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At least 1,153 records · Page 64Linked to original sources
PubMed1998

Memory and long-term potentiation (LTP) dissociated: normal spatial memory despite CA1 LTP elimination with Kv1.4 antisense.

Long-term potentiation (LTP) in the hippocampal slice preparation has been proposed as an in vitro model for long-term memory. However, correlation of LTP with memory in living animals has been difficult to demonstrate. Furthermore, in the last few years evidence has accumulated that dissociate the two. Because potassium channels might determine the weight of synapses in networks, we studied the role of Kv1.4, a presynaptic A-type voltage-dependent K+ channel, in both memory and LTP. Reverse transcription-PCR and Western blot analysis with specific antibodies showed that antisense oligodeoxyribonucleotide to Kv1.4 microinjected intraventricularly into rat brains obstructed hippocampal Kv1.4 mRNA, "knocking down" the protein in the hippocampus. This antisense knockdown had no effect on rat spatial maze learning, memory, or exploratory behavior, but eliminated both early- and late-phase LTP and reduced paired-pulse facilitation (a presynaptic effect) in CA1 pyramidal neurons without affecting dentate gyrus LTP. This presynaptic Kv1.4 knockdown together with previous postsynaptic Kv1.1 knockdown demonstrates that CA1 LTP is neither necessary nor sufficient for rat spatial memory.

Animals↗
PubMed2001

CNS active potentials of some Hypericum species of India.

Hypericum is a large genus comprising 200 species, wide spread on temperate region and tropical mountains. Several different species are available in Indian subcontinent. Psychopharmacological profiles of the two different Hypericum species e.g., H. hookerianum and H. patulum available in Nilgiris, India were investigated at two different doses (200 and 400 mg/kg, p.o.) in different animal models viz. Spontaneous motor activity (SMA) test in mice; Exploratory behaviour test by Head dip test in mice and Y-maze test in rats; Effects on pentobarbitone induced sleeping time in mice and study of the effects on body temperature in rats. All the extracts tested showed enhancement in spontaneous motor activity (SMA) in mice and exploratory behavior by head dip test in mice and Y-maze test in rats. The extracts reduce significantly the pentobarbitone induced sleeping time in mice. When tested for their effect on body temperature in rats, the extract of H. hookerianum showed significant reduction in yeast induced pyrexia with no effect on normal body temperature, while H. patulum showed no activity in this experimental model.

Animals↗
PubMed2001

Evaluation of psychopharmacological effects of Clerodendrum phlomidis Linn. extract.

The methanolic extract of Clerodendrum phlomidis Linn. (MECP) leaves was evaluated for its psychopharmacological activities in several experimental models using Swiss albino mice and Wistar albino rats. The MECP was found to cause significant reduction in spontaneous activity, and decreases in exploratory behavioral profiles by the Y-maze and head dip test. It also showed reduction in muscle relaxant activity by rotarod, 30 degrees inclined screen and traction tests, as well as significantly potentiated the phenobarbitone sodium-induced sleeping time in the doses examined (200, 400 and 600 mg/kg body wt.). All the results were compared with respective controls for the evaluation of significance.

Acacia↗
PubMed1982

Chronic cadmium exposure: relation to male reproductive toxicity and subsequent fetal outcome.

Acute injections of high doses of Cd induce marked testicular necrosis. However, the effects of low-dose, oral Cd exposure on a chronic basis are not well documented. The present investigation was designed to examine the effects of such exposure as reflected in parameters of spermatotoxicity and histology. Moreover, the impact on fetal outcome was measured by evaluating teratological and postnatal neurobehavior endpoints. Male Long-Evans hooded rats (100 d of age) were exposed to 0, 17.2, 34.4, or 68.8 ppm Cd for 70 d. During this period, the animals were maintained on a semipurified diet to control for the contributions of Zn and other trace elements. Near the end of exposure the males were mated to three female rats. One was sacrificed on d 21 of pregnancy for teratological assessment, including fetal weight, and determination of preimplantation and postimplantation loss. The other two dams were allowed to deliver, and their offspring were tested on tasks of exploratory behavior (d 21) and learning (d 90). Subsequently, the male parent was sacrificed and a variety of measures recorded including weights of testes and caudae epididymides, sperm count and sperm morphology, and Cd content of liver and kidney. One of the testes was also evaluated histologically. No significant effects were observed on any of the parameters of reproductive toxicity or fetal outcome. These findings suggest that, at the doses employed in this study, Cd did not have significant deleterious effects on the male reproductive system. Morever, the traditional view of Cd-related testicular insult, based on acute exposure, injection protocols, needs to be reevaluated in terms of environmental relevance.

Analysis of Variance↗
PubMed2006

Virtual and physical toys: open-ended features for non-formal learning.

This paper examines the integrated toy--both physical and virtual--as an essential resource for collaborative learning. This learning incorporates rehabilitation, training, and education. The data derived from two different cases. Pedagogical issues related to non-formal learning and open-ended features of design are discussed. Findings suggest that social, material, and expressive affordances constitute a base for an alterative interface to encourage children's play and learning.

Child↗
PubMedDate not supplied

Saccharin drinking rather than open field behaviour predicts initial ethanol acceptance in Wistar rats.

This study examined the relationship between saccharin drinking, open field behaviour and ethanol drinking in Wistar rats. Correlational analysis revealed that both absolute saccharin drinking and an increase in total fluid intake in the presence of saccharin positively correlated with the initial acceptance of increasing ethanol concentrations in a two-bottle choice situation (2-8% v/v ethanol vs water). This relationship disappeared, however, during further weeks of ethanol drinking when ethanol was available in a three-bottle choice situation (8% ethanol vs 16% ethanol vs water). In contrast, none of the behavioural parameters measured in the open field test (forward locomotion, rearings, central entries, time in central area) correlated with subsequent ethanol consumption. These results indicate that saccharin drinking, rather than open field parameters, may predict subsequent ethanol intake during the initial period of exposure to low ethanol concentrations.

Alcohol Drinking↗
PubMed2000

Effect of ultraviolet radiation on the performance of intact male turkeys.

Ultraviolet (UV) sensitivity in birds has been shown to be intrinsically involved in the selection of mates; UV may, therefore, also play a role in the establishment and maintenance of social hierarchies in intensively housed turkeys. Cereal seeds and straw are known to reflect UV, and turkeys may use these cues for foraging and exploratory behaviors. A series of trials was conducted to see if supplementation of the photoperiod (12 h at various white light intensities) with UV radiation (0.06 to 0.16 W/m2 at floor level) and regular supplies of straw to the litter allow a better recognition of individuals within a flock, enrich the environment by the provision of new pecking material and of radiation across the whole range of avian sensitivity, and, as a consequence, reduce the incidence of injurious pecking in male turkeys that have not been beak-trimmed, detoed, or desnooded. Body weight gain, feed intake, feed conversion efficiency, and leg integrity were generally not significantly affected by UV supplementation and environmental enrichment. In contrast, the provision of UV radiation, simultaneous with a 12-h photoperiod of white light at intensities of <70 lx to 5 wk and of 10 lx to 20 wk, and the regular addition of straw to the litter, significantly reduced the incidence of culling because of injurious pecking. However, complex interactions among UV supplementation, white light intensity, and material environmental enrichment precluded a simple recommendation to solve the problem of injurious pecking.

Animal Nutritional Physiological Phenomena↗
PubMed1983

Developmental implications of clinically applied vestibular stimulation.

Recent research has promoted the development of several techniques that use various forms of sensory stimulation to improve the neuromotor development of high-risk infants and developmentally delayed children. One of the newest and most popular adjuncts to therapy for developmentally delayed children is vestibular stimulation. The applied clinical research using vestibular stimulation activities with healthy human infants, infants at risk, and young children with developmental delay disorders is reviewed. The literature discussed indicates that controlled vestibular stimulation has had positive effects on arousal level, visual exploratory behavior, motor development, and reflex integration. Also discussed is the need for continued applied clinical research to further substantiate the most effective type of vestibular stimulation and the population for which such stimulation is most beneficial.

Cerebral Palsy↗
PubMed1987

Ketanserin pretreatment reverses alfentanil-induced muscle rigidity.

Systemic pretreatment with ketanserin, a relatively specific type-2 serotonin receptor antagonist, significantly attenuated the muscle rigidity produced in rats by the potent short-acting opiate agonist alfentanil. Following placement of subcutaneous electrodes in each animal's left gastrocnemius muscle, rigidity was assessed by analyzing root-mean-square electromyographic activity. Intraperitoneal ketanserin administration at doses of 0.63 and 2.5 mg/kg prevented the alfentanil-induced increase in electromyographic activity compared with animals pretreated with saline. Chlordiazepoxide at doses up to 10 mg/kg failed to significantly influence the rigidity produced by alfentanil. Despite the absence of rigidity, animals that received ketanserin (greater than 0.31 mg/kg i.p.) followed by alfentanil were motionless, flaccid, and less responsive to external stimuli than were animals receiving alfentanil alone. Rats that received ketanserin and alfentanil exhibited less rearing and exploratory behavior at the end of the 60-min recording period than did animals that received ketanserin alone. These results, in combination with previous work, suggest that muscle rigidity, a clinically relevant side-effect of parenteral narcotic administration, may be partly mediated via serotonergic pathways. Pretreatment with type-2 serotonin antagonists may be clinically useful in attenuating opiate-induced rigidity, although further studies will be necessary to assess the interaction of possibly enhanced CNS, cardiovascular, and respiratory depression.

Adjuvants, Anesthesia↗
PubMed1998

Regulation of attention to novel stimuli by frontal lobes: an event-related potential study.

This study examined the relationship between orienting responses to novel events and subsequent exploratory behavior. The N2-P3 electrophysiologic component of the orienting response was found to be larger for novel than repetitive background stimuli. Across subjects, the amplitude of this N2-P3 response in frontal regions strongly predicted the proportional increase in the duration of viewing directed toward novel compared to background stimuli. Within subjects, larger N2-P3 amplitudes in response to novel stimuli were associated with longer viewing durations on those stimuli. These results suggest that the N2-P3 component of the orienting response reflects the activity of a neural system involving frontal networks that dynamically regulates the subsequent allocation of attentional resources to novel stimuli.

Adult↗
PubMed1999

Propionyl-IIGL tetrapeptide antagonizes beta-amyloid excitotoxicity in rat nucleus basalis.

A putative tetrapeptide beta-amyloid (Abeta) antagonist (propionyl-Ile-Ile-Gly-Leu [Pr-IIGL]) based on the [31-34] sequence of Abeta was previously shown to rescue astrocytes from Abeta-induced membrane depolarization and subsequent long-term elevations of the intracellular Ca2+ concentration in vitro. Here we provide in vivo evidence that the Pr-IIGL tetrapeptide effectively attenuates the excitotoxic action of Abeta(1-42) on cholinergic neurons of the rat magnocellular nucleus basalis (MBN). We also demonstrate by means of microdialysis that administration of Pr-IIGL abolished Abeta(1-42)-induced increases in extracellular aspartate and glutamate concentrations in the MBN, which coincide with a significant preservation of cholinergic MBN neurons and their cortical projections. This neuroprotective effect was associated with preserved exploratory behavior in an open-field paradigm, and improved memory retention in a step-through passive avoidance task. Our data presented here indicate for the first time the efficacy of short, modified functional Abeta antagonists in ameliorating Abeta excitotoxicity in vivo.

Acetylcholinesterase↗
PubMed1993

Infections in day care.

The number of preschool-aged children who attend day care has increased dramatically in recent years. Factors promoting spread of infections in this setting include crowding, lack of hygiene, high prevalence of early exploratory behaviors, and the likelihood of many susceptible children being in close contact. As a result, children attending day care experience a great number of episodes of respiratory and gastrointestinal illness than do other children. Moreover, the risk of a number of specific infections, including Haemophilus influenzae type b and hepatitis A, is increased by attendance in day care. Day-care staff are at increased risk of a number of infections, some of which, including cytomegalovirus and parvovirus B19, may have adverse consequences to a fetus. The presence of children in day care increases the risk of illness among staff and family members and may promote the circulation of infections in the community as a whole.

Adult↗
PubMed2005

Vibrational communication facilitates cooperative foraging in a phloem-feeding insect.

Insects are the dominant herbivores in tropical forests, with a range of mechanisms for exploiting plant resources. For group-living species, such mechanisms may involve communication. The Neotropical treehopper Calloconophora pinguis (Hemiptera: Membracidae) is a sap-feeding species in which groups of siblings feed on new leaves during the brief period of leaf expansion. Using an experimental approach, a process of cooperative foraging among siblings was documented, in which a few individuals in a group behave as scouts, locating a new feeding site and advertising it using plant-borne vibrational signals. Signalling leads to a period of positive feedback in which newly recruited individuals signal in concert with those already there. The food signalling system of C. pinguis is unique in its use of synchronized group displays and in the tight coordination of receiver responses with collective signals. Examples from a number of taxonomic groups show that vibrational communication can allow group-living insects to solve the challenges of feeding on plants, such as remaining in a foraging group or avoiding predation. While most research has focused on leaf-feeding species, sap-feeding species may remove just as much biomass. This study shows that cooperative vibrational communication underlies the ability of a sap-feeding species to exploit plant resources during a narrow window of availability.

Analysis of Variance↗
PubMedDate not supplied

Brief theta-burst stimulation induces a transcription-dependent late phase of LTP requiring cAMP in area CA1 of the mouse hippocampus.

Memory storage in the mammalian brain can be divided into a short-term phase that is independent of new protein synthesis and a long-term phase that requires synthesis of new RNA and proteins. A cellular model for these two phases has emerged from studies of long-term potentiation (LTP) in the three major excitatory synaptic pathways in the hippocampus. One especially effective protocol for inducing robust and persistent LTP is "theta-burst" stimulation, which is designed to mimic the firing patterns of hippocampal neurons recorded during exploratory behavior in intact awake animals. Unlike LTP induced by non-theta tetanization regimens, little is known about the biochemical mechanisms underlying theta-burst LTP in the hippocampus. In the present study, we examined theta-burst LTP in the Schaffer collateral pathway. We found that 3 sec of theta-burst stimulation induced a robust and persistent potentiation (theta L-LTP) in mouse hippocampal slices. This theta L-LTP was dependent on NMDA receptor activation. The initial or early phase of theta-LTP did not require either protein or RNA synthesis and was independent of cAMP-dependent protein kinase (PKA) activation. In contrast, the late phase of theta-LTP required synthesis of proteins and RNA and was blocked by inhibitors of PKA. Prior induction of theta-LTP also occluded the potentiation elicited by chemical activation of PKA. Our results show that, like non-theta LTP, theta-induced LTP in area CA1 of the mouse hippocampus also involves transcription, translation, and PKA and suggest that cAMP-mediated gene transcription may be a common mechanism responsible for the late phases of LTP induced by both theta and non-theta patterns of stimulation.

Animals↗
PubMed1979

Three social-preference measures in PKU monkeys.

Of twenty-four one-year-old rhesus, half were brain damaged from excessive phenylalanine (PKU) administered either pre- or post-natally. When compared on three measures of affiliation--(a) a simultaneous forced-choice proximity circus test, (b) a sequential free-operant Butler-box test, and (c) a social group in a playroom--the duration measure of the circus gave the best differentiation between stimulus animals, the Butler box the poorest. Both types of PKU monkeys were found to strongly prefer familiar PKU monkeys, and controls to refer unfamiliar followed by familiar controls. This extends preference research to induced brain damage and confirms behavioural abnormality in PKU macaques, an abnormality detectable by both humans and other monkeys.

Animals↗