Significant Increase In Locomotion Research Articles

Quantifying Acute Behavioral Reactions of Bali Mynas (Leucopsar rothschildi) to Environmental and Progressively Challenging Enrichment

Animals use specific behaviors and skills to overcome challenges and access resources. Environmental enrichment is provided to animals in human care to both promote species-appropriate behaviors and reduce undesired behaviors. Feather pecking in birds is an undesired behavior without a clear cause. The Saint Louis Zoo houses three pairs of young Bali mynas (Leucopsar rothschildi) who pluck neck feathers from conspecifics. To reduce this behavior, animal care staff presented the birds with seven enrichment items from four categories, presenting each item twice. The enrichment included a modifiable, progressively challenging bamboo tube device at multiple levels of difficulty. While plucking was not affected by any enrichment item, we observed significant increases in locomotion and decreases in autopreening, allogrooming, and head bobbing. Leafy greens produced the greatest changes when compared to other enrichment types. Overall engagement with the progressively challenging enrichment increased with the change from the first to the second level of difficulty, and interaction with the device was highest for the third and most difficult version. These increases suggest that no habituation to the progressively challenging device occurred, while a possible neophobic effect declined with multiple uses and increased familiarity.

Behavioral Effects of Vaporized Delta-8 Tetrahydrocannabinol, Cannabidiol, and Mixtures in Male Rats.

Background: The popularity of delta-8 tetrahydrocannabinol (THC) and cannabidiol (CBD) products has seen a sharp increase in use during recent years. Despite the rise in use of these minor cannabinoids, there are little to no pre-clinical behavioral data on their effects, with most pre-clinical cannabis research focusing on the behavioral effects of delta-9 THC. The current experiments aimed to characterize the behavioral effects of delta-8 THC, CBD, and mixtures of these two drugs using a whole-body vapor exposure route of administration in male rats. Methods: Rats were exposed to vapor that contained different concentrations of delta-8 THC, CBD, or CBD/delta-8 THC mixtures during 10 min of exposure. Following 10 min of vapor exposure, locomotor behavior was monitored, or the warm-water tail withdrawal assay was conducted to measure the acute analgesic effects of the vapor exposure. Results: CBD and CBD/delta-8 THC mixtures resulted in a significant increase in locomotion across the entire session. Although delta-8 THC alone had no significant effect on locomotion across the session, the 10 mg concentration of delta-8 THC had a hyperlocomotion effect in the first 30 min of the session followed by a hypolocomotor effect later in the session. In the tail withdrawal assay, a 3/1 mixture of CBD/delta-8 THC resulted in an immediate analgesic effect compared to vehicle vapor. Finally, immediately following vapor exposure, all drugs had a hypothermic effect on body temperature compared to vehicle. Conclusion: This experiment is the first to characterize the behavioral effects of vaporized delta-8 THC, CBD, and CBD/delta-8 THC in male rats. While data were generally congruent with previous research investigating delta-9 THC, future studies should explore abuse liability and validate plasma blood concentrations of these drugs following administration through whole-body vapor exposure.

Unfolding of spatial representation at systems level in infant rats.

Spatial representations enable navigation from early life on. However, the brain regions essential to form spatial representations, like the hippocampus, are considered functionally immature before weaning. Here, we examined the formation of representations of space in rat pups on postnatal day (PD) 16, using a simple habituation paradigm where the pups were exposed to an arena on three occasions, separated by ~140 min. Whereas on the first two occasions the arena was the same, on the third "test" occasion either proximal cues (Prox group), or distal cues (Dist group), or proximal and distal cues (Prox-Dist group), or no cues (No-change group) were rearranged. Locomotion (distance traveled) was used as behavioral measure of habituation, and c-Fos expression to measure regional brain activity at test. Locomotion generally decreased across the first two occasions. At test, it reached a minimum in the No-change group, indicating familiarity with the spatial conditions. By contrast, the Prox-Dist group displayed a significant increase in locomotion which was less robust in the Prox group and absent in the Dist group, a pattern suggesting that the pups relied more on proximal than distal cues during spatial exploration. c-Fos activity in the No-change group was significantly suppressed in the hippocampus (CA1, CA3, dentate gyrus) but simultaneously enhanced in the prelimbic area (PL) of the medial prefrontal cortex, compared with untreated Home-cage controls, pointing to a possible involvement of the PL in regulating locomotion in familiar spaces. By contrast, in both Prox-Dist and Prox groups c-Fos activity was enhanced in hippocampal CA1 and CA3 regions, suggesting these regions might be particularly involved in regulating exploration of spatial novelty. Our findings show that functional representations of space at a systems level are formed already in pre-weanling rats.

Increased novelty-induced locomotion, sensitivity to amphetamine, and extracellular dopamine in striatum of Zdhhc15-deficient mice

Novelty-seeking behaviors and impulsivity are personality traits associated with several psychiatric illnesses including attention deficits hyperactivity disorders. The underlying neural mechanisms remain poorly understood. We produced and characterized a line of knockout mice for zdhhc15, which encodes a neural palmitoyltransferase. Genetic defects of zdhhc15 were implicated in intellectual disability and behavioral anomalies in humans. Zdhhc15-KO mice showed normal spatial learning and working memory but exhibited a significant increase in novelty-induced locomotion in open field. Striatal dopamine content was reduced but extracellular dopamine levels were increased during the habituation phase to a novel environment. Administration of amphetamine and methylphenidate resulted in a significant increase in locomotion and extracellular dopamine levels in the ventral striatum of mutant mice compared to controls. Number and projections of dopaminergic neurons in the nigrostriatal and mesolimbic pathways were normal. No significant change in the basal palmitoylation of known ZDHHC15 substrates including DAT was detected in striatum of zdhhc15 KO mice using an acyl-biotin exchange assay. These results support that a transient, reversible, and novelty-induced elevation of extracellular dopamine in ventral striatum contributes to novelty-seeking behaviors in rodents and implicate ZDHHC15-mediated palmitoylation as a novel regulatory mechanism of dopamine in the striatum.

Vulnerability to ethanol sensitization predicts higher intake and motivation to self-administer ethanol: Proof of the incentive salience sensitization theory?

Ethanol-induced behavioral sensitization (EIBS) is thought to play a key role in addiction. However, whether EIBS is linked to an increase in the motivation to self-administerethanol in an operant paradigm has never been demonstrated, and thus, the motivational sensitization theory (increase in drug wanting) has not been yet confirmed. We investigated using the operant ethanol self-administrationparadigm if the motivation to self-administerethanol (breakpoint) is increased in female mice prone to develop EIBS. Outbred female Swiss mice were treated once a day with 2.5-g ethanol per kilogram during 10 days and challenged with the same dose of ethanol 7 days later. EIBS-pronegroup was characterized by a significant increase in locomotion between the challenge day and day 1. When the difference was not significant, mice were considered as the "EIBS-resistant"group. Mice were then trained to nose poke for a 20% ethanol solution reinforcer under a FR1 and then a FR-2schedule of reinforcement. Motivation was assessed more directly with a progressive ratio schedule. Our results show that there is a positive correlation between EIBS and both the level of intake and motivation. Interestingly, acquisition of ethanol self-administrationwas faster in sensitized mice that also display a quick and long-lastingincrease in ethanol intake together with a lack of effect of alcohol challenge on c-Fosexpression restricted to the dorsolateral striatum. These results further support that EIBS vulnerability is crucial in the development of addictive behaviors and suggest a potential link with habit learning processes.

Impact of anger emotional stress before pregnancy on adult male offspring.

Previous studies have reported that maternal chronic stress or depression is linked to an increased risk of affective disorders in progeny. However, the impact of maternal chronic stress before pregnancy on the progeny of animal models is unknown. We investigated the behaviors and the neurobiology of 60-day-old male offspring of female rats subjected to 21 days of resident-intruder stress before pregnancy. An anger stressed parental rat model was established using the resident-intruder paradigm and it was evaluated using behavioral tests. Anger stressed maternal rats showed a significant increase in locomotion and aggression but a reduction in sucrose preference. Offspring subjected to pre-gestational anger stress displayed enhanced aggressive behaviors, reduced anxiety, and sucrose preference. Further, offspring subjected to pre-gestational stress showed significant impairments in the recognition index (RI) on the object recognition test and the number of platform crossings in the Morris water maze test. The monoaminergic system was significantly altered in pre-gestationally stressed offspring, and the expression of phosphorylated cyclic adenosine monophosphate response element binding protein (P-CREB), brain-derived neurotrophic factor (BDNF), and serotonin transporter (SERT) levels in pre-gestational stressed offspring were altered in some brain regions. Fluoxetine was used to treat pre-gestational stressed maternal rats and it significantly reduced the changes caused by stress, as evidenced by both behaviors and neural biochemical indexes in the offspring in some but not all cases. These findings suggest that anger stress before pregnancy could induce aggressive behaviors, cognitive deficits, and neurobiological alterations in offspring.

Cocaine and Caffeine Effects on the Conditioned Place Preference Test: Concomitant Changes on Early Genes within the Mouse Prefrontal Cortex and Nucleus Accumbens.

Caffeine is the world's most popular psychostimulant and is frequently used as an active adulterant in many illicit drugs including cocaine. Previous studies have shown that caffeine can potentiate the stimulant effects of cocaine and cocaine-induced drug seeking behavior. However, little is known about the effects of this drug combination on reward-related learning, a key process in the maintenance of addiction and vulnerability to relapse. The goal of the present study was thus to determine caffeine and cocaine combined effects on the Conditioned Place Preference (CPP) test and to determine potential differential mRNA expression in the Nucleus Accumbens (NAc) and medial prefrontal cortex (mPFC) of immediate-early genes (IEGs) as well as dopamine and adenosine receptor subunits. Mice were treated with caffeine (5 mg/kg, CAF), cocaine (10 mg/kg, COC), or their combination (caffeine 5 mg/kg + cocaine 10 mg/kg, CAF-COC) and trained in the CPP test or treated with repeated injections inside the home cage. NAc and mPFC tissues were dissected immediately after the CPP test, after a single conditioning session or following psychostimulant injection in the home cage for mRNA expression analysis. CAF-COC induced a marked change of preference to the drug conditioned side of the CPP and a significant increase in locomotion compared to COC. Gene expression analysis after CPP test revealed specific up-regulation in the CAF-COC group of Drd1a, cFos, and FosB in the NAc, and cFos, Egr1, and Npas4 in the mPFC. Importantly, none of these changes were observed when animals received same treatments in their home cage. With a single conditioning session, we found similar effects in both CAF and CAF-COC groups: increased Drd1a and decreased cFos in the NAc, and increased expression of Drd1a and Drd2, in the mPFC. Interestingly, we found that cFos and Npas4 gene expression were increased only in the mPFC of the CAF-COC. Our study provides evidence that caffeine acting as an adulterant could potentiate reward-associated memories elicited by cocaine. This is associated with specific changes in IEGs expression that were observed almost exclusively in mice that received the combination of both psychostimulants in the context of CPP memory encoding and retrieval. Our results highlight the potential relevance of caffeine in the maintenance of cocaine addiction which might be mediated by modifying neural plasticity mechanisms that strengthen learning of the association between drug and environment.

2217

OBJECTIVES/SPECIFIC AIMS: Retinitis pigmentosa (RP) is a hereditary retinal degeneration disease that affects ~1 in 4000 individuals globally, and there are currently no effective treatment options available. In order to identify potential drug treatments, we optimized our existing a behavioral assay around a transgenic zebrafish carrying a truncated human rhodopsin transgene [Tg(rho:Hsa.RH1_Q344X)]. This line was also crossed with the Tg(-3.7rho:EGFP) reporter for rod visualization. The Q344X larvae experiences significant rod photoreceptor death by 7 days postfertilization (dpf) (Nakao et al., 2012). METHODS/STUDY POPULATION: To assess the vision of the Q344X zebrafish, the VMR assay was run under a dim-light condition based on recorded rod b-waves in larval fish (Moyano et al., 2013) and the minimum cone activation threshold in mice (Cachafeiro et al., 2010). Specifically, Q344X and control larvae at 7 dpf were placed into a 96-well plate and acclimated to a dim-light source (1.802e-05 μ W/cm2 at 500 nm) for 1 hour. The VMR was tracked and quantified during light offset. The total distance traveled was averaged and analyzed at 1 second poststimulus. Retinas were dissected from Q344X and control larvae and whole-mounted to validate the rod degeneration in the Q344X model. RESULTS/ANTICIPATED RESULTS: We found that the Q344X larvae displayed an attenuated VMR (0.121±0.041 cm) to the dim-light offset as compared with the control larvae (0.2751±0.038 cm) (two-sample t-test; p-value=4.619e-14, n=19). Analysis of whole-mounted retinae indicated significant rod degeneration at 7 dpf compared with controls (control: 87 rods/retina, Q344X: 9.3 rods/retina, Welch two-sample t-test, p-value=1.4e4). It is unlikely that the cones of the zebrafish contributed to this VMR since the light intensity of the assay was below the cone detection threshold of mice. As the only apparent difference between the 2 groups of larvae is significant rod degeneration, it can be concluded that the behavioral phenotype was a result of the degeneration. DISCUSSION/SIGNIFICANCE OF IMPACT: These results suggest that the attenuated Q344X VMR is a result of the rod photoreceptor death. This behavioral phenotype can be taken advantage of to develop a drug screening assay. Future steps will screen chemical libraries to identify compounds that ameliorate the rod degeneration. Compounds that prevent degeneration are expected to result in a significant increase in locomotion in response to the dim visual stimulus.

The Nicotine-Evoked Locomotor Response: A Behavioral Paradigm for Toxicity Screening in Zebrafish (Danio rerio) Embryos and Eleutheroembryos Exposed to Methylmercury.

This study is an adaptation of the nicotine-evoked locomotor response (NLR) assay, which was originally utilized for phenotype-based neurotoxicity screening in zebrafish embryos. Zebrafish embryos do not exhibit spontaneous swimming until roughly 4 days post-fertilization (dpf), however, a robust swimming response can be induced as early as 36 hours post-fertilization (hpf) by means of acute nicotine exposure (30–240μM). Here, the NLR was tested as a tool for early detection of locomotor phenotypes in 36, 48 and 72 hpf mutant zebrafish embryos of the non-touch-responsive maco strain; this assay successfully discriminated mutant embryos from their non-mutant siblings. Then, methylmercury (MeHg) was used as a proof-of-concept neurotoxicant to test the effectiveness of the NLR assay as a screening tool in toxicology. The locomotor effects of MeHg were evaluated in 6 dpf wild type eleutheroembryos exposed to waterborne MeHg (0, 0.01, 0.03 and 0.1μM). Afterwards, the NLR assay was tested in 48 hpf embryos subjected to the same MeHg exposure regimes. Embryos exposed to 0.01 and 0.03μM of MeHg exhibited significant increases in locomotion in both scenarios. These findings suggest that similar locomotor phenotypes observed in free swimming fish can be detected as early as 48 hpf, when locomotion is induced with nicotine.

MK-801 increases locomotor activity in a context-dependent manner in zebrafish

Zebrafish have become a popular animal model for behavioral neuroscience with an increasing number of studies examining the effects of pharmacological compounds targeting the brain. Exposure to MK-801, a non-competitive N-methyl-d-aspartate receptor antagonist has been shown to increase locomotor activity in zebrafish. However, others have failed to replicate this finding as several contradicting studies report no changes in locomotor activity following exposure to similar doses. In the current study we reconcile these behavioral reports by demonstrating that zebrafish do not exhibit changes in locomotor activity during exposure to non-sedative doses of MK-801. Interestingly, zebrafish do exhibit significant increases in locomotion if pre-treated with MK-801 followed by subsequent testing in a novel environment, which suggests the effects of MK-801 are context-dependent. In addition, we examine the potential role of the dopaminergic system in mediating MK-801’s locomotor stimulant effect by quantifying the levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the brains of zebrafish following a 30min exposure to 10μM of MK-801 (the dose found to induce the largest increase in locomotor activity). Our findings indicate that the MK-801-induced increase in locomotor activity is not accompanied by changes in whole-brain levels of dopamine or DOPAC. Overall, our results suggest that MK-801's context-dependent locomotor stimulant effect may be independent of whole-brain dopaminergic activation.

507. AAV-Mini-Agrin for Laminin-alpha2 Deficient CMD

Laminin alpha2 (merosin)-deficient congenital muscular dystrophy (CMD) (MDC1A) is characterized by severe muscle wasting, premature death in early childhood, and lack of effective treatment. The laminin alpha2 gene (around 10kb) is too large to fit into adeno-associated viral (AAV) vectors. Alternatively, a mini-agrin, which has similar function as the laminin alpha2, is utilized as the therapeutic gene. Our previous study with AAV1-mini-agrin gene therapy in dyw/dyw mice showed dramatic therapeutic effects in muscle pathology, but weak on peripheral neuropathy. The objective of the current study was to see whether the nerve pathology in MDC1A mice could be improved by mini-agrin using the AAV9 vector, which has superior ability to transduce nervous system.AAV9-mini-agrin (2 × 10^11vg/pup) was injected into 2 to 3 days old homozygous dyw/dyw pups via the temporal vein. The gene therapy treatment significantly improved mouse body weight (15 ± 45g in treated mice vs. 10.±.09g of untreated homozygous mice at 11 weeks of age, n=6, p< 0.001) and quadrupled life span (41.±0.04 wks of average life span in treated group vs. 10.18±.12 wks in untreated group, n= 9 to 24, p<0.0001, Fig a). In tests for motor function, untreated dyw/dyw mice were hypoactive in an open field and had overt deficits in a marble-burying assay. AAV9-mini-agrin gene therapy led to significant increases in locomotion (p=0.0373) and a marked rescue of marble-burying (Fig b. p=0.0068), an indication of both nerve and muscle functions. Gene therapy also resulted in a significant improvement in nerve pathology vs. the untreated controls shown by toluidine blue staining with more myelinated nerve fibers, and partial restoration of the basal lamina shown by electron microscopy in the treated mice. More importantly, the treated dyw/dyw male and female mice become fertile, which has never been seen before. Genotyping of the unborn pups confirmed that they were all homozygous dyw/dyw mice. This indicates that mini-agrin can partially replace the function of laminin alpha-2 in MDC1A and achieve therapeutic effects in muscle pathology, peripheral neuropathy, and fertility. This study represents a significant advancement in AAV-mediated gene therapy for MDC1A. View Large Image | Download PowerPoint SlideFig. Life span extension and functional improvement by the treatment. a. Both AAV9-CMV-mini-agrin and AAV9-CB-mini-agrin treatment resulted in significant improvement in mouse survival. n = 9 to 24, p < 0.0001. b. Treatment led to an overt increase in marble-burying. n=5, * p< 0.01.

010 — (BOR0176) PER2, PER3, and clock polymorphisms are not associated with juvenile myoclonic epilepsy in a sample of the Brazilian population

Sao Paulo (UNIFESP), number 0164/12. Results: The two-way ANOVA with repeated measures revealed significant effects of time [F (2,36) = 33.99, p b 0.001], prenatal treatment [F (1,36) = 4, 32 p b 0.05], and postnatal treatment [F (1,36) = 113.87, p b 0.001] and interaction prenatal treatment × postnatal treatment [F (1,36) = 5, 80, p b 0.05], time × postnatal treatment [F (2,36) = 33.54, p b 0.001], and prenatal treatment × postnatal treatment × time [F (2,36) = 3.28, p b 0.05]. Duncan's test revealed that the behavioral sensitization to AMP occurred in the 3rd day injection of SAL or AMP (5th day of treatment), with a significant increase in locomotion in the AMP-treated groups (3rd day N 1st day). Importantly, the prenatal treatment with POLY:IC potentiated behavioral sensitization to AMP. Discussion/conclusions: Our results indicate that prenatal POLY:IC administration potentiated AMP-induced behavioral sensitization and support the observation that patients with schizophrenia present an increase in the prevalence of substance use disorders.

Increased calcium/calmodulin-dependent protein kinase II activity by morphine-sensitization in rat hippocampus

Repeated exposure to drugs of abuse, such as morphine, elicits a progressive enhancement of drug-induced behavioral responses, a phenomenon termed behavioral sensitization. These changes in behavior may reflect long-lasting changes in some of the important molecules involved in memory processing such as calcium/calmodulin-dependent protein kinase II (CaMKII). In the present study, we investigated the effect of morphine sensitization on mRNA expression of α and β isoforms and activity of CaMKII in the hippocampus of male rats. Animals were treated for 3 days with saline or morphine (20mg/kg) and following a washout period of 5 days, a challenge dose of morphine (5mg/kg) were administered. The results indicate that morphine administration in pre-treated animals produces behavioral sensitization, as determined by significant increase in locomotion and oral stereotypy behavior. In addition, repeated morphine treatment increased mRNA expression of both α and β isoforms of CaMKII in the hippocampus. The present study also showed that induction of morphine sensitization significantly increased both Ca2+/calmodulin-independent and Ca2+/calmodulin-dependent activities of CaMK II in the rat hippocampus. However, acute administration of morphine (5mg/kg) did not alter either α and β CaMKII mRNA expression or CaMKII activity in the hippocampus. The stimulation effects of morphine sensitization on mRNA expression and activity of CaMKII were completely abolished by administration of naloxone, 30min prior to s.c. injections of morphine (20mg/kg/day×3 days). Our data demonstrated that induction of morphine sensitization could effectively modulate the activity and the mRNA expression of CaMKII in the hippocampus and this effect of morphine was exerted by the activation of opioid receptors.

The effect of sertindole on behavioural sensitisation to methamphetamine in mice

Similarly to various other addictive substances, methamphetamine (Met) produces, following repeated application, a strong increase in behavioural responses (particularly locomotor behaviour), a phenomenon termed behavioural sensitisation. In our previous studies we tested the effects of various psychotropic drugs on behavioural sensitisation to Met, particularly the effects of cannabinoid receptor ligands with different intrinsic activities and felbamate and memantine, antagonists of N-methyl-d-aspartate (NMDA) receptors. In the present study we investigated the influence of the antipsychotic drug sertindole (Srt) on sensitisation to the effects of Met on mouse locomotor behaviour in the Open field test. Male mice were randomly divided into 4 groups and were administered drugs seven times (from the 7&lt;sup&gt;th&lt;/sup&gt; to 13&lt;sup&gt;th&lt;/sup&gt; day of the experiment) as follows: (a) n&lt;sub&gt;1, 2&lt;/sub&gt;: Met at the doses of 2.5 mg/kg/day; (b)&amp;nbsp;n&lt;sub&gt;3&lt;/sub&gt;: Met&amp;nbsp;+ Srt at the doses of 2.5 mg/kg/day + 10.0 mg/kg/day; (c) n&lt;sub&gt;4&lt;/sub&gt;: Srt at the dose of 10.0 mg/kg/day. Locomotion in the Open field test was measured (a) after administration of vehicle on the 1&lt;sup&gt;st&lt;/sup&gt; day, (b) after the 1&lt;sup&gt;st&lt;/sup&gt; dose of drugs given on the 7&lt;sup&gt;th&lt;/sup&gt;&amp;nbsp;day, and (c) on the 14&lt;sup&gt;th&lt;/sup&gt; day after the &amp;ldquo;challenge doses&amp;rdquo; administered in the following way: n&lt;sub&gt;1&lt;/sub&gt;: Met; n&lt;sub&gt;2&lt;/sub&gt;: Met+Srt, n&lt;sub&gt;3&lt;/sub&gt;: Met; n&lt;sub&gt;4&lt;/sub&gt;: Srt. We found the following significant behavioural changes: (1) a stimulatory influence of Met and development of sensitisation after repeated treatment (n&lt;sub&gt;1&lt;/sub&gt;); (2) an inhibition of Met sensitisation in the case of a combined challenge dose of Met + Srt (n&lt;sub&gt;2&lt;/sub&gt;); (3) a stimulatory effect of Met when animals were repeatedly pre-treated with Met + Srt (n&lt;sub&gt;3&lt;/sub&gt;); (4) a significant inhibition of locomotion after the 1&lt;sup&gt;st&lt;/sup&gt; dose of Srt, that persisted even after the last Srt dose (n&lt;sub&gt;4&lt;/sub&gt;). Data concerning the involvement of sertindole in reward processes associated with drug addiction are not completely consistent and our results reflect this ambiguity to a certain extent. A combined challenge dose of Met + Srt administered after repeated pre-treatment with Met inhibited the development of behavioural sensitisation; on the other hand a Met challenge dose alone administered after repeated pre-treatment with Met + Srt produced a significant increase in locomotion.

Behavioral and neurochemical characterization of mice deficient in the N-type Ca2+ channel α1B subunit

N-type voltage-dependent calcium channels (VDCCs) play an important role in neurotransmission, synaptic plasticity, and brain development. They are composed of several subunits named α1, α2, δ, β and γ. The α1 subunit is essential for channel functions and determines fundamental channel properties. Since N-type VDCC are critically involved in the release of neurotransmitters and clinical relevance, we predicted that α1 subunit KO mice would show several alterations in behavior. In the present study, we investigated neuronal functions in mice lacking the α1B (CaV2.2) subunit of the N-type calcium channels. CaV2.2−/− mice exhibited a significant increase in locomotion on an activity wheel during the dark phase. Furthermore, when challenged with apomorphine, mutant mice showed enhanced locomotor activity. Cognitive functions were examined using a Y-maze task for short-term memory and a passive avoidance task for long-term memory. The Y-maze revealed no differences in spontaneous alternation behavior between mutant and wild-type mice. The passive avoidance test revealed that the latency time in mutant mice was significantly decreased. The mutant mice showed prepulse inhibition deficits reminiscent of the sensorimotor gating deficits observed in a large majority of schizophrenic patients. Decreases in baseline levels of dopamine and serotonin within the striata and frontal cortices of mutant mice were also observed. These results suggest that Ca2+ in the central nervous system modulates various neurophysiological functions, such as locomotor activity, long-term memory, and sensorimotor gating through the α1B subunit of the N-type calcium channels.

Effects of Byrsocarpus coccineus (Connaraceae) extract on the central nervous system (CNS)

In establishing the pharmacological profile of Byrsocarpus coccineus, we investigated the CNS effects of the aqueous leaf extract using the Y-maze, hexobarbitone sleeping time and hole board models in mice. In the Y-maze test, Byrsocarpus coccineus, BC (50–100mg/kg, p.o.) produced significant (P<0.05) increases in the time spent in the open arm at post-treatment times of 30–90min. Peak effect was elicited at 100mg/kg 30min post-treatment, with mice spending 2.63±0.21min in the open arm vs. 0.62±0.21min for control. This effect was significantly higher than that of diazepam, 1mg/kg p.o. (2.00±0.20min). At doses of 200 and 400mg/kg, the effect of BC in increasing the time spent in the open arm diminished with the effect at the higher dose (1.24±0.29min) being not significantly different from the control. In the hexobarbitone sleeping time test, BC (50–100mg/kg) increased the onset and decreased the duration of sleep, with effects only being significant at 100mg/kg (onset=7.00±1.18min and duration=10.00±1.84min vs. onset=3.43±0.81min and duration=20.71±2.34min for control). At doses of 200 and 400mg/kg, BC decreased onset and significantly increased sleeping time with the effect at the higher dose (onset=3.29±0.61min and duration=39.86±3.78min) being significantly lower than that of diazepam, 3mg/kg p.o., in respect of duration of sleep only (onset=3.14±0.26min and duration=87.29±9.87min). In the modified hole board experiment, BC (50–100mg/kg) caused an increase in both exploratory activity and locomotion, while at 200 and 400mg/kg the reverse was the case. These effects were not significant. Diazepam, 1mg/kg p.o., caused a non-significant increase in exploratory activity and a significant increase in locomotion (25.71±4.44 sectional crossings in 5min vs. 10.86±2.30 sectional crossings in 5min for control). Results obtained suggest that the aqueous leaf extract of Byrsocarpus coccineus possess a dose determined anxiolytic – sedative activity with no effect on exploratory activity and locomotion.

Intra-nigral MPTP lesion in rats: Behavioral and autoradiography studies

The present study investigated the motor response and possible changes in binding to D 1 and D 2 receptors after intra-nigral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) infusion on rats. The results indicated that MPTP-lesioned rats exhibited a significant reduction in locomotion and rearing frequencies observed in an open field 24 h after surgery. However, at 7 and 14 days after surgery the MPTP-lesioned rats showed a significant increase in locomotion in comparison to the control groups, as well as a decrease in immobility time. In addition, 21 days after surgery the behavioral measurements were unaltered by these procedures. Moreover, latency in initiating movement and catalepsy were unchanged by this neurotoxin on the same days of observation. An autoradiography approach indicated that there was a reduction in [ 3H]SCH 23390 binding in substantia nigra pars compacta (SNpc), substantia nigra pars reticulata (SNpr) and ventrolateral striatum in MPTP-treated rats 21 days after the surgery. [ 3H]raclopride binding remained unaltered by the MPTP treatment. These results suggest that compensatory plastic changes occur in D 1 dopamine receptors after partial lesion of nigral dopaminergic neurons. These alterations might be related to the occurrence and recovery of motor impairment observed in MPTP-lesioned rats.

Effects of acute bupropion administration on locomotor activity in adolescent and adult mice

Responses to some psychoactive substances seem to differ between adolescents and adults. Bupropion, an antidepressant which is also used for smoking cessation, induces a dose-dependent increase in locomotor activity in adult mice, although its behavioral actions in adolescents have not been evaluated. In the present study the effects of acute bupropion administration (5, 10, 15 and 20 mg/kg) on locomotor activity were examined in early adolescent (postnatal day (pnd): 29-31 days), late adolescent (pnd: 47-49 days) and adult (pnd > 70 days) male NMRI mice, using an infrared photocell system. Locomotion was recorded for a total period of 90 min. Results indicated that there were significant differences in motor activity counts between the three ages evaluated, with late adolescents being more active than early adolescents. Bupropion (at doses 20, 15 and 10 mg/kg) induced a significant increase in locomotion, but there was no significant interaction between age and treatment. This suggests that the locomotor-stimulating effects of bupropion can be observed at different ages (early adolescence, late adolescence and adulthood), although the detailed analysis of the temporal course of locomotion changes induced by different bupropion doses reflected some differences between ages. The lowest dose (5 mg/kg) failed to induce hyperactivity in either adolescent or adult mice.

Anxiolytic-like action in mice treated with nitrous oxide and oral triazolam or diazepam

Few animal studies have explored the interaction of nitrous oxide (N 2O) with a benzodiazepine (BNZ) administered by the oral route, as used in clinical procedures involving “conscious sedation”. The purpose of this study was to evaluate the relative “anxiolytic-like” and sedative effectiveness of N 2O, oral triazolam (TRIAZ; Halcion®) or oral diazepam (DIAZ; Valium®), either alone or in various combinations of drugs and doses. One hundred and twelve Swiss Webster male mice, 35–45 days old, were assigned to 28 groups, each of which contained four mice. The mouse staircase test was used for the assessment of anxiety (number of rearings) and sedation (number of steps ascended). Three doses of oral TRIAZ (0.1, 0.3, 1.0 mg/kg) or DIAZ (2.0, 3.5, 5.0 mg/kg) were given in combination with room air, or N 2O/O 2 at a N 2O concentration of 25, 50 or 75%. Each mouse was tested once. N 2O alone did not reduce NR in any concentration, but caused a significant increase in locomotion. DIAZ without N 2O reduced NR only with the middle and high doses, but the addition of N 2O significantly enhanced the anxiolytic-like effect of all DIAZ doses. TRIAZ, alone, reduced NR only in the highest dose, but added N 2O resulted in anxiolytic-like behavior with all three TRIAZ doses. The sedative effects of the BNZs were extremely variable. Only the middle dose of DIAZ plus 25% N 2O unequivocally reduced the number of steps ascended, i.e., caused sedation. TRIAZ lacked the inverted U-shaped dose-response relationship with NR usually seen with DIAZ. TRIAZ, therefore, provides better dose control. This behavioral animal model indicates that the optimal combinations for reduction of anxiety-like behavior with minimal effects on sedation are 0.1 mg/kg oral TRIAZ with 25% N 2O or 2.0 mg/kg oral DIAZ with 25% N 2O.

Excitotoxic neurodegeneration induced by intranasal administration of kainic acid in C57BL/6 mice

Glutamate excitotoxicity plays a key role in inducing neuronal cell death in many neurological diseases. In mice, administration of kainic acid, an analogue of the excitotoxin glutamate, results in hippocampal cell death and seizures. Kainic-acid-induced seizures in mice provide a well-characterized model for studies of human neurodegenerative diseases. However, C57BL/6 mice, which are often used for genetic analyses and transgenic and knockout studies, are resistant to excitotoxicity induced by subcutaneous administration of kainic acid. In the present study, kainic acid administered by the intranasal route was shown to result in continuous tonic-clonic seizures in C57BL/6 mice. These seizures continued for 1–5 h and successfully induced selective lesions in area CA3 of the hippocampus. The survival rate was high even after mice experienced severe seizures. The hippocampal lesions were associated with a high level of cyclooxygenase-2 production as well as astrogliosis. Administration of kainic acid also altered behavioral responses, with mice showing a significant increase in locomotion and rearing activity as indicated by an open-field test. This animal model could provide a valuable tool for exploring the role of excitotoxicity in neuropathological conditions and should be further evaluated in gene-targeting studies of neurodegenerative diseases.