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

The transport of indole-3-acetic acid-1-(14)C (IAA) through 4 mm segments of etiolated Avena coleoptiles was studied as a function of time by applying IAA in apical agar blocks and measuring the basal IAA export rate at 5-minute intervals. The transport velocity found in this way is at least 15 mm/hour at 26 degrees . Following a 30-minute equilibration period, the export rate is nearly constant for at least 50 minutes at physiological donor concentrations. Exposure to about 3 x 10(5) ergs/cm(2) blue light for 15 minutes leads to a transient reduction in the export. The export rate reaches a minimum about 25 minutes after the onset of illumination, then rises to reach a maximum by 35 minutes, and subsequently declines again. The result is a net export depression during the first 80 minutes, amounting to some 12 to 17%. Its timing closely matches the timing of the light growth response elicited by the same light dosage.At higher IAA concentrations (0.5 and 1.8 mg/l), the export rate reaches a peak about 60 minutes after the initial application of auxin, and thereafter declines rapidly. Light increases this decline in export rate, without causing peaks and troughs, and even at 0.25 mg/l IAA the transient changes in export appear to be superimposed on a gradual decline in export rate after illumination. Blue light is effective in all these phenomena; the red far-red system appears to exert no effect. The results are discussed in relation to the mechanism of action of light both in the light growth response and in phototropism.
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PMID:Transient effects of light on auxin transport in the Avena coleoptile. 1665 2

Pleasant and unpleasant flavors and odors can modulate pain perception, and the efficacy of sweet flavors in reducing pain seems to be related to its hedonic value. Chronic variate stress paradigm is a model of depression, and is suggested to induce anhedonia. We observed previously that lithium may prevent behavioral and neurochemical alterations induced by chronic stress; so we hypothesized that chronically stressed animals may present different nociceptive response to pleasant and unpleasant tastes that could be prevented by lithium treatment. Adult male Wistar rats were divided into four groups, control and stressed, treated or not with lithium. A Chronic Variate Stress paradigm was used, and lithium was added to the chow. After 40 days of treatment, the tail flick latency of the animals was evaluated, and rats were immediately placed in a box with access to a 5% acetic acid solution (acid flavor). After 5 min, tail flick latency was measured again. On the following day, animals were submitted to the same procedure, with the substitution of acetic acid by condensed sweet milk (sweet flavor). The stressed group was the only group who did not present analgesia after sweet taste exposition. All groups, except the control group, presented increased tail flick latency after exposition to the acid flavor. These results indicate that pleasant and unpleasant flavors present different relevance for the induction of antinociception in stressed animals, and the absence of sweet flavor-induced analgesia may represent an anhedonic effect of the chronic variate stress paradigm. On the other hand, perception of different flavors may be more prominent in animals treated with lithium.
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PMID:The nociceptive response of stressed and lithium-treated rats is differently modulated by different flavors. 1680 30

Decreased serotonin (5-HT) transmission is thought to underlie several mental diseases, including depression and feeding disorders. However, whether deficits in genes encoding G protein-coupled receptors may down-regulate the activity of 5-HT neurons is unknown currently. Based on recent evidence that stress-induced anorexia may involve 5-HT(4)receptors (5-HT(4)R), we measured various aspects of 5-HT function in 5-HT(4)R knock-out (KO) mice. When compared to dorsal raphe nucleus (DRN) 5-HT neurons from wild-type mice, those from 5-HT(4)R KO mice exhibited reduced spontaneous electrical activity. This reduced activity was associated with diminished tissue levels of 5-HT and its main metabolite, 5-hydroxyindole acetic acid (5-HIAA). Cumulative, systemic doses of the 5-HT uptake blocker citalopram, that reduced 5-HT cell firing by 30% in wild-type animals, completely inhibited 5-HT neuron firing in the KO mice. This effect was reversed by administration of the 5-HT(1A) receptor (5-HT(1A)R) antagonist, WAY100635, in mice of both genotypes. Other changes in DRN of the KO mice included increases in the levels of 5-HT plasma membrane transporter sites and mRNA, as well as a decrease in the density of 5-HT(1A)R sites without any change in 5-HT(1A) mRNA content. With the exception of increased 5-HT turnover index in the hypothalamus and nucleus accumbens and a decreased density of 5-HT(1A)R sites in the dorsal hippocampus (CA1) and septum, no major changes were detected in 5-HT territories of projection, suggesting region-specific adaptive changes. The mechanisms whereby 5-HT(4)R mediate a tonic positive influence on the firing activity of DRN 5-HT neurons and 5-HT content remain to be determined.
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PMID:Adaptive changes in serotonin neurons of the raphe nuclei in 5-HT(4) receptor knock-out mouse. 1693 Apr 32

Parasympathetic nerve (PSN) innervates taste cells of the frog taste disk, and electrical stimulation of PSN elicited a slow hyperpolarizing potential (HP) in taste cells. Here we report that gustatory receptor potentials in frog taste cells are depressed by PSN-induced slow HPs. When PSN was stimulated at 30 Hz during generation of taste cell responses, the large amplitude of depolarizing receptor potential for 1 M NaCl and 1 mM acetic acid was depressed by approximately 40% by slow HPs, but the small amplitude of the depolarizing receptor potential for 10 mM quinine-HCl (Q-HCl) and 1 M sucrose was completely depressed by slow HPs and furthermore changed to the hyperpolarizing direction. The duration of the depolarizing receptor potentials depressed by slow HPs prolonged with increasing period of PSN stimulation. As tastant-induced depolarizing receptor potentials were increased, the amplitude of PSN-induced slow HPs inhibiting the receptor potentials gradually decreased. The mean reversal potentials of the slow HPs were approximately -1 mV under NaCl and acetic acid stimulations, but approximately -14 mV under Q-HCl and sucrose stimulations. This implies that when a slow HP was evoked on the same amplitude of depolarizing receptor potentials, the depression of the NaCl and acetic acid responses in taste cells was larger than that of Q-HCl and sucrose responses. It is concluded that slow HP-induced depression of gustatory depolarizing receptor potentials derives from the interaction between gustatory receptor current and slow hyperpolarizing current in frog taste cells and that the interaction is stronger for NaCl and acetic acid stimulations than for Q-HCl and sucrose stimulations.
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PMID:Depression of gustatory receptor potential in frog taste cell by parasympathetic nerve-induced slow hyperpolarizing potential. 1695 70

Adverse experiences early in life are associated with an increased incidence of later psychopathology including depression. Based on evidence that dysfunction of central monoaminergic systems is involved in the pathophysiology of depression, we hypothesize that early adversity could negatively affect these systems. To test this we have investigated the effects of maternal separation, which has been suggested to model early-life stress and the development of a depression-like syndrome in the rat, on brain monoaminergic systems. Since depression is more common in women and the risk of developing this disorder appears to increase with age, we have studied such effects in middle-aged female rats. Rat pups were separated for 180 min (long maternal separation; LMS) or 15 min (brief maternal separation; BMS, often referred to as neonatal handling) twice daily for 2 weeks postpartum. An animal facility-reared (AFR) group was also included. At 15 months of age tissue levels of monoamines and their metabolites in several different brain regions were analyzed. In the LMS females tissue levels of both 5-HT and 5-hydroxyindole acetic acid (5-HIAA) were significantly increased in the dorsal raphe nucleus, and 5-HIAA and homovanillic acid levels were also elevated in the nucleus accumbens as compared with AFR and BMS rats. In the cingulate cortex both LMS and BMS decreased noradrenaline (NA) levels, although this effect was more pronounced in the LMS rats. On the other hand, BMS decreased 5-HT, 5-HIAA, dopamine (DA) as well as NA levels in the amygdala and produced an increase in DA levels in response to acute stress in the hypothalamus, an effect not seen in AFR rats. Our results demonstrate that LMS produced persistent alterations in both serotonergic, noradrenergic and dopaminergic systems in brain regions that have been suggested to be implicated in the pathophysiology of depression. In addition, BMS affected brain monoaminergic levels mainly in the amygdala.
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PMID:Both long and brief maternal separation produces persistent changes in tissue levels of brain monoamines in middle-aged female rats. 1722 17

This study was conducted to examine the pathophysiologic mechanisms of long-term adverse effects by neonatal maternal separation on neurobehaviors of the offspring. Sprague-Dawley pups were separated from dam daily for 180min during the first 2 weeks of life (MS) or undisturbed (NH), and subjected to behavioral sessions for ambulatory activity, forced swim, and elevated plus maze tests at 2 months of age. Serotonin reuptake transporter (5-HTT) mRNA levels in the raphe nucleus and the contents of serotonin (5-HT) and its metabolite 5-hydroxyindol acetic acid in the raphe and the hippocampus were examined as well. Ambulatory counts decreased and immobility duration in swim test increased in MS rats compared with NH rats. MS rats spent more time in the closed arms, less time in the open arms, of elevated plus maze, compared to NH rats. The hippocampal contents of 5-HT and the raphe expression of 5-HTT mRNA were decreased in MS rats compared with NH rats. These results suggest that neonatal maternal separation may result in the development of depression- and/or anxiety-like behaviors in later life, in which the long-term alterations in 5-HTergic neurotransmission may take a role.
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PMID:Depressive behaviors and decreased expression of serotonin reuptake transporter in rats that experienced neonatal maternal separation. 1729 51

The group I metabotropic glutamate receptors, mGluR1 and mGluR5, exhibit differences in their regulation of synaptic plasticity, suggesting that these receptors may subserve separate functional roles in information storage. In addition, although effects in vivo are consistently described, conflicting reports of the involvement of mGluRs in hippocampal synaptic plasticity in vitro exist. We therefore addressed the involvement of mGluR1 and mGluR5 in long-term potentiation (LTP) and long-term depression (LTD) in the hippocampal CA1 region of adult male rats in vitro. The mGluR1 antagonist (S)-(+)-alpha-amino-4-carboxy-2-methylbenzene-acetic acid (LY367385) impaired both induction and late phases of both LTP and LTD, when applied before high-frequency tetanization (HFT; 100 Hz) or low-frequency stimulation (LFS; 1 Hz), respectively. Application after either HFT or LFS had no effect. The mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP), when given before HFT, inhibited both the induction and late phases of LTP. When given after HFT, late LTP was inhibited. MPEP, given prior to LFS, impaired LTD induction, although stable LTD was still expressed. Application after LFS significantly impaired late phases of LTD. Activation of protein synthesis may comprise a key mechanism underlying the group I mGluR contribution to synaptic plasticity. The mGluR5 agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG) converted short-term depression into LTD. Effects were prevented by application of the protein synthesis inhibitor anisomycin, suggesting that protein synthesis is triggered by group I mGluR activation to enable persistency of synaptic plasticity. Taken together, these data support the notion that both mGluR1 and mGluR5 are critically involved in bidirectional synaptic plasticity in the CA1 region and may enable functional differences in information encoding through LTP and LTD.
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PMID:Metabotropic glutamate receptor 1 (mGluR1) and 5 (mGluR5) regulate late phases of LTP and LTD in the hippocampal CA1 region in vitro. 1836 18

The dried extracts of aerial parts of Cynodon dactylon Pers. (Graminae) were evaluated for CNS activities in mice. The ethanol extract of aerial parts of C. dactylon (EECD) was found to cause significant depression in general behavioral profiles in mice. EECD significantly potentiated the sleeping time in mice induced by standard hypnotics viz. pentobarbitone sodium, diazepam, and meprobamate in a dose dependant manner. EECD showed significant analgesic properties as evidenced by the significant reduction in the number of writhes and stretches induced in mice by 1.2% acetic acid solution. It also potentiated analgesia induced by morphine and pethidine in mice. EECD inhibited the onset and the incidence of convulsion in a dose dependent manner against pentylenetetrazole (PTZ)-induced convulsion. The present study indicates that EECD has significant CNS depressant activities.
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PMID:Evaluation of CNS activities of aerial parts of Cynodon dactylon Pers. in mice. 1853 71

Viral diseases of the brain may induce changes in neurotransmitter synthesis and metabolism. In experimental herpes simplex encephalitis, brain serotonin is reduced, whilst it's major metabolite, 5-hydroxyindole acetic acid and turnover is increased. It is well established that reduced levels of brain monoamines, serotonin and norepinephrine may contribute to the symptoms of clinical depression, which raises the possibility that this condition is prevalent in herpes simplex encephalitis. An inverse relationship exists between liver tryptophan-2,3-dioxygenase activity and brain serotonin levels and there is an interdependency between serotonin and norepinephrine levels. The aim of this study is to determine the effect of acyclovir, an antiviral used in the treatment of herpes simplex encephalitis, on rat liver tryptophan-2,3-dioxygenase activity in vitro and in vivo as well as on rat forebrain serotonin, 5-hydroxyindole acetic acid and norepinephrine levels. The results show that acyclovir inhibits tryptophan-2,3-dioxygenase activity in vitro and in vivo, with a concomitant rise in serotonin and 5-hydroxyindole acetic acid levels. However, acyclovir reduces the turnover of serotonin to 5-hydroxyindole acetic acid, without any effect on norepinephrine levels. It appears that acyclovir may have the potential to reduce the clinical symptoms of depression in herpes simplex encephalitis. However, a greater turnover of serotonin to 5-hydroxyindole acetic acid could possibly be masked by conversion of serotonin to 5-hydroxytryptophol, which needs to be investigated further.
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PMID:Acyclovir inhibits rat liver tryptophan-2,3-dioxygenase and induces a concomitant rise in brain serotonin and 5-hydroxyindole acetic acid levels. 1866 39

Ingestion of high levels of rapidly fermented carbohydrates after parturition often leads to the production of excessive quantities of organic acids that may exceed the buffering capacity of the rumen and cause pH to drop. Ruminal acidosis results in animal discomfort, anorexia, depression, decreased digestibility, and decreased milk production. In the present study, we examined the effects of daily addition of cells of a newly isolated strain of Prevotella bryantii (25A) to the rumen of 12 ruminally cannulated cows in early lactation. This strain was selected based on earlier in vitro studies that indicated its ability to grow rapidly, compete for starch, and produce organic acids other than lactate. After calving, all cows received increasing amounts of an energy-dense diet containing barley grain, corn silage, and grass silage in a 40:60 forage-to-concentrate ratio. Animals were blocked according to milk production from their previous lactation. Treatments (control and P. bryantii) were distributed among cows within the same block. Cows were fed once a day. Six cows were given a daily dose of P. bryantii (2 x 10(11) cells/dose), administered directly with a syringe through the rumen cannula, from 3 wk prepartum up to 7 wk postpartum. Rumen fluid was sampled before feeding and at 2 and 3 h postfeeding on wk 1, 2, 3, 4, 6, and 7 postpartum. Feed intake and milk yield were recorded daily and milk composition was recorded 2 d/wk, up to wk 7 of lactation. Feed intake was similar between control and treated cows. Prevotella bryantii did not change milk production, but milk fat tended to be greater in treated cows compared with control cows (3.9 vs. 3.5%). Rumen pH was similar between the 2 groups and differed across sampling times, being higher before feeding (6.3) as opposed to 2 h (5.9) and 3 h (5.7) postfeeding. Rumen lactate concentration was similar before feeding between control and treated cows; however, 2 to 3 h after feeding, lactate concentration was lower in cows receiving P. bryantii compared with control cows (0.7 vs. 1.4 mM). This difference was maintained throughout the experimental period. Concentration of NH(3)-N was greater in treated cows than in control cows (174 vs. 142 mg/L). Acetate (65.5 vs. 57.8 mM), butyrate (12.7 vs. 10.5 mM), and branched-chain C4 fatty acid (0.90 vs. 0.75 mM) concentrations were greater in postfeeding samples of treated cows compared with control cows. Supplementing early-lactating cows with P. bryantii 25A increased ruminal fermentation products and milk fat concentration. Because signs of subacute ruminal acidosis were not observed in either treated or control cows, no conclusions can be made about possible protection against acidosis by P. bryantii.
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PMID:Prevotella bryantii 25A used as a probiotic in early-lactation dairy cows: effect on ruminal fermentation characteristics, milk production, and milk composition. 1876 12


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