephalin, and the selective kappa-opioid agonist, t-3,4-dichloro-N-methyl-N[2-(1-pyrrolidinyl)cyclohexyl]-benzene acetamide (U-50,488H) are both effective at nanomolar concentrations. In contrast, the selective mu-opioid agonist, Tyr-D-Ala-Gly-N-MePhe-Gly-ol, has no significant effect even at micromolar concentrations. Both cord and ganglion components of the explants contain opioid-sensitive AC. Forskolin-stimulated AC of the explants is also inhibited by serotonin and carbachol. The serotonin effect appears to be mediated by 5-HT1A receptors, based on relative agonist and antagonist selectivity. Chronic exposure of cultures to morphine results in enhanced basal and forskolin-stimulated AC as well as attenuation of opioid-inhibition of AC assayed in the presence of forskolin; treatment of explants with pertussis toxin causes similar changes in the AC system. The inhibitory effect of serotonin is also attenuated by the pertussis toxin treatment. Basal AC activity of the explants (assayed without forskolin present) is stimulated to a small but significant extent by opioids and by serotonin. The opioid stimulatory effect is markedly enhanced following either morphine or pertussis toxin treatment of the explants. The attenuation of opioid- and serotonin-inhibition of AC produced by chronic exposure to pertussis toxin and the attenuation of opioid inhibition produced by exposure to morphine are consonant with the attenuation of opioid and monoaminergic depression of sensory evoked dorsal horn network responses after similar chronic treatments. It is proposed that the inhibitory effects of opioids and serotonin on these neurons are mediated by receptors that are negatively coupled via a pertussis toxin sensitive Gi protein to AC. Furthermore, alterations of AC with chronic morphine treatment may be involved in the development of physiologic tolerance to opioids.
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PMID:Modulation of adenylate cyclase activity of mouse spinal cord-ganglion explants by opioids, serotonin and pertussis toxin. 337 Apr 65

Intracellular recordings were made from neurones in the rat locus coeruleus in a brain slice maintained in vitro. Phencyclidine and related psychotomimetic drugs, applied in known concentrations in the fluid bathing the slice, depressed responses to N-methyl-D-aspartic acid noradrenaline (in the presence of the uptake inhibitor desmethylimipramine) and [D-Ala2,MePhe4,Gly-ol5]enkephalin and also prolonged the action potential. The sensitivities of these responses to depression by phencyclidine was N-methyl-D-aspartic acid (IC50 0.4 microM) greater than noradrenaline (IC50 3.9 microM) greater than [D-Ala2,MePhe4,Gly-ol5]enkephalin (IC50 8.5 microM) greater than prolongation of the action potential (41% increase by 30 microM). Stereoselectivity was observed only in the depression of responses to N-methyl-D-aspartic acid where (+)-1-(1-phenylcyclohexyl)-3-methyl piperidine was 3.3-fold more potent in suppressing N-methyl-D-aspartic acid depolarizations than its (-) isomer. The responses to N-methyl-D-aspartic acid were also depressed by the structurally unrelated psychotomimetic (+/-)-N-allyl-N-normetazocine (IC50 0.9 microM). All of the effects of the psychotomimetic drugs examined were slow in onset and difficult to reverse following washout. No effect of phencyclidine (0.03-100 microM) or related drugs was observed on membrane potential, input resistance or spontaneous action potential firing rate of locus coeruleus neurones. The depression of responses to N-methyl-D-aspartic acid by phencyclidine was the most potent and the only stereoselective effect of those studied. The importance of this effect and of those not showing stereoselectivity in relation to the phencyclidine behavioural syndrome is discussed.
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PMID:Actions of phencyclidine on rat locus coeruleus neurones in vitro. 351 91

1. The effects of strychnine on the degree of depression of neuronal firing induced by glycine, gamma-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) have been examined quantitatively. All drugs were applied by iontophoresis to spontaneously active cerebral cortical neurones in the anaesthetized cat. The application of these drugs was continued until a plateau or equilibrium depression was reached. The time taken to reach this steady state was noted. Dose-response curves were then constructed for those currents giving less than complete depression.2. Glycine was less potent than GABA and about 7-fold larger currents were needed to achieve comparable depression. 5-HT was also a weak depressant compared with GABA and had 0.6 the potency of glycine on a current basis.3. Strychnine in currents up to 25 nA shifted the dose-response curve of glycine to the right at a time when equilibrium depression in the same cells induced by the control agonists GABA or 5-HT was unaffected. These currents of strychnine did, however, prolong the time-course of onset of GABA and 5-HT depression.4. In larger currents strychnine reduced GABA equilibrium depression, but the dose-response curve was not shifted in a parallel fashion.5. It is concluded that strychnine can specifically and competitively antagonize the effect of glycine on cortical neurones.
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PMID:Amino-acid induced depression of cortical neurones. 544 89

It has been proposed that various opiate receptor subtypes mediate different cardiovascular responses to centrally administered opioids. We evaluated this hypothesis in chloralose-urethane anesthetized cats by monitoring the cardiovascular and respiratory responses to relative mu [morphine, morphiceptin, D-Ala2, MePhe4, Gly-ol5 enkephalin (DAGO)] and delta [D-Ala2, D-Leu5enkephalin (DADL)] agonists microinjected (0.5 ul/kg) into the caudal region of the Nucleus of Tractus Solitarius (NTS). Dynorphin (1-13), an endogenous opioid which exhibits selective affinity towards the kappa receptor, was also tested. Dynorphin at a dose of 50 nMol/kg did not alter cardiovascular or respiratory variables. Morphine (10-54 nMol/kg) and DAGO (50 nMol/kg) had no effect on blood pressure, heart rate or respiratory rate; morphiceptin (100-320 nMol/kg) caused tachycardia only at the highest dose. DADL (10-100 nMol/kg) elicited a dose-dependent depression of blood pressure. High doses of DADL depressed heart rate and respiratory rate. The depressor effects of DADL were reversed by low doses of naloxone (0.1 mg/kg). This dose of naloxone also elicited pressor responses in cats treated with the other opioids and reversed the morphiceptin-induced tachycardia. These data indicate that opioid agonists differ with regard to their cardiovascular and respiratory effects following microinjection into the NTS of anesthetized cats, with the delta agonist DADL showing greatest activity.
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PMID:Cardiovascular responses to opioid agonists injected into the nucleus of tractus solitarius of anesthetized cats. 613 54

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