Decrease In General Activity Research Articles

Studies of learned helplessness in honey bees (Apis mellifera ligustica).

The current study reports 2 experiments investigating learned helplessness in the honey bee (Apis mellifera ligustica). In Experiment 1, we used a traditional escape method but found the bees' activity levels too high to observe changes due to treatment conditions. The bees were not able to learn in this traditional escape procedure; thus, such procedures may be inappropriate to study learned helplessness in honey bees. In Experiment 2, we used an alternative punishment, or passive avoidance, method to investigate learned helplessness. Using a master and yoked design where bees were trained as either master or yoked and tested as either master or yoked, we found that prior training with unavoidable and inescapable shock in the yoked condition interfered with avoidance and escape behavior in the later master condition. Unlike control bees, learned helplessness bees failed to restrict their movement to the safe compartment following inescapable shock. Unlike learned helplessness studies in other animals, no decrease in general activity was observed. Furthermore, we did not observe a "freezing" response to inescapable aversive stimuli-a phenomenon, thus far, consistently observed in learned helplessness tests with other species. The bees, instead, continued to move back and forth between compartments despite punishment in the incorrect compartment. These findings suggest that, although traditional escape methods may not be suitable, honey bees display learned helplessness in passive avoidance procedures. Thus, regardless of behavioral differences from other species, honey bees can be a unique invertebrate model organism for the study of learned helplessness. (PsycINFO Database Record

Some pharmacological effects of Tityus obscurus venom in rats and mice

There are a great number of studies about Brazilian scorpions. However, little is known about the venom of scorpions of northern Brazil, mainly about Tityus obscurus, which is responsible for the most number of accidents in the Amazon. Thus, this study aimed to evaluate some pharmacological effects of T. obscurus venom in rats and mice. In rats, the venom (10 mg/kg i.p.) caused hemorrhagic patches in the lung parenchyma but did not lead to pulmonary edema. There was a decrease in general activity, observed in the activity box after venom injection. The venom did not induce changes in the occurrence and intensity of experimentally induced convulsions, nor did it cause hippocampal neuronal loss. In mice, the LD50 obtained was 3.13 mg/kg (i.p.). Different doses of the venom (0.2; 1; 5; 10; 15 μg/30 μL per hind paw) induced edematogenic and moderate nociceptive activity in mice. The Tiyus serrulatus venom used as comparison caused more intense symptomatology in mice. Comparing to the venom of other Tityus scorpions of medical importance, that have convulsant and intense nociceptive effects and cause lung edema, as described in the literature, we can conclude that the venom of T. obscurus probably has different characteristics.

Age-related declines in general cognitive abilities of Balb/C mice are associated with disparities in working memory, body weight, and general activity

A defining characteristic of age-related cognitive decline is a deficit in general cognitive performance. Here we use a testing and analysis regimen that allows us to characterize the general learning abilities of young (3-5 mo old) and aged (19-21 mo old) male and female Balb/C mice. Animals' performance was assessed on a battery of seven diverse learning tasks. Aged animals exhibited deficits in five of the seven tasks and ranked significantly lower than their young counterparts in general learning abilities (aggregate performance across the battery of tasks). Aging added variability to common core performance (i.e., general learning ability), which translated into increased variability on the individual cognitive tasks. Relatedly, general learning abilities did not differ between the two ages among the best quartile of learners (i.e., cognitive abilities were spared in a subsample of the aged animals). Additionally, working memory capacity (resistance to interference) and duration (resistance to decay) accounted for significantly more of the variability in general learning abilities in aged relative to young animals. Tests of 15 noncognitive performance variables indicated that an increase in body weight (and an associated decrease in general activity) was characteristic of those aged animals which exhibited deficient general learning abilities. These results suggest the possibility that general cognitive deficits in aged animals reflect a failure of specific components of the working memory system, and may be related to variations in body weight and an associated decrease in activity.

Effects of interleukin-1β and lipopolysaccharide on behavior of mice in the elevated plus-maze and open field tests

It has been postulated that infections, inflammatory processes and resulting cytokines may be causative factors in emotional disorders, including depression and anxiety. Support for this possibility has been sought in studies of animal behavior following administration of interleukin-1 (IL-1) and lipopolysaccharide (LPS). However, such treatments induce a variety of behavioral responses, collectively known as sickness behavior, some of which could affect the performance in tests used to assess anxiety and depression. Thus the effects of peripheral administration of IL-1β and LPS on the behavior of mice were studied in the elevated plus-maze (EPM) and the open field (OF). Mouse IL-1β (30, 100, 300, and 1000 ng) was injected intraperitoneally 30 or 60 min, and LPS (0.5, 1 and 5 μg) 120 min before the tests. IL-1β and LPS induced dose-dependent decreases in open arm entries and the time spent on the open arms in the EPM, effects considered to reflect anxiety-like behavior. However, entries to all arms were also reduced in a dose-dependent manner, indicating a decrease in general activity. In the OF, IL-1β and LPS decreased the number of line crossings in the center of the field, that can also be considered to reflect anxiety-like behavior. However, this effect was accompanied by a similar decrease in line crossings in the periphery, as well as in rears and climbs. Thus the doses of IL-1β and LPS necessary to induce these effects also decreased locomotor activity in the EPM and OF. Therefore, the behavioral responses induced by IL-1β and LPS in the EPM and the OF considered to reflect anxiety must be interpreted in the light of this reduction in overall activity. Thus the results do not provide unequivocal support for the suggestion that LPS or IL-1 mediate anxiety. Nevertheless, because infections, endotoxins, and the ensuing cytokines cause alterations in CNS norepinephrine and serotonin, they may contribute to emotionality, and perhaps to anxiety.

Effects of baclofen on reserpine-induced vacuous chewing movements in mice

We have described that GABA mimetic drugs present the ability to inhibit the expression of reserpine-induced oral movements. In this respect, oral movements is associated with important neuropathologies. This study investigates the effects of an acute or a repeated treatment of different doses of the GABA B agonist baclofen, as well as withdrawal from these treatments, on the development and/or expression of reserpine-induced vacuous chewing movements (VCM). Male mice received two injections of vehicle or of 1 mg/kg reserpine separated by 48 h. In the first experiment, 24 h later, animals were acutely treated with vehicle or baclofen (1, 2 or 4 mg/kg). In the second experiment, animals were treated with vehicle or baclofen (1 or 4 mg/kg) for four consecutive days receiving a concomitant injection of 1 mg/kg reserpine (or vehicle) on Days 2 and 4. Twenty-four hours later, animals received vehicle or baclofen. Thirty minutes after the last injection, they were observed for quantification of VCM and open-field general activity. The acute administration of all the doses of baclofen abolished the manifestation of reserpine-induced VCM. Repeated treatment with 1 mg/kg baclofen induced tolerance to the ability of an acute injection of this dose to reduce VCM. Treatment with baclofen (4 mg/kg) did not modify spontaneous VCM. Acute administration of the highest dose induced a decrease in general motor activity and a potentiation of the reserpine-induced decrease in general activity. These results reinforce the involvement of GABAergic hypofunction in the expression of oral movements and suggest that a repeated treatment with baclofen induces compensatory changes in GABAergic transmission that can attenuate its acute property to decrease VCM.

Lipopolysaccharide-Induced Immunostimulation Produces A Dose- and Time-Dependent Decrease in General Activity and Weight Gain in Preweanling Rats

The immunostimulant lipopolysaccharide (LPS) produces numerous physiological and behavioral effects in adult rodents. The present study examined the effects of this endotoxin on activity levels and weight gain in 20-day-old preweanling rats. Experiment 1 demonstrated that 400 ~g/kg of LPS produced a significant decline in locomotor activity 1 hr postinjection, and both 200 ~g/kg and 400 ~g/kg significantly suppressed weight gain over the first 24 hr posttreatment. The effect on weight gain dissipated by 48 hr following LPS administration. Experiment 2 replicated the effects of 400 ~g/kg LPS on activity at 1 hr and on weight gain, and also assessed its effects upon activity level 24 hr following administration. Despite the significant decline in weight gain over the initial postinjection day, LPS animals' activity level was normal 24 hr after injection. These results indicate that the endotoxin LPS produces significant but transient decreases in both locomotor activity and weight gain in preweanling rats. The relationship of these findings to other issues involving physiology and sickness behavior is discussed.

Effects of prenatal exposure to deltamethrin on forced swimming behavior, motor activity, and striatal dopamine levels in male and female rats

The effects of prenatal exposure of rat pups to 0.08 mg/kg deltamethrin (DTM) on physical, reflex and behavioral developmental parameters, on forced swimming and open-field behaviors, and on striatal monoamine levels at 60 days of age were observed. Maternal and offspring body weight, physical and reflex development were unaffected by the exposure to the pesticide. At 21 days of age, open-field locomotion frequency and immobility duration of male and female offspring were not different between control and exposed animals. However, male rearing frequency was increased in experimental animals. A decreased immobility latency to float and in general activity after the swimming test in male offspring was observed at adult age; no interference was detected in the float duration during the swimming test. In addition, these animals presented higher striatal 3,4-dihydroxyphenylacetic acid (DOPAC) levels without modification in dopamine (DA) levels and an increased DOPAC/DA ratio. These data indicate a higher activity of the dopaminergic system in these animals. Noradrenaline (NA) levels were increased, while MHPG levels were not detectable in the system studied. Serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels, as well as the homovanillic acid (HVA)/DA ratio, were not modified by the exposure to the pesticide. No changes were observed in swimming and open-field behaviors nor were there any changes in striatal monoamines or their metabolites in the female experimental group. In relation to the pesticide formula, the present data showing that prenatal exposure to DTM alters latency to float and the activity of striatal dopaminergic system might reflect a persistent effect of the pesticide on animal motor activity, mainly in males. On the other hand, the decrease in general activity observed in experimental male rats suggests higher levels of emotionality induced by previous exposure to the swimming behavior test in relation to control animals. Data gathered in the present study may be important for the assessment of the safety of pyrethroid insecticides.

Time budget as related to feeding tactics of European polecat Mustela putorius

The time budget of five male and four female European polecats was studied in western France through radiotracking surveys. Their activity level averaged 7 h and 31 min without any significant differences between males and females. However two phases, foraging and travelling, were not similarly distributed in both sexes. Despite a strong sexual dimorphism, females spent more time foraging than males. Travelling, i.e. time devoted to linear movements was more important in males than females. Variations in activity phase duration were correlated with the proportions of food categories, suggesting that the dispersion of available resources directly influenced polecat activity. The exploitation of prey showing an aggregative distribution such as anurans led to a decrease in general activity whereas the consumption of rodents, which were more regularly distributed, was correlated to the foraging activity. Mating and breeding also affected the activity duration. Thus it seems that the time budget of polecats resulted from a compromise between social organization and trophic constraints.

Multiple effects of tetrahydroaminoacridine on the cholinergic system: Biochemical and behavioural aspects

9-Amino-1,2,3,4-tetrahydroaminoacridine (THA) in combination with lecithin has been reported to improve the memory of Alzheimer's disease patients. We have examined some properties of THA in vitro and in vivo so as to define some of the mechanism(s) by which THA might produce its therapeutic effects. In vitro, THA was more potent at inhibiting human plasma cholinesterase (IC50 = 0.03 microM) than human erythrocyte acetylcholinesterase (IC50 = 0.3 microM) and rat brain acetylcholinesterase (IC50 = 0.32 microM). Radioligand binding studies indicated that THA binds reversibly and competitively to primary M1 and M2 human cortical muscarinic receptors with similar affinities. Moreover, THA showed similar affinity for temporal cortices muscarinic receptors from Alzheimer and non-Alzheimer (control) brains. In vivo, subcutaneous administration of THA (1-8 mg/kg body weight) to adult rats (6 months old) produced a dose dependent decrease in general activity compared to saline-treated rats. However, at a concentration of 0.5 mg/kg body weight, the general activity of the rats was increased compared to saline-treated rats. The cognitive function of the THA-treated adult rats (subcutaneously 2 mg/kg body weight) was not significantly improved compared to saline-treated rats. It is concluded that the mechanisms of action of THA on the cholinergic system involve reversible inhibition of cholinesterases and reversible and competitive interaction with muscarinic acetylcholine receptors. These effects might be of therapeutic value in the treatment of Alzheimer's disease.

Endorphinergic modulation of neural reward systems indicated by behavioral changes

Experiments were performed in rats expecting and/or having received rewards to see if naloxone-antagonizable changes occur in behavior. It was found that rats expecting to receive candy display a naloxone-blockable increase in nociceptive thresholds and a naloxone-sensitive increase in rearing. Similarly, water-deprived rats expecting to receive water show a naloxone-blockade increase in rearing, whereas thirsty animals not expecting water show no changes in nociception or activity. Naloxone was also found to reduce the consumption of a highly palatable food and to diminish the performance of rats trained to wait in one place to receive candy. The latter indicates that the naloxone effect upon goal seeking is not dependent upon a decrease in general activity. Experiments in highly morphine-tolerant rats maintained on relatively constant morphine concentrations showed that these rats drink chocolate milk in the same way as placebo-treated animals. The same rats were found to fail to decrease their intake to the same extent as placebo-controls when water is substituted for the first time for chocolate milk given regularly every day. This points to the possibility that a negative action of endorphins, that is a decrease in release, decreasing consumption, upon a reduction in the palatability of an expected food, might be absent in highly tolerant animals. It is suggested that endogenous opiate(s) regulate mood as defined by the level of goal-seeking behavior, sensitivity to noxious stimuli and general activity.

MIF-1 (Pro-Leu-Gly-NH 2) decreases activity in Siamese Fighting Fish (Betta splendens)

The effects of MIF-1 (Pro-Leu-Gly-NH 2) on activity and aggression of male Siamese Fighting Fish ( Betta splendens) were considered. Animals were given intraperitoneal injections of 0.0 or 10.0 mg/kg MIF-1. After a 10-minute delay, they were placed in a 10 gallon aquarium and their activity was monitored for 60 minutes. Although aggressive responses in the presence of suitable opponents were not reliably affected, a significant decrease in general activity was produced. This is compatible with differential effects of MIF-1 across species.

Ocelli, dark adaptation and landing reaction in a flesh fly (Calliphoridae)

Abstract Previous researches have shown that in flies the landing reaction threshold is lower at lower light intensities. Since it is commonly observed that flies do not fly in darkness it has been hypothesized that the lowering of the landing reaction threshold may be due at least partly to a decrease in general activity mediated by the cervical ocelli (which are known to have a dynamogenic effect on other kinds of behaviour. The experiments done to test this hypothesis have shown: 1) the landing reaction threshold is lower at low light intensities; 2) the adaptation process to light is slower than the adaptation to “darkness”; 3) the enhanced sensitivity to movement due to increasing darkness is not affected by the light falling on the ocelli; 4) the sensitivity to movement is affected not only by the illumination of the ommatidia stimulated by the moving stimuli but also by illuminating the ommatidia not directly stimulated by the moving stimuli.

Behavioral effects of 2,5-dimethoxy-4-methylamphetamine (DOM) in rats and mice

The characteristics of the behavioral effects of 2,5-dimethoxy-4-methylamphetamine (DOM or STP) were compared with those of mescaline and methamphetamine in rats and mice. DOM significantly increased locomotor activity in an open-field situation at 0.5–1.0 mg/kg i.p., but at doses above 5 mg/kg i.p. caused biphasic changes, i.e. an initial decreased followed by an increase in motility and exploratory behavior. This hyperactivity was not accompanied by simultaneous increase in rearing. Besides, DOM induced head twitches in rats as well as in mice at doses above 0.1 mg/kg i.p., and marked backward locomotion only in rats at doses larger than 5 mg/kg i.p. The occurrence of backward locomotion might be attributable to the initial decrease in general activity. Behavioral effects of DOM were different from those of either mescaline or methamphetamine although they resembled those of mescaline in some respects.

Effect of central early postnatal 6-hydroxydopamine administration on brain catecholamines and pituitary-adrenal function in adulthood.

Central administration of 6-hydroxydopamine (6OHDA) to newborn rats induced a dose-dependent and long-lasting decrease in noradrenaline (NA) and dopamine (DA) content in adult male and female rat brain. After postnatal administration of 100 <i>µ</i>g 6OHDA, a decrease of about 50% of NA and DA content of the whole brain was found in 9- to 10-week-old rats; 200 <i>µ</i>g 6OHDA induced a reduction of 80 % of NA and DA content. The latter treatment was followed by a severe growth retardation, a marked myosis, a decrease in general activity, and disappearance of clonic convulsions after decapitation. At the same time, however, in both groups of animals no change in basal pituitary-adrenal activity was found, as evaluated by measurement of corticosterone in plasma, <i>in vitro </i>adrenal corticoid production, and adrenal weight. Apparently even severe inhibition of the development of central DA and NA systems by 6OHDA administration to the newborn rat did not induce any change in basal pituitary-adrenal functioning.

Gastric Motility in Relation to Anhydraemia.

In an attempt to throw some light on the disturbances of gastric motility occurring during the deficiency of what has been spoken of hitherto as vitamin B these experiments were undertaken. Dogs were deprived of water and parallel observations on gastric motility, and blood concentration as indicated by hemoglobin estimations, were made. Except for anorexia and decrease in general activity no abnormal symptoms were in evidence. All of the dogs developed an increase of approximately 20% in hemoglobin (estimated by the method of Cohen and Smith1) and complete gastric atony. Liberal administration of water produced a rapid decrement in blood concentration, followed by a return of gastric motility to normal within a few days. The results indicate a striking parallelism to exist between anhydraemia and gastric motility. The significance of this phenomenon in relation to disturbances of gastric motility occurring in “B”-avitaminosis will be discussed elsewhere.