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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The positive inotropic responses of left atria and papillary muscles and the positive chronotropic responses of right atria of guinea-pigs to isoprenaline and forskolin were examined. An increase in sensitivity of the three preparations to isoprenaline was observed by lowering the bath temperature from 38 to 30 degrees C as demonstrated by a leftwards shift of the concentration-response curves. A similar degree of supersensitivity was observed for forskolin. Since forskolin is reputed to stimulate adenylate cyclase directly, whereas isoprenaline stimulates via the regulatory nucleotide Ns protein, this would suggest a common site for the supersensitivity at adenylate cyclase. However, the possibility that forskolin also stimulates via the Ns protein in producing cardiac stimulation and that this is the site of hypothermia-induced supersensitivity is discussed. Supersensitivity to isoprenaline was also observed in left atria and papillary muscles from guinea-pigs chronically pretreated with reserpine for 3 days (5 mg/kg at 72 h, 3 mg/kg at 48 and 24 h) or 7 days (0.1 mg/kg daily). In the same tissues, there was no change in the sensitivity to forskolin. The site of the supersensitivity can therefore be concluded to occur before the level of adenylate cyclase activation either directly or via the regulatory Ns protein; possibly at the beta-adrenoreceptor itself.
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PMID:The use of forskolin to investigate the site of cardiac beta-adrenoreceptor supersensitivity. 299 30

5'-Deoxy-5-iodotubercidin was previously reported to cause potent muscle relaxation and hypothermia when injected i.p. into mice. In normotensive rats, i.v. injection reduced blood pressure and heart rate. 5-Iodotubercidin possessed the same in vivo activities whereas tubercidin was pharmacologically almost inactive. None of these compounds interacted significantly with Al adenosine receptors, as determined by their ability to displace 3H-N6-phenylisopropyladenosine or 3H-5'-N-ethylcarboxamidoadenosine bound to rat brain membranes. Furthermore these compounds were much weaker than adenosine as agonists of adenosine-stimulated adenylate cyclase in guinea-pig brain slices (A2 receptors). A previous report showed that 5'-deoxy-5-iodotubercidin and 5-iodotubercidin were very potent inhibitors of adenosine kinase from rat or guinea-pig brain and were potent inhibitors of 3H-adenosine uptake into brain slices; relative to the halogenated derivatives, tubercidin was quite weak as an inhibitor of adenosine kinase and of adenosine uptake. We therefore propose that a significant part of the in vivo activity of the two halogenated tubercidin analogues may not be due to a direct agonist action at A1 and/or A2 adenosine sites (as proposed for a number of other metabolically-stable analogues of adenosine) but may result from an inhibition of reuptake of endogenously-released adenosine; the increased extracellular levels of adenosine resulting from this action could then interact directly with membrane receptors. Consistent with this, low concentrations of 5'-deoxy-5-iodotubercidin were shown to significantly potentiate the effects of exogenous adenosine on blood pressure and heart rate in anaesthetized rats and on adenosine-stimulated cAMP generation in guinea-pig brain slices. None of these compounds interacted with central benzodiazepine receptors. The cardiovascular and behavioural effects of 5'-deoxy-5-iodotubercidin and 5-iodotubercidin were blocked by theophylline; results from the cardiovascular studies suggest there may be different adenosine receptors in heart and blood vessels.
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PMID:Studies on several pyrrolo[2,3-d]pyrimidine analogues of adenosine which lack significant agonist activity at A1 and A2 receptors but have potent pharmacological activity in vivo. 301 53

Forskolin, a direct activator of the catalytic subunit of adenylate cyclase (AC), and the cyclic nucleotide analogs dibutyryl cAMP (dBcAMP), 8-bromo cAMP (8-BrcAMP) and dibutyryl cGMP (dBcGMP) were tested for their ability to reverse the hypothermia or hypokinesia of mice depleted of presynaptic endogenous monoamines by pretreatment with reserpine, alpha-methyl-p-tyrosine and p-chlorophenylalanine. Forskolin and the cAMP analogs decreased the rectal temperature and inhibited locomotor activity in normal mice. In mice depleted of brain monoamines forskolin reversed the hypothermia and hypokinesia; dBcAMP and 8-BrcAMP antagonized the hypothermia but were only marginally effective in reversing the hypokinesia. DBcGMP was inactive. The antihypothermic action of forskolin or salbutamol was enhanced by the novel antidepressant and cAMP selective phosphodiesterase inhibitor rolipram (4RS-[3-cyclopentyloxy-4-methoxy-phenyl]-2-pyrrolidone). As an indirect effect via release of endogenous monoamines stimulating postsynaptic receptors was precluded by the monoamine-depleting pretreatment, forskolin and the cAMP analogs are thought to exert their antidepressant action by directly increasing brain cAMP availability. This is achieved by forskolin via activation of the catalytic subunit of AC and by the cAMP analogs via substitution for cAMP. These findings suggest that antidepressant activity is crucially linked to enhanced cAMP availability within brain effector cells. The successful treatment of endogenously depressed patients with rolipram supports this assumption.
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PMID:Effects of forskolin and cyclic nucleotides in animal models predictive of antidepressant activity: interactions with rolipram. 302 33

The pharmacological properties of MO-8282 (1,2,3,4-tetrahydro-2-methyl-9H-dibenzo [3,4: 6,7]cyclohepta [1,2-c]pyridine maleate) as an antidepressant were investigated. At doses 10 times less than those of amitriptyline, MO-8282 showed similar potencies in reducing the duration of immobility during forced swimming in rats and in potentiating stereotype induced by L-DOPA. Intermediate doses of MO-8282 reduced the duration of immobility during forced swimming, in mice as well, suppressed muricide behavior of olfactory-bulbectomized rats and antagonized clonidine-induced suppression of exploratory activity in mice. MO-8282 moderately antagonized the ptosis but not the hypothermia induced by reserpine in mice. MO-8282 exhibited weak antagonism against the tremor, lacrimation and diarrhea induced by tremorine, but its activity was milder than that of amitriptyline. The uptake of noradrenaline into rat hypothalamic synaptosomes was inhibited by MO-8282 at concentrations 20 times less than equally effective doses of amitriptyline, but the uptake of dopamine or serotonin was unaffected by MO-8282. A single oral administration of MO-8282 at a dose of 30 mg/kg accelerated noradrenaline turnover, but did not affect dopamine and serotonin turnover in the rat brain. MO-8282 strongly inhibited noradrenaline-, histamine- or adenosine-sensitive adenylate cyclase activity of guinea pig brain. Its mode of action differed from that of imipramine, rather resembling that of mianserin. MO-8282 did not affect monoamine oxidase activity of rat liver. These results suggest that the pharmacological characteristics of MO-8282 are different from those of tricyclic antidepressants and rather similar to those of mianserin, but more potent. The results, therefore, indicate that MO-8282 is possibly a novel antidepressant.
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PMID:[Pharmacological properties of MO-8282, a novel antidepressant]. 379 61

A new benzamide, cis-N-(1-benzyl-2-methylpyrrolidin - 3 - yl) - 5 - chloro - 2 - methoxy - 4 - methylaminobenzamide (YM-09151-2) exhibited more potent and longer-lasting inhibitory effects on apomorphine-induced behaviours (stereotyped behaviour, emesis and hypothermia), and methamphetamine-induced stereotyped behaviour, conditioned avoidance response and open field behaviour, conditioned avoidance response and open field behaviour than either structurally similar benzamides (YM-0850 and sulpiride) or classical neuroleptics [chlorpromazine (CPZ) and haloperidol(HPD)]. Such inhibitory effects of YM-09151-2 relative to cataleptogenicity were greater than those of CPz and HPD. In contrast, sulpiride elicited few of the neuroleptic effects described above. YM-09151-2, a potent inhibitor for dopamine-sensitive adenylate cyclase (Ki: 3.0 nM) reduced, in a selective manner, the binding of [3H]dopamine to the dopamine D1 receptor (Ki:4.8 nm) associated with adenylate cyclase rather than to the dopamine D2 receptor (Ki: 0.98 microM) independent of adenylate cyclase. Sulpiride, on the contrary, inhibited only the binding to the dopamine D2 receptor, CPZ and HPD antagonized [3H]dopamine nonselectively at the two distinct dopaminergic receptors. These results suggest that YM-09151-2 is a potent and long-lasting neuroleptic with a highly selective blocking action on the dopamine D1 receptor.
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PMID:Neuroleptic properties of cis-N-(1-benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxy-4-methylaminobenzamide (YM-09151-2) with selective antidopaminergic activity. 611 70

SCH 23390 [R-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol) possesses pharmacologic effects similar to standard antipsychotics, including selective supression of conditioned avoidance responding in rats and squirrel monkeys, blockade of apomorphine-induced stereotypy in rats and blockade of methamphetamine-induced lethality in aggregated mice. At effective doses in these tests, no changes in gross behavior, neurological or autonomic function were observed. In contrast to the standards tested, SCH 23390 blocked dopamine-stimulated adenylate cyclase at concentrations (IC50 = 0.01 microM) about 2000 times lower than those needed to block spiperone binding (IC50 = 24 microM). This suggests specific D1-receptor antagonism. Inability of SCH 23390 to cause hyperprolactinemia, considered to be a D2-receptor effect, is consistent with this hypothesis. SCH 23390 showed lower increases in dopamine turnover suggesting that the blockade of SCH 23390 may be more specific for post- than presynaptic sites. Additional evidence for the selectivity of SCH 23390 among putative postsynaptic dopamine sites includes its lack of effect on apomorphine-induced hypothermia or emesis. Based on these results, it is postulated that SCH 23390 is a selective D1-receptor antagonist.
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PMID:SCH 23390, a potential benzazepine antipsychotic with unique interactions on dopaminergic systems. 613 95

Sertraline [1S,4S-N-methyl-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1-naphthylamine] was found to be a highly selective and potent competitive inhibitor of synaptosomal serotonin uptake. Sertraline also selectively reduced ex vivo uptake of serotonin and strongly antagonized the serotonin-depleting action of p-chloroamphetamine, indicating potent blockade of serotonin uptake in vivo. Acute and repeated dosing of sertraline decreased serotonin content of whole blood. Sertraline only weakly inhibited rat heart uptake of i.v. [3H]norepinephrine. In substantiation of selective blockade of serotonin uptake, sertraline potentiated various symptoms of 5-hydroxytryptophan but did not reverse reserpine-induced hypothermia. Sertraline was a very weak inhibitor of [3H]quinuclidinyl benzilate binding to rat brain membranes in vitro and did not produce anticholinergic effects in mice in vivo. Sertraline was well tolerated in mice, rats and dogs, with no locomotor stimulant effects in rats or untoward cardiovascular effects in dogs. The major metabolite, N-demethylsertraline, was also a selective serotonin uptake blocker. Sertraline strongly reduced immobility of mice in the Porsolt swim test for antidepressants. After repeated dosing in rats, sertraline diminished the cyclic AMP response of limbic forebrain adenylate cyclase to norepinephrine, as well as the binding of [3H]dihydroalprenolol to cortical membranes. It is proposed that selective blockade of serotonin reuptake can induce activation of norepinephrine neurons and subsequent down-regulation of norepinephrine receptors and that sertraline, a highly selective inhibitor of serotonin uptake, may be an efficacious antidepressant without anticholinergic or cardiovascular side-effects.
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PMID:Sertraline, 1S,4S-N-methyl-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1-naphthylamine, a new uptake inhibitor with selectivity for serotonin. 631 78

Two novel halogenated pyrrolopyrimidine analogues of adenosine, isolated from marine sources, have been examined for pharmacological and biochemical activities. 4-Amino-5-bromo-pyrrolo[2,3-d]pyrimidine, from a sponge of the genus Echinodictyum, had bronchodilator activity at least as potent as theophylline but with a different biochemical profile; unlike theophylline it had no antagonist activity at CNS adenosine receptors and it was quite a potent inhibitor of adenosine uptake and adenosine kinase in brain tissue. 5'-Deoxy-5-iodotubercidin, isolated from the red alga Hypnea valentiae, caused potent muscle relaxation and hypothermia when injected into mice. This compound was a very potent inhibitor of adenosine uptake into rat and guinea-pig brain slices and an extremely potent inhibitor of adenosine kinase from guinea-pig brain and rat brain and liver. Neither of these two pyrrolopyrimidine analogues was a substrate for, or an inhibitor of, adenosine deaminase. Neither compound appeared to have any direct agonist activity on guinea-pig brain adenosine-stimulated adenylate cyclase (A2 adenosine receptors). 5'-Deoxy-5-iodotubercidin is unique in two respects: it appears to be the first naturally-occurring example of a 5'-deoxyribosyl nucleoside and is the first example of a specifically iodinated nucleoside from natural sources. It may be the most potent adenosine kinase inhibitor yet described and, by virtue of its structure, may prove to be the most specific.
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PMID:Halogenated pyrrolopyrimidine analogues of adenosine from marine organisms: pharmacological activities and potent inhibition of adenosine kinase. 632

The N6-2'-O-dibutyryl derivative of adenosine 3',5'-monophosphate (db cyclic AMP) and related compounds have been micro-injected into the preoptic/anterior hypothalamic nuclei (PO/AH) of the unanaesthetized, restrained rabbit and the effects on deep body temperature observed. Db cyclic AMP (100-400 micrograms) produced hypothermia of rapid onset in rabbits at an ambient temperature of 20-23 degrees C. Hypothermia was also produced by N2-2'-O-dibutyryl guanosine 3',5'-monophosphate (db cyclic GMP), but not by saline, sodium n-butyrate, adenosine 3',5'-monophosphate (cyclic AMP), guanosine 3',5'-monophosphate, adenosine 5'-mono-, di- or triphosphate. The initial hypothermic response to db cyclic AMP and db cyclic GMP was followed by a sustained rise in temperature. However, all compounds injected into the PO/AH produced a similar hyperthermia which was attenuated by paracetamol. Development of this tissue-damage fever abolished the hypothermic response to db cyclic AMP in some rabbits. The effects of db cyclic AMP on body temperature and behaviour were not reproduced by the adenylate cyclase activators, cholera toxin (0.125-5 micrograms) and guanyl imidodiphosphate (5-400 micrograms). It is concluded that hypothermia is the principal effect of db cyclic AMP on body temperature when injected into the PO/AH in rabbits. These data do not support the proposal that endogenous cyclic AMP in the rabbit brain mediates pyrexia.
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PMID:Evidence that cyclic nucleotides are not mediators of fever in rabbits. 632 20

The (+)-enantiomer of 1,2,3,4a,5,6-hexahydro-9-hydroxy-4-n-propyl-4H-naphth[1,2-b][ 1,4]-oxazine [(+)-PHNO] is demonstrated to be a potent and direct dopamine (DA) agonist in several in vivo and in vitro test procedures. In vitro (+)-PHNO inhibited binding of [3H]apomorphine (IC50 = 23 nM) or [3H]spiperone (IC50 = 55 nM) to rat striatal membranes. Because (+)-PHNO failed to stimulate adenylate cyclase in carp retina, it was classified as a D-2 agonist. ED50 values (shown in parentheses) derived in DA receptor-related in vivo tests were as follows: in mice, (+)-PHNO produced hypothermia (13 micrograms/kg i.p.) and postural asymmetry in the unilaterally caudectomized animal (4 micrograms/kg i.p.). In the rat, (+)-PHNO produced stereotypy (10 micrograms/kg i.p.) and contralateral turning in 6-hydroxydopamine-lesioned animals (5 micrograms/kg i.p.) that lasted 1 to 3 hr. Whereas both of the latter effects were blocked by haloperidol, prior treatment with depletors of endogenous catecholamines, reserpine or alpha-methylparatyrosine failed to reduce (+)-PHNO-induced stereotypy. The naphthoxazine also produced emesis in beagles (0.05 micrograms/kg i.v.) that was blocked by L-646,462, a peripherally selective DA receptor antagonist. (+)-PHNO was well absorbed when given p.o., producing contralateral turning (10 micrograms/kg) with a ratio of p.o. to i.p. ED50 values of 2. This ratio was much lower than those derived for n-propylnorapomorphine (60) and apomorphine (54). At the DA autoreceptor, (+)-PHNO inhibited the accumulation of dOPA in the gamma-butyrolactone-treated rat (11 micrograms/kg i.p.).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pharmacologic profile of a novel potent direct-acting dopamine agonist, (+)-4-propyl-9-hydroxynaphthoxazine [(+)-PHNO]. 643


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