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

Recent claims to have demonstrated associative learning ability in Drosophila melanogaster raise questions about the adaptive significance of behavioral modifiability of this species. In a strain survey and a 9 X 9 half diallel cross study of olfactory discriminative avoidance conditioning, a low narrow heritability and strong directional dominance or heterosis controlling nonrandom phenotypic variation were found. Furthermore, the predicted inbreeding depression and asymmetrical response to bidirectional genetic selection were both observed. The genetic architecture revealed in these experiments is consistent with a close association between this conditioning phenotype and evolutionary fitness. Predictions from this interpretation to the nature of new mutations have been confirmed, and a possible role for conditioning in courtship behavior has been identified.
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PMID:Genetic architecture of olfactory discriminative avoidance conditioning in Drosophila melanogaster. 640

Increasing doses of pilocarpine, 100-400 mg/kg, were given intraperitoneally to mice and the resulting behavioral, electroencephalographic and neuropathological alterations were studied. No behavioral phenomena were observed in mice treated with the lowest dose of pilocarpine. Occasional tremor and myoclonus of hindlimbs were found in animals which received pilocarpine in a dose of 200 mg/kg. At doses of 300, 325 and 350 mg/kg, pilocarpine produced a sequence of behavioral alterations including staring spells, limbic gustatory automatisms and motor limbic seizures that developed over 15-30 min and built up progressively into a limbic status epilepticus lasting for several hours. The highest dose of pilocarpine, 400 mg/kg, was generally lethal to mice. Pilocarpine produced both interictal and ictal epileptiform activity in the electroencephalogram (EEG). The earliest EEG alterations appeared in the hippocampus and then spread to cortical areas. EEG seizures started 10-15 min after injection of large doses of pilocarpine, 300-350 mg/kg. Ictal periods lasted for 1-2 min, recurred every 5-10 min and were followed by periods of depression of the EEG activity. By 30-45 min paroxysmal activity resulted in a status epilepticus. Examination of frontal forebrain sections with light microscopy revealed a widespread damage to several brain regions including the hippocampus, amygdala, thalamus, olfactory cortex, neocortex and substantia nigra. Scopolamine, 10 mg/kg, and diazepam, 10 mg/kg, prevented the development of convulsive activity and brain damage produced by pilocarpine. The results emphasize that excessive and sustained stimulation of cholinergic receptors can lead to seizures and seizure-related brain damage in mice. It is proposed that systemic pilocarpine in mice provides a useful animal model for studying mechanisms of and therapeutic approaches to temporal lobe epilepsy.
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PMID:Seizures produced by pilocarpine in mice: a behavioral, electroencephalographic and morphological analysis. 649 17

The immediate vs. long-term effects of desmethylimipramine (DMI) or chlorimipramine (CMI) on cerebral blood flow (CBF) were determined in 17 rabbit brain regions using radioactively tagged microspheres (15 +/- 3 micron in diameter). A single administration of either drug did not alter average CBF or its regional distribution 1 h later. Desmethylimipramine, an agent which primarily blocks re-uptake in presynaptic noradrenergic neurons, significantly increased CBF when administered daily for 21 consecutive days. The regional effects of DMI were not restricted to those areas dense in noradrenergic receptors. Flow was significantly increased in the hypothalamus, olfactory cortex, globus pallidus-putamen and midbrain. These flow increases probably reflect integrated cerebral metabolic, synthetic and/or functional activity which were associated with altered receptor sensitivity and/or number, rather than a direct cerebral vasodilatory effect. In contrast, CMI, a tricyclic antidepressant which primarily blocks presynaptic re-uptake in serotonergic neurons, and produced sedation, had little effect on CBF when administered daily for 21 consecutive days. The immediate effects of these agents on presynaptic re-uptake was not associated with altered CBF. The long-term antidepressant activity of these two agents on receptor sensitivity was probably not correlated with CBF, as evidenced by the lack of effect which CMI had on this parameter. Rather, CBF response appears to be correlated with the therapeutic spectrum of DMI which increases psychomotor activity in retarded depression.
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PMID:Immediate vs. long-term desmethylimipramine or chlorimipramine: effects on regional cerebral blood flow. 652 65

Behavioural, electroencephalographic and neuropathological responses to increasing doses of pilocarpine (100-400 mg/kg) administered intraperitoneally to rats were studied. At the dose of 400 mg/kg pilocarpine produced a sequence of behavioural alterations including staring spells, olfactory and gustatory automatisms and motor limbic seizures that developed over 1-2 h and built up progressively into limbic status epilepticus. Smaller doses showed different threshold for these behavioural phenomena but a similar time course of development. The earliest electrographic alterations occurred in the hippocampus and then epileptiform activity propagated to amygdala and cortex. Subsequently electrographic seizures appeared in both limbic and cortical leads. The ictal periods recurred each 5-15 min and were followed by variable periods of depression of the electrographic activity. The sequence of electrographic changes correlated well with the development of behavioural phenomena. Histological examination of frontal forebrain sections revealed disseminated, apparently seizure-mediated pattern of brain damage. Neuropathological alterations were observed in the olfactory cortex, amygdaloid complex, thalamus, neocortex, hippocampal formation and substantia nigra. Pretreatment of animals with scopolamine (20 mg/kg) and diazepam (10 mg/kg) prevented the development of convulsive activity and brain damage. These results show that systemic pilocarpine in rats selectively elaborates epileptiform activity in the limbic structures accompanied by motor limbic seizures, limbic status epilepticus and widespread brain damage. It is suggested that a causative relationship between excessive stimulation of cholinergic receptors in the brain and epileptic brain damage may exist.
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PMID:Limbic seizures produced by pilocarpine in rats: behavioural, electroencephalographic and neuropathological study. 663 40

Olfactory bulbectomized rats and DSP4-treated rats were studied on a two-way active avoidance task as well as on step-down passive avoidance and fear conditioning and retention tasks in three experiments. The DSP4-treated, but not olfactory bulbectomized, rats were impaired in acquiring two-way avoidance; bulbectomized, but not DSP4-treated, rats were found to show notable passive avoidance and fear retention deficits. Bulbectomized rats treated with DSP4 did not show passive avoidance and fear retention deficits, nor did these animals evidence the two-way avoidance impairment of the DSP4-treated rats. No alteration of dopamine-beta-hydroxylase activity in the frontal cortex and hippocampus as a result of the bulbectomy operation was indicated. The double dissociation between bulbectomized and DSP4-treated rats is discussed in terms of opponent behavioral processes, influenced by olfactory bulbectomy and DSP4, which may permit insights into experimental investigations of stress, anxiety, and depression.
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PMID:Role of olfactory bulbectomy and DSP4 treatment in avoidance learning in the rat. 673 27

The vomeronasal organs of male guinea pigs were removed (VNX; n = 10) or males experienced sham surgery (Sham; n = 10). Subsequently a battery of chemosensory tests of investigatory responsiveness to conspecific urine was conducted. Additionally, male subjects were paired with female conspecifics for short and long periods and social and sexual behaviors were monitored. VNX males exhibited a depression in urine investigation and this depression became more profound following repeated testing and/or the passage of time. By 6.3 months following surgery, investigatory responsiveness to urine was practically eliminated. Maintenance of responsiveness to urine odors may require reinforcing input through the accessory olfactory system. In contrast to these effects on responsiveness to odors, VNX and Sham males were indistinguishable in their social and sexual behavior. These data indicate that male guinea pigs without a VNO: (1) Exhibit a depression of investigation of urine odors which is time dependent and which may involve an extinction-like process; (2) continue to discriminate classes of urine (e.g., urine from male vs urine from female conspecifics); and (3) exhibit normal sexual behavior. The vomeronasal organ in the male domestic guinea pig is apparently critical for the maintenance of normal responsiveness to sex odors but, in its absence, other sensory systems are capable of maintaining normal sexual behavior under conditions of laboratory testing.
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PMID:Chemoinvestigatory and sexual behavior of male guinea pigs following vomeronasal organ removal. 714 38

Pentobarbitone, phenobarbitone, methohexitone, chloralose and alphaxalone produced 10-fold increases in the duration of an inhibitory post-synaptic conductance (i.p.s.c.) as recorded intracellularly from neurones of the guinea-pig olfactory cortex in vitro. Higher concentrations slightly depolarised these neurones and reduced their input resistance (Ri), presumably a spontaneous activation of the inhibitory conductance. The excitatory potentials were also depressed. Ketamine, halothane and urethane doubled the i.p.s.c. duration. Higher concentrations depressed synaptic activity and the action potential, as did lignocaine. Ketamine also increased Ri. These results confirm the idea that these compounds produce anaesthesia by prolonging inhibition (accompanied by a depression of the e.p.s.p. with some anaesthetics).
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PMID:Potentiation of inhibition by general anaesthetics in neurones of the olfactory cortex in vitro. 719 Jun 80

Pharmacological properties of 2-(4-methylamino-butoxy)-diphenylmethane hydrochloride (MCI-2016) were examined in comparison with those of other antidepressants. MCI-2016 significantly antagonized the hypothermia and depression-like syndrome produced by reserpine injection. Furthermore, the drug exhibited such activities as antitetrabenazine and anti-cataleptic actions, and potentiation of the behavioural excitation induced by yohimbine, methamphetamine and L-dopa. MCI-2016 showed a definite suppressive effect on muricidal activity in olfactory bulb removed rats and the long-term isolation-induced fighting in mice without causing apparent motor disturbance. Judging from the effects of the drug on in vitro response to noradrenaline (NA) and serotonin (5-HT), and on p-chloramphetamine-induced hypermotility, it is suggested that MCI-2016 is a selective potentiator of NA presumably due to an inhibition of NA uptake. Anticholinergic and sedative actions of MCI-2016 were considerably weaker than those of amitriptyline and imipramine. Acute toxicity of MCI-2016 was the weakest among the drugs tested. These pharmacological profiles may suggest a potential clinical utility of MCI-2016 as a new psychotropic agent having an antidepressant activity.
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PMID:Pharmacological evaluation of 2-(4-methylaminobutoxy)diphenylmethane hydrochloride (MCI-2016), a new psychotropic drug with antidepressant activity. 719 35

This experiment examined how inescapable tail shock alters the level of dopamine and norepinephrine within various brain regions of the rat and the relationship of these changes to the depression of motor activity produced by the shock. Following exposure to tail shock that is known to interfere with acquisition of active behavioral tasks, animals were briefly tested for spontaneous motor activity and then sacrificed for neurochemical measures. Norepinephrine and dopamine levels in the frontal cortex, brain stem, striatum, olfactory tubercle, hypothalamus, hippocampus, septum, and amygdala were measured by a sensitive radioenzymatic technique. Exposure to 45 min of tail shock did not alter motor activity significantly, but shock sessions of 60 and 75 min duration produced a marked decrease in motor activity. Levels of dopamine were found to be very little changed in all brain regions studied except for the hypothalamus, in which a substantial rise in dopamine level was observed. Norepinephrine levels, in contrast, fell in many brain regions in response to shock. The fall in norepinephrine levels observed in two brain regions was significantly correlated with the decline in motor activity (brain stem r = +0.70, hypothalamus r = +0.60). These data suggest that deficits in active motor behavior produced by shock parameters similar to those used in this study may reflect concomitant disturbances of noradrenergic function in specific brain regions.
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PMID:Stress-induced depression of motor activity correlates with regional changes in brain norepinephrine but not in dopamine. 736 96

Male rats (25-26 days of age) housed with 14 hours of light per day (lights on 0600--2000 hours) were either olfactory bulbectomized (rendering them anosmic), bulbectomized plus pinealectomized (Pinx), or left intact. On the day following the operations, intact, anosmic, and anosmic-Pinx animals began receiving single, daily afternoon (1700--1800 hours) subcutaneous injections of 50 microgram of melatonin (MEL) for six weeks, while an additional group of intact controls received injections of diluent. At the end of this period, body, anterior pituitary, testicular, and seminal vesicle weights were significantly reduced in intact-MEL-treated animals. Anosmic animals that had been treated with MEL experienced a further, highly significant, 65%, 90%, and 85% depression in testicular, seminal vesicle, and ventral prostate weights, respectively, as compared with intact control and MEL-treated rats. Additionally, both body and anterior pituitary weights were significantly decreased in MEL-treated, anosmic rats. Anosmic-Pinx rats treated with MEL had organ and body weights that were intermediate between those of intact-MEL and anosmic-MEL-treated animals. Pituitary and serum levels of prolactin (Prl) were significantly lower in anosmic-MEL-treated rats than in intact-MEL-treated groups. Similarly, Prl levels were depressed in the anosmic-Pinx rats treated with MEL; however, serum Prl was not statistically lower than in intact or intact-MEL-treated animals. These results indicate that anosmic male rats have an increased sensitivity to antigonadotrophic and Prl-inhibitory effects of MEL. Futhermore, the data suggest that the presence of the pineal gland in anosmic rats is important in permitting anosmia maximally to sensitize the neuroendocrine-reproductive axis to the antigonadotrophic effects of exogenously administered MEL.
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PMID:An interaction between the pineal gland and olfactory deprivation in potentiating the effects of melatonin on gonads, accessory sex organs, and prolactin in male rats. 740 Nov 93


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