UMLS:C0011570 - FACTA Search

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Query: UMLS:C0011570 (depression)
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The role of GABAb receptor activation in the expression of both interictal and ictal phenomena was investigated in slices of area CA3 of the rat hippocampal formation. Interictal-like bursts occurred following application of high frequency trains to the Schaffer collaterals. When two bursts were triggered using paired stimuli, profound depression of the second burst was seen 150-600 ms following the first burst. GABAb receptor antagonists potently reversed the paired pulse depression of the interictal-like bursts. Reversal of the paired depression was also accomplished by increasing the extracellular concentration of K+ by 2-3 mM. Additional experiments were performed in area CA3 to determine the role of GABAb receptor activation on the expression of ictal phenomena. Electrographic seizures (EGSs) were induced by application of high frequency trains. 2-Hydroxy-saclofen (200 microM) significantly decreased the duration of trains required to elicit EGSs. Taken together, these data suggest that GABAb receptor activation has potent inhibitory effects on both ictal and interictal-like events.
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PMID:Antiepileptic effects of GABAb receptor activation in area CA3 of rat hippocampus. 838 98

Subregional distributions of serotonin1A receptors and serotonin transporters within the human dorsal raphe nucleus (DR) were determined by quantitative autoradiographic analyses of radioligand binding in tissue sections. [3H]8-Hydroxy-2-(di-n-propyl)aminotetralin (8-OH-DPAT) and [3H]paroxetine were used to label, respectively, serotonin1A receptors and serotonin transporters in the subnuclei of the DR, which were delineated on the basis of tryptophan hydroxylase (TrpOH) immunoreactivity. [3H]8-OH-DPAT binding was coextensive with the TrpOH-immunoreactive cell bodies and fibers but was distributed unevenly among the subnuclei. In contrast, [3H]paroxetine binding was present throughout the central gray matter, with relatively homogeneous labeling across the subnuclei of the DR. In rostral sections, [3H]8-OH-DPAT binding (fmol/mg protein) in the dorsal subnucleus was lower than that in the ventral or the interfascicular subnucleus. Within the interfascicular subnucleus, [3H]8-OH-DPAT binding decreased progressively in a rostral-to-caudal fashion. The highest levels of [3H]8-OH-DPAT binding were found in the ventrolateral subnucleus at the level of the caudal extent of the trochlear nucleus. The influence of age and postmortem interval on radioligand binding was also examined. These data in the human DR indicate that serotonin1A receptors are differentially distributed among the subnuclei and along the rostro-caudal axis of the midbrain raphe, and serotonin transporters appear to be relatively evenly distributed throughout the DR. Subregional analyses of such serotonergic markers may prove useful in evaluating the role that serotonin may play in depression, schizophrenia, and suicide.
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PMID:Quantitative subregional distribution of serotonin1A receptors and serotonin transporters in the human dorsal raphe. 884 77

1. Although conscious dogs have often been used for colonic motility studies with 5-hydroxytryptamine (5-HT), the effects of 5-HT on the isolated colon have not been thoroughly characterized yet. The current study was undertaken to characterize the response to 5-HT of the canine isolated colon longitudinal muscle. 2. Longitudinal strips of canine midcolon deprived of (sub)mucosa were prepared for isotonic measurement. 5-HT induced contractions from 3 nM onwards, which were not affected by selective inhibition of 5-HT re-uptake, monoamine oxidase or blockade of alpha-adrenoceptors. Tetrodotoxin (0.3 microM) did not affect the responses to 5-HT, suggesting that smooth muscle 5-HT receptors are involved. The selective 5-HT4 receptor antagonist SB 204070 (10 nM) slightly enhanced contractions to 5-HT and therefore it was included in the organ bath solution in all further experiments. The 5-HT1 and 5-HT2 receptor antagonist methysergide (0.1 microM) depressed the curve to 5-HT, but the selective 5-HT3 receptor antagonist granisetron (0.3 microM) had no effect. 3. Besides 5-HT, alpha-methyl-5-HT (alpha-Me-5-HT), 5-methoxytryptamine (5-MeOT), 2-methyl-5-HT (2-Me-5-HT) and 5-carboxamidotryptamine (5-CT) also induced contractions, with the following rank order of potency (pEC50 values in parentheses): 5-HT (6.9) = alpha-methyl-5-HT (6.9) > 2-Me-5-HT (5.8) = 5-MeOT (5.7) = 5-CT (5.6), indicative of 5-HT2 receptor involvement, alpha-Me-5-HT produced a bell-shaped curve, which was not affected by alpha-adrenoceptor blockade. 5-HT, 5-MeOT, 2-Me-5-HT and 5-CT produced a monophasic concentration-response curve, consistent with an interaction with a single receptor site. 8-Hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) and tryptamine only induced contractions at a concentration exceeding 1 microM. 4. The selective 5-HT2B receptor antagonist SB 204741 (0.3 microM) did not affect the curve to 5-HT. Ketanserin, cisapride and spiroxatrine behaved as competitive antagonists with pKb values of, respectively, 8.4, 8.1 and 6.7. Spiroxatrine (1 microM) shifted the curve to 5-MeOT rightward yielding an apparent pA2 of 7.1. Other antagonists at 5-HT2A receptors also surmountably inhibited the contractions to 5-HT (apparent pA2 value in parentheses): mesulergine (8.2), cinanserin (8.2), yohimbine (6.2) and mianserin (8.6). However, as well as a rightward shift, methiothepin (8.3), pizotifen (8.6) and spiperone (8.8) also caused a depression of the curve, indicative of "pseudo-irreversible' antagonism. Taken together, the above mentioned affinity estimates most closely corresponded to literature affinity values for 5-HT2A receptors. 5. It was concluded that 5-HT induces contractions of the canine midcolon longitudinal muscle primarily by stimulation of smooth muscle 5-HT2A receptors. The presence of inhibitory 5-HT4 receptors cannot be ruled out.
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PMID:Characterization of the contraction to 5-HT in the canine colon longitudinal muscle. 905 13

The effects of the ionic atmosphere on the enthalpic and entropic contributions to the reduction potential of native (state III) beef heart cytochrome c have been determined through variable-temperature direct electrochemistry experiments. At neutral or slightly alkaline pH values, from 5 to 50 degrees C, the reduction enthalpy and entropy become less negative with decreasing ionic strength. The reduction entropy extrapolated at null ionic strength is approximately zero, indicating that, in the absence of the screening effects of the salt ions on the network of the electrostatic interactions at the protein-solvent interface, the solvation properties and the conformational flexibility of the two redox states are comparable. The moderate decrease in E degrees' observed with increasing ionic strength [DeltaE degrees'IS = (E degrees')I = 0.1 M - (E degrees')I = (0)M = -0.035 V at 25 degrees C], once the compensating enthalpic and entropic effects of the salt-induced changes in the hydrogen bonding within the hydration sphere of the molecule in the two redox states are factored out, results in being ultimately determined by the stabilizing enthalpic effect of the negatively charged ionic atmosphere on the ferri form. At pH 9, the ionic strength dependence of the reduction termodynamics of cytochrome c follows distinctive patterns, possibly as a result of specific binding of the hydroxide ion to the protein. A decrease in ionic strength at constant pH, as well as a pH increase at constant ionic strength, induces a depression of the temperature of the transition from the low-T to high-T conformer of cytochrome c, which suggests that a temperature-induced decrease in the pK(a) for a residue deprotonation is the key event of this conformational change.
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PMID:Effects of nonspecific ion-protein interactions on the redox chemistry of cytochrome c. 1055 Jun 89

Six Nubian goats were exposed to an azalea branch (Rhododendron indica) at the Riverbanks Zoological Park in Columbia, South Carolina. The following day, 3 of the 6 goats were referred to the veterinary hospital of the Riverbanks Zoological Park with bloat, profuseregurgitation, and signs of depression, intermittent head pressing, and fine muscle tremors in the hind limbs. The goats were treated with magnesium hydroxide, activated charcoal, and lactated Ringer's solution and recovered within 24 hours. Definitive diagnosis of grayanotoxin exposure was accomplished by use of liquid chromatography-mass spectrometry analysis of urine and fecal samples. Rhododendron spp are members of the Ericaceae (Heath) family and may contain grayanotoxins, which exert toxic effects by binding to sodium channels in cell membranes and increasing the permeability of sodium ions in excitable membranes. Rhododendron poisoning should be considered in animals with clinical evidence of gastrointestinal tract irritation, cardiac arrhythmias, and neurologic signs.
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PMID:Grayanotoxin poisoning in three goats. 1122 12

The rates and products of the reactions of (+/-)-7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (1) and (+/-)-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (2) in water and dioxane-water mixtures have been determined over a pH range wider than that of earlier studies. This study provides additional insight on the mechanisms of the pH-independent reactions of 1 and 2. The rate profile for reaction of 1 shows acid-catalyzed hydrolysis at pH <5, a rate plateau at pH 5-9.5, a negative inflection at pH 10-11.5, and a rate increase at pH >11.5. The rate decrease between pH 10 and pH 11.5 is accompanied by a decrease in the yield of tetrols from 60% (pH 8) to 29% (pH 11.2) and is interpreted to be the result of a partial change in mechanism brought about by attack of hydroxide ion acting as a base to deprotonate a carbocation intermediate and regenerate 1 at pH >10, thus reducing the contribution of the pathway for tetrol formation in which water attacks the carbocation. The rate profile for the reaction of 2 exhibits only a single rate plateau at intermediate pH, along with increases in rate at low and high pH because of second-order reactions of 2 with H+ and HO-, respectively. The lack of a rate depression at pH >10 and the product studies for the reaction of 2 in dilute sodium azide solutions suggest that the tetrol-forming reactions of the pH-independent reaction of 2 are concerted or near-concerted.
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PMID:New insights on the mechanisms of the pH-independent reactions of benzo[a]pyrenes 7,8-diol 9,10-epoxides. 1144 82

(R)-8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) depressed the monosynaptic reflex. This effect was not antagonized by 5-HT(1A) receptor antagonists. We examined whether 5-HT(1D) and 5-HT(7) receptors are involved in (R)-8-OH-DPAT-induced inhibition of the monosynaptic reflex in spinalized rats. Pretreatment with methiothepin and mesulergine, but not clozapine, inhibited (R)-8-OH-DPAT-induced monosynaptic reflex depression. Pretreatment with 2a-(4-phenyl-1,2,3,6-tetrahydropyridal)butyl)-2a,3,4,5-tetrahydrobenzo[c,d]indol-2(1H)-one (DR4004) and (R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]pyrolidine (SB-269970), new selective 5-HT(7) receptors antagonists, and N-[methoxy-3-(4-methyl-l-piperazinyl)phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)[1,1-biphenyl]-4-carboxamide (GR127935), a selective 5-HT(1D) receptor antagonist, had no effect on (R)-8-OH-DPAT-induced depression. These results suggested that 5-HT(7) and 5-HT(1D) receptors are not involved in (R)-8-OH-DPAT-induced monosynaptic reflex depression.
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PMID:No involvement of 5-HT(7) or 5-HT(1D) receptors in the (R)-8-OH-DPAT-induced depression of the monosynaptic reflex in spinalized rats. 1155 64

Fluoxetine (Prozac) is currently one of the widely prescribed selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression. A high-throughput sample preparation procedure using liquid-liquid extraction (LLE) in a 96-well plate format in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed and validated for quantification of fluoxetine enantiomers in human plasma. After addition of internal standard and ammonium hydroxide, samples were extracted with ethyl acetate. The organic extract was evaporated to dryness and reconstituted in methanol. Where possible, sample transfer and LLE steps were automated using a Tomtec Quadra 96 workstation. Adequate separation of fluoxetine enantiomeric pairs (resolution of 1.17) was achieved on a vancomycin column eluted with methanol containing 0.075% (by weight) ammonium trifluoroacetate. A triple quadrupole mass spectrometer, operated in the multiple reaction monitoring mode at m/z 310-->44 for fluoxetine enantiomeric pairs and m/z 287-->241 for oxazepam (internal standard), was used. Analysis was performed in the positive ion mode using atmospheric pressure chemical ionization (APCI). The standard curve range was 2.0-1000 ng/mL for each fluoxetine enantiomer. The intra- and inter-day precision and accuracy of the quality control (QC) samples were <12.5% (CV) and <13.6% (CV), respectively, for each fluoxetine enantiomer; the correlation coefficient was >0.990. Method ruggedness was demonstrated by the reproducible performance of the assay during a three-day validation period.
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PMID:Enantiomeric separation and quantification of fluoxetine (Prozac) in human plasma by liquid chromatography/tandem mass spectrometry using liquid-liquid extraction in 96-well plate format. 1185 15

A bioassay of triphenyltin hydroxide for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. Triphenyltin hydroxide was administered in the feed, at either of two concentrations, to groups of 50 male and 50 female animals of each species. The high and low concentrations of triphenyltin hydroxide were, respectively, 75 and 37.5 ppm for rats and mice. After a 78-week period of compound administration, there was an additional observation period of 26 weeks for both species. Twenty animals of each sex and species were placed on test as controls. For male mice, there was a significant positive association between dosage and mortality. In both species, however, adequate numbers of animals survived sufficiently long to be at risk from late-developing tumors. Except for a slight depression of mean body weight gain in male rats and female mice, compound-related mean body weight depression was not observed in either species. In female rats no significant accelerated mortality, retardation of growth, or other signs of toxicity were associated with the dietary administration of triphenyltin hydroxide. Therefore, it is possible that the compound was not administered at the maximum tolerated concentrations. No tumors occurred at a significantly higher incidence in dosed rats or mice than in controls. Under the conditions of this bioassay, there was no evidence for the carcinogenicity of triphenyltin hydroxide to Fischer 344 rats or B6C3F1 mice.
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PMID:Bioassay of triphenyltin hydroxide for possible carcinogenicity. 1279 53

Corn steep water (CSW) and other byproducts derived from fermentations and sugar productions are presently forming the base of compositions for de-icing and anti-icing materials. Since the de-icing and anti-icing values are in part a colligative property, increase in the molar concentration of ionic species has been frequently necessary to decrease further the freezing point of this byproducts stream. In the present study this has been achieved by the generation of biodegradable organic acid salts in situ, without the use of chloride or other inorganic salts, by the alkaline degradation of reducing sugars added to corn steep water, which alone is not an efficient de-icer. Reducing sugars, such as glucose, react with alkali metal hydroxides to produce principally hydroxy carboxylic acids that react with the alkali metal hydroxide to form a mixture of organic acid salts. The ionic strength of the resulting solution is increased since each sugar molecule produces nearly two acid molecules upon degradation. The ionic strength necessary to achieve the desired freezing point depression is determined by the amount and concentration of the alkali metal hydroxide used, with the necessary counter anions being derived from the degradation of the reducing sugar. The amount of the sugar used is that required to result in a near to neutral final solution. The well-known anti-corrosive property of CSW is used in the de-icer preparations, either by conducting the alkaline degradation of the sugar in this medium, or by using water for the degradation of the sugar followed by dilution of the resulting solution with CSW to adjust the viscosity of the final solution to meet the requirements for spraying. The monovalent metal hydroxides are more efficient in producing de-icer solutions than the divalent metal hydroxides.
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PMID:De-icers derived from corn steep water. 1457 49

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