Stress, behavioral arousal, and open field activity—A reexamination of emotionality in the rat

The effects of stress upon emotionality, and of emotionality upon the open field activity of rats have now been studied for over four decades. Controversy remains however regarding the degree to which stress alters behavior, and the direction of that change. One reason for this is the absence of an adequate behavioral definition of stress. The present series of experiments demonstrates a standard relatively nontraumatic stress induction procedure which may be used in conjunction with open field testing. Pre-exposure to moderately intense light and white noise facilitated open field activity as measured by initial activity, lowered defecation scores, and supplementary measures (rearing, grooming, center field penetration). Further parametric, psychoendocrine, and pharmacological studies characterized the nature of the facilitation, its time course, and its modification by other manipulations. Our results suggest the initial behavioral response to stress in an open field is activation. Previous studies may have differed in their results relating stress and behavior because of subtle procedural distinctions, some of which may be identified using the present technique.     

Chlordiazepoxide effects on reactions to novelty and activity with and without prior drug experience

Reactions to novelty, rearing and ambulation were observed in rats following saline or chlordiazepoxide injections either with or without prior drug experience. Drug suppression of the former two response was evident but there was no indication of prior drug experience being effective. However, experience appeared to negate the compound's depressant effect on ambulation shown by inexperienced subjects. It was concluded that inhibitory influences of chlordiazepoxide on reactions to novelty and rearing can not be ascribed to the aversive effects of a novel drug state.This work was supported by University of Canterbury Research Grant No. C71/52.     

家蝇室内种群产卵动态观察

目的观察家蝇室内种群在整个产卵期内的产卵量动态变化规律。方法观察家蝇室内种群第3代及第4代成虫整个产卵期内的每天的产卵量,并进行分析。结果第3代成虫于产卵期第7天达产卵高峰,前10天产卵量相对较高,产卵期后期产卵量稳定在较低水平;第4代成虫于产卵期第4天出现产卵高峰,前7天产卵较多,后期产卵相对较少。结论家蝇室内种群产卵主要集中在产卵期前期,后期产卵能力较低,产卵量较少。     

Combined effects of chlordiazepoxide treatment and food deprivation on concurrent measures of feeding and activity

The effects of chlordiazepoxide (CDP-0, 5, 10 mg/kg) on feeding, rearing, and ambulatory locomotion of male Holtzman rats were investigated in an open-field arena under 3 different conditions of food deprivation (0, 24, 48 hr). Both CDP and food deprivation enhanced feeding, with their combined effects being essentially additive. Also, CDP significantly decreased both rearing and ambulatory locomotion, although this effect tended to be counteracted by increases in food deprivation. The interrelationship (correlation) of the behavioral effects of CDP suggested that the reduction in activity measures is due, in part, to the competing or incompatible nature of feeding and that rearing and ambulatory locomotion are somewhat redundant measures of activity under the present conditions.     

Dopamine-sensitive alternation and collateral behaviour in a Y-maze: Effects of d-amphetamine and haloperidol

The degree of alternation of arm choice in a Y-maze was examined on 15-min tests over 4 days in rats treated (IP) with saline, amphetamine (0.5 or 2.0 mg/kg) or pretreated with haloperidol (0.08 mg/kg) in each condition prior to test. On day 1 amphetamine-treated animals chose arms at random, but from day 2–4 those receiving the higher dose perseverated their choice. Controls maintained alternation. These effects could be prevented by haloperidol pretreatment. Amphetamine treatment increased the frequency of rearing at the middle, choice-point of the maze more than at the end of an arm. The increase at the mid-point was suppressed by haloperidol pretreatment from day 1 and at the end of an arm from day 2. Amphetamine induced an increase in head-turning/looking that was suppressed by haloperidol from day 2. The effect of haloperidol in increasing the duration of an item of looking or rearing at the end of an arm also started later in testing. Two effects are postulated to have occurred: (i) a conflict on day 1 between novelty-controlled sensory or attentional effects that leads to an alternation of arm choice and amphetamine-induced dopaminergic activity that facilitates an alternation of behavioural responses. The result was random choice and increased rearing at the choice point. (ii) On days 2–4 the drug-induced effects on switching motor responses came to control behaviour.     

Dyphenylhydantoin enhancement of diazepam effects on locomotor activity in mice

The interaction of diazepam and diphenylhydantoin on locomotor activity and rearing behavior was studied in mice. Pretreatment of mice with diphenylhydantoin (4.0 and 8.0 mg/kg) significantly reversed the stimulatory effects of low doses of diazepam and considerably increased the depressant effects of the benzodiazepine on locomotor activity and rearing. Neither diazepam (up to 4.0 mg/kg), diphenylhydantoin (8.0 mg/kg) alone, nor combined treatment with both drugs affected brain GABA levels and glutamic acid decarboxylase (GAD) activity at any dosage used. The present behavioral and biochemical data suggests that some of the pharmacological effects of diazepam need not be related to GABAergic mechanisms.     

Sex-dependent biological changes following prenatal nicotine exposure in the rat

Nicotine was administered to adult female rats in drinking water starting 6 weeks before mating and continuing throughout pregnancy. The litters were cross-fostered to control dams at birth. Prenatal nicotine treatment reduced both the number of male rats born and the male birth weight. Female offspring were not significantly affected. Rearing activity was reduced in male but not female offspring either when tested over a 24 hour period in a home cage environment or during a 10 minute exposure in an open field. Horizontal locomotor activity was reduced only during the first 5 minutes in the open field and again the effect was found only in the males. Baseline plasma corticosterone levels were reduced in both male and female offspring but there was no effect on stress-elevated corticosterone levels.     

Locomotor activity following intra-accumbens microinjections of dopamine D1 agonist SK&F 38393 in rats

The present study examined the effects of the dopamine D₁ receptor subtypes agonist SK&F 38393 on locomotor activities after bilateral microinjection (0.00, 0.01, 0.1, 10.0 μg) into the nucleus accumbens (Acb). The dose of 0.1 μg elicited the highest response rate across measures of locomotion, rearing and stereotypy behavior. On the other hand, the largest dose of 10.0 μg was associated with significant increase in center time behaviors. The data were supportive of the hypothesis that dose-related locomotor activities elicited by microinjections of SK&F 38393 into the Acb are independently mediated by D₁ receptors. © 1993 Wiley-Liss, Inc.     

Creutzfeldt-Jakob disease and sheep brain a report from central and southern Italy

The places of origin of 7 out of 8 patients with CJD coincide with the distribution of sheep-rearing in central and southern Italy, confirming the suggested link between this disease and eating and-or handling sheep CNS tissue. Since 6 of the 8 cases were women, it seems more likely that the virus responsible for CJD enters the body through a break in the skin of the hands and forearms in the process of foodhandling rather than via the Digestive tract. This aspect should be borne in mind when investigating the problems of CJD transmission.

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Sommario è stata studiata la distribuzione geografica dei luoghi di origine di 8 pazienti con CJD correlandola alla distribuzione, all'interno delle diverse regioni dell'Italia Centrale, e in parte Meridionale, delle aree a prevalente economia da pascolo, soprattutto pastorizia ovina. Si è indagata una eventuale connessione tra abitudini alimentari che comprendono la manipolazione a scopo alimentare ed il susseguente consumo di tessuti del SNC di ovini e la insorgenza della CJD. Viene avanzata la ipotesi che attraverso soluzioni di continuo nel rivestimento dei tegumenti delle estremità superiori, piuttosto che per la via della ingestione, l'agente virale della malattia potrebbe penetrare nell'organismo, per cui questo elemento sarebbe da tenere presente nell'affrontare i problemi connessi con le modalità di trasmissione della CJD.

     

Effects of lithium on open field behavior in “stressed” and “unstressed” rats

Rats were tested for 3 min per day, for 4 successive days, in an open field apparatus, 20 min after injection of either lithium chloride (2 mEq/kg) or physiological saline. In the first experiment, the open field was illuminated with moderate white light for some rats (stress condition) and dim red light for others (non-stress condition). In the second experiment, some rats received an electric foot shock 5 h before each open field test (stress condition) and others received no foot shock (non-stress condition). In both experiments, lithium significantly reduced rearing behavior in the stressed, but not the unstressed, rats. Lithium also reduced horizontal locomotion, but this effect appeared in both stressed and unstressed rats. In the second experiment, defecation was measured, and it was found that lithium-treated rats defecated less than saline-treated rats in the first session, but not in subsequent sessions, due to habituation which occurred for the saline rats.