Comparisons of the acute effects of cholinesterase inhibitors using a neurobehavioral screening battery in rats

The clinical signs of intoxication produced by cholinesterase inhibitors, many of which are used as pesticides, are considered important information for regulatory purposes. We conducted acute studies of cholinesterase inhibitors to compare their effects as determined by a functional observational battery (FOB) and motor activity. The acute effects of two carbamates (carbaryl, aldicarb) and five organophosphates (OP) (chlorpyrifos, diazinon, parathion, fenthion, and diisopropyl fluorophosphate, or DFP) were evaluated on the day of dosing at the time of peak effect, at 1 and 3 days, and 1 week after dosing (oral gavage, in corn oil). A high dose was selected that produced clear cholinergic signs, and lower doses were chosen to produce a range of effects. Generally all cholinesterase inhibitors produced autonomic signs of cholinergic overstimulation (salivation, lacrimation, and miosis), hypothermia, mild tremors and mouthsmacking (chewing motions), lowered motor activity, decreased tail-pinch response, and altered neuromuscular function (gait changes and increased foot splay). The measures generally found to be most sensitive on the day of dosing were body temperature, motor activity, gait, and the presence of mouth-smacking and fine tremors. However, no single measure was the most sensitive across all compounds; for example, the lowest dose of fenthion decreased motor activity by 86% but did not alter the tail-pinch response, whereas the lowest dose of parathion did not lower activity but did decrease the tail-pinch response. For some measures, differences in the slopes of the dose-response curves were evident. Many effects were still observed at 24 h, but recovery was apparent for all compounds. Interestingly, residual effects at 72 h were obtained with the carbamates (carbaryl, aldicarb) as well as with the OP fenthion, but not with the other compounds. Thus, the overall clinical picture of toxicity was similar for these cholinesterase inhibitors, but compound-specific differences emerged in terms of the individual measures, dose-response, and time course.     

Striatal dopamine and motor activity changes observed shortly after lithium administration

Summary Lithium chloride was given to rats i.p. at single doses of 2 and 10 meq/kg, respectively. It produced a suppression of motor activity and an increase in the dopamine content of the striatum. The magnitude of these effects were dose- and time-dependent as well as transient in nature. After 60 min of injection, the higher dose (10 meq/kg) reduced motor activity by 67% and increased striatal dopamine content by 56% while the lower dose (2 meq/kg) reduced motor activity by 42% and elevated striatal dopamine by 36%. These effects vanished 24 h after administration regardless the dose employed.None of the two doses of LiCl altered either dopamine biosynthesis in vivo (measured as the accumulation of a precursor of synthesis after decarboxylase inhibition), or the activity of tyrosine hydroxylase ex vivo under subsaturating conditons (i.e. enzyme activity in the tissues obtained from the animals post mortem).An increased deamination of tyramine by mono-amineoxidase (MAO) was found in striatal homogenates after 60 min of the injection of 2 or 10 meq/kg of LiCl. This was due to a lowerK _m for the substrate as revealed by kinetic studies. LiCl treatment did not change the proportion of MAO AB.As neither dopamine synthesis was increased nor the activity of the catabolic enzyme MAO was reduced (but it was oppositely enhanced), the increment in striatal dopamine content might have likely resulted from a reduced release and/or an increased amine reuptake by the neurons. We postulate that the reduced motor activity observed shortly after injection of LiCl would be related to an interference with striatal dopaminergic neurotransmission.     

Tolerance and sensitization to inhaled 1,1,1-trichloroethane in mice: results from open-field behavior and a functional observational battery

Rationale 1,1,1-Trichloroethane (TCE), a representative abused solvent, has well described acute behavioral effects in animals. Much less is known about repeated high-concentration exposures as would be encountered in inhalant abusers. Tolerance has been demonstrated in some, but not all, studies with TCE while sensitization has also been seen with other abused solvents.Objective The present study was designed to further characterize changes in the effects of repeated exposure to TCE on a variety of mouse behaviors.Methods Mice were tested using locomotor activity as well as a functional observational battery (FOB) both before and after a regimen of daily exposures to various concentrations of TCE.Results The initial locomotor effects of acute 30-min exposures to TCE were biphasic with concentration-dependent increases in activity at lower concentrations and decreases observed at higher concentrations. The profile of acute effects as measured by the FOB included changes in posture, decreased arousal, disturbances in gait, delayed righting reflexes, and decreased sensorimotor reactivity. Animals were then divided into five groups and exposed 30 min/day to either air or one of four concentrations of TCE (2,000, 6,000, 10,000, or 13,300 ppm) for 15 consecutive days. The TCE concentration used primarily affected the magnitude of change, not whether tolerance or sensitization occurred. Tolerance developed on the measures of forelimb grip strength, inverted screen, and number of rears. Conversely, sensitization developed to measures of locomotor activity.Conclusion Depending on the behavioral measure, both tolerance and sensitization can occur in mice with repeated exposure to TCE. Both of these phenomena are characteristic of drugs of abuse.     

The tryptolines: Effect of intraventricular administration on spontaneous motor activity of rats

The pharmacologic properties of the tryptolines, hindered analogues of the tryptamines, were studied behaviorally in rats. Following intraventricular injections, it was found that spontaneous motor activity decreased markedly during the initial 25 mins when compared with saline. Since both the tryptolines and tryptamines have been shown to be inhibitors of 5-hydroxytryptamine uptake, it may be possible that these compounds are acting indirectly through an effect on the serotonergic system.     

Effects of NMDA receptor antagonists on cocaine-conditioned motor activity in rats

NMDA receptor antagonists have been reported to affect learned behaviors conditioned with abused drugs, with the outcome dependent, in part, on the class of NMDA receptor antagonist used. The present study tested the ability of various site-selective NMDA receptor antagonists to modify cocaine-conditioned motor activity. Two procedures were used for independently assessing drug effects on spontaneous activity and expression of cocaine-conditioned behavior. In the conditioning experiments, rats were administered i.p. injections of cocaine (30 mg/kg) or saline paired with distinctive environments. Spontaneous horizontal activity was dose-dependently enhanced by dizocilpine (0.03-0.3 mg/kg) and memantine (1-30 mg/kg), but not by D-CPPene (3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid; SDZ EAA 494; 1-10 mg/kg), ACEA-1021 (5-nitro-6,7-dichloro-1,4-dihydro-2, 3-quinoxalinedione; 3-56 mg/kg), or eliprodil (3-30 mg/kg). Higher doses of memantine, D-CPPene (1-10 mg/kg), eliprodil (3-30 mg/kg), or ACEA-1021 reduced vertical activity. Following five cocaine-environment pairings, rats displayed significant increases in motor activity when exposed to the cocaine-paired environment. The following antagonists were administered prior to the conditioning test: dizocilpine (MK-801; 0.03-0.1 mg/kg), memantine (1-10 mg/kg), D-CPPene (0.3-3 mg/kg), ACEA-1021 (3-10 mg/kg), and eliprodil (1-10 mg/kg). Of these, memantine, ACEA-1021 and, to the lesser degree, eliprodil attenuated expression of cocaine-conditioned motor activity at doses that did not significantly affect spontaneous motor activity. These results show that cocaine-conditioned behaviors can be selectively modulated by some, but not all, NMDA receptor antagonists.     

Effects of chronically administered nicotine and saline on motor activity in rats

This study investigated the differential effects of chronically administered nicotine and saline on motor activity in the rat. Nicotine was administered via a subcutaneously implanted osmotic minipump to effect an 8 hour off, 16 hour on, flow. Subjects were 48 male and 48 female albino rats, each about 165 days old. Activity was monitored every hour for 192 consecutive hours. Results indicated that the female animals were more active than the males, and that animals receiving nicotine were significantly more active on the first two days of drug administration than control animals; however, by the fourth day there were no significant differences between the activity levels of animals that received nicotine and those of control animals.     

Strain-dependency in motor activity and in concentration and turnover of catecholamines in synchronized rats

Circadian rhythm in motor activity was studied with an Animex motimeter in six strains of rats (ACI, BH, BS, DA, LEW, TNO) synchronized by a 12 hr light: 12 hr dark cycle. ANOVA revealed significant interstrain differences in motor activity as well as in the concentration and turnover of central noradrenaline and dopamine. Strain-dependent differences were also found with regard to tyrosine hydroxylase inhibition on motor activity. However, no significant interstrain correlations were found between endogenous concentration and/or turnover rates of the catecholamines and motor activity in normal and drug-treated rats.     

Effects of nicotine on two types of motor activity in rats

Effects of injections of two doses of nicotine (0.2 and 0.4 mg/kg body wt) were tested on general activity (in a photocell chamber) and on locomotor activity (in an activity wheel) in male and female rats of two ages (40 and 90 days). Behavior was monitored under light and dark conditions at 15, 30, and 45 min post-injection over a period of 12 days. A general excitatory effect of nicotine was observed in the photocell chamber, with the high dosage greatly increasing activity for younger and female animals. In the activity wheel an initial depressant effect was observed followed by excitation at the lower dose. No evidence for tolerance or difference between light and dark test conditions was found.     

Enhanced motor activity and brain dopamine turnover in mice during long-term nicotine administration in the drinking water

Nicotine was administered chronically to NMRI mice in their drinking water in gradually increasing concentrations to measure gross motor activity and brain nicotine concentrations over 24 h on the 50th day of nicotine administration. Also, the striatal postmortem tissue concentrations and accumbal extracellular concentrations of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured to study the role of dopaminergic systems in nicotine-induced hyperactivity in mice. The cerebral nicotine concentration was at its highest at the end of the dark period. The activity of nicotine-treated mice and their striatal DA metabolism were parallelly increased at 2 to 3 h after midnight and in the forenoon. Microdialysis experiments carried out in the forenoon showed that the extracellular levels of DA and DOPAC were elevated in the nucleus accumbens of these mice. Nicotine did not alter the circadian rhythmicity of activity in the mice. Rather, our findings suggest that the mice consume more nicotine when active and this might lead to enhanced release and metabolism of DA and further, to enhanced motor behavior. These findings support the suggestions that nicotine's effects on limbic and striatal DA are critical for its stimulating effects.     

Phencyclidine: Effects on motor activity and brain biogenic amines in the guinea pig

Previous reports suggesting that the behavioral response of the guinea pig to phencyclidine (PCP) administration is more similar to the effects of PCP observed in higher animals than those observed in mice and rats prompted us to investigate the effects of PCP on spontaneous motor activity and brain biogenic amine levels in the guinea pig. Doses of 2.5 and 5.0 mg/kg PCP were found to significantly elevate spontaneous motor activity; however, 7.5 mg/kg PCP produced highly variable results which were not significantly different from control. The concentrations of tryptophan, serotonin, 5-hydroxyindoleacetic acid, and norepinephrine were measured in the forebrain and hindbrain of previously drug naive animals 30min after administration of 5 mg/kg PCP. As compared to saline injected control animals, PCP was observed to have no effect on any of the neurochemical determinants measured. Contrary to previous reports, these data suggest that PCP produces behavioral effects in the guinea pig which are not unlike those observed in mice and rats. Furthermore, the effects which we report on spontaneous motor activity are not related to changes in the regional concentration of any of the neurochemical variables which were measured.     

Opiate receptors may mediate the suppressive but not the excitatory action of ACTH on motor activity in rats

Subcutaneous injections of adrenocorticotropin (ACTH) or of the opiate antagonist naltrexone produced a one (2.0 mg/kg) dpressed, whereas smaller doses of ACTH (50 micrograms/kg) and of naltrexone (0.125 and 0.25 mg/kg) stimulated motor activity in the open field test. Furthermore, naltrexone at a dose level that had no effect on motor activity blocked the suppressive effect of the high doses of ACTH but had no effect on the stimulating effect of the intermediate dose of ACTH. Finally, chronic naltrexone administration resulted in enhanced sensitivity to the suppressive but not to the stimulating effect of ACTH on motor activity. It is argued that opiate receptors may play a selective role in the effect of ACTH on motor activity. Such receptors may mediate the supressive effect of high doses of ACTH whereas other, naltrexone insensitive receptor systems may mediate the stimulating effect of ACTH on activity functions.     

Development of motor activity in young rats following perinatal methadone exposure.

Ambulatory behaviors of 21, 45, and 60 day old rats exposed to methadone (5 mg/kg) during gestation and/or lactation were studied by assessing locomotion in an activity cage, open field, and activity wheel, and latency times to step down from an elevated platform. Methadone-exposed rats were found to be generally less active than controls at 21 days of age and more active than saline-treated pups at the 45 and 60 day test periods. In addition, behavioral responses appeared to be dependent on the timing and duration of opioid treatment. These data suggest that prenatal and/or postnatal methadone exposure affects behavior in young rats and provide a functional correlate to our earlier observations of microscopic and neurochemical changes in the brains of methadone-treated offspring.     

Effects of a single dose of 3,4-methylenedioxymethamphetamine on circadian patterns, motor activity and sleep in drug-naive rats and rats previously exposed to MDMA

Rationale Despite the well documented neurochemical actions of 3,4-methylenedioxymethamphetamine (MDMA), acute effects in rats previously exposed to the drug have not been extensively explored.Objective To examine motor activity and vigilance effects of MDMA in drug-naive rats and in rats exposed to the drug 3 weeks earlier.Methods MDMA (15 mg/kg, IP) was administered to Dark Agouti rats. Motor activity, wakefulness, light slow wave sleep (SWS-1), deep slow wave sleep (SWS-2) and paradoxical sleep (PS), sleep and PS latencies were measured. Acrophases and amplitudes of the 24 h cycles were calculated by cosinor analysis. In parallel groups, local cerebral glucose utilization (lCMR_glu) and (³H)-paroxetine binding were measured in motor areas of the brain.Results In drug-naive rats MDMA caused marked increases in motor activity and wakefulness for at least 5–6 h. Circadian patterns of motor activity and sleep/vigilance parameters were altered up to 5 days after treatment. Despite most parameters tending to return to normal, there were still significant effects of MDMA on motor activity, wakefulness, and SWS-2 28 days later. Acute MDMA administration caused significant increases in lCMR_glu, but after 3 weeks lCMR_glu was decreased in the same brain areas. No significant change in [³H]paroxetine binding was observed in motor areas, although significant reductions were seen elsewhere (neocortex –81%). In rats exposed to MDMA 3 weeks earlier, most acute effects induced by MDMA administration were similar to those in drug-naive rats, but shorter duration of the acute effects were found in motor activity and vigilance.Conclusions Our findings provide evidence that MDMA use can lead to long-term changes in regulation of circadian rhythms, motor activity and sleep generation.     

Diurnal variations in the motor activity of the rat: Effects of inhibitors of the catecholamine synthesis

Summary The effects of the inhibitor of the tyrosine-hydroxylase H 44/68 and the inhibitor of the dopamine--hydroxylase FLA 63 on the diurnal variations of the motor activity was studied in male Wistar rats, which were kept under standardized conditions of light and darkness (L:D=12:12h). The motor activity was continuously registered in groups of 5 rats using a two-channel Animex motimeter. During light FLA 63 (40 mg/kg, s.c.) greatly increased motor activity on acute application and during darkness the physiological elevation in motor activity was further but slightly increased. H 44/68 (200 mg/kg, i.p.) also increased motor activity during light, but in contrast to FLA 63 greatly reduced motor activity during darkness. The results indicate that though dopamine and noradrenaline are involved in the regulation of behavioural components, one or the other catecholamine may play a predominant role at different times of the day. Thus, it seems worthwhile to study the effects of drugs separately during light and during darkness.Parts of this work were presented at the 16th Spring Meeting of the German Pharmacological Society, Mainz 1975 (Lemmer and Berger, 1975 a) and at the Vth Congr. Pol. Pharmacol. Soc., Szczecin 1975 (Berger and Lemmer, 1976)     

Discovery of novel PTP1B inhibitors with antihyperglycemic activity

Aim:

To discover and optimize a series of novel PTP1B inhibitors containing a thiazolidinone-substituted biphenyl scaffold and to further evaluate the inhibitory effects of these compounds in vitro and in vivo.

Methods:

A total of 36 thiazolidinone substituted biphenyl scaffold derivatives were prepared. An in vitro biological evaluation was done by Enzyme-based assay. The in vivo efficacy of 7Fb as an antihyperglycemic agent was evaluated in a BKS db/db diabetic mouse model with a dose of 50 mg·kg^-1·d^-1 for 4 weeks.

Results:

The in vitro biological evaluation showed that compounds 7Fb and 7Fc could increase the insulin-induced tyrosine phosphorylation of IRβ in CHO/hIR cells. In in vivo experiments, compound 7Fb significantly lowered the postprandial blood glucose, from 29.4±1.2 mmol/L with the vehicle to 24.7±0.6 mmol/L (P<0.01), and the fasting blood glucose from 27.3±1.5 mmol/L with the vehicle to 23.6±1.2 mmol/L (P<0.05).

Conclusion:

A novel series of compounds were discovered to be PTP1B inhibitors. Among them, compound 7Fb significantly lowered the postprandial and fasting glucose levels, and the blood glucose level declined more rapidly than in metformin-treated mice. Thus, 7Fb may be a potential lead compound for developing new agents for the treatment of type II diabetes.     

凋亡抑制蛋白抑制剂的设计、合成及体外活性初步评价

目的 设计并合成凋亡抑制蛋白（IAPs）小分子抑制剂。方法 基于对Smac和Caspase-9分别与XIAP-BIR3结合位点的分析,辅以分子对接实验,设计并合成两类结构的化合物;采用荧光极化各向异性（FPA）竞争试验法测定合成的目标化合物对XIAP和cIAP1的抑制活性。结果 合成两类结构共16个新肽类化合物,其结构经MS和¹H-NMR谱确证;荧光极化各向异性（FPA）竞争试验结果显示,噻唑烷环衍生物Ⅱ对XIAP-BIR3和cIAP1-BIR3具有显著的抑制活性,其中,化合物Ⅱf抑制XIAP-BIR3和cIAP-BIR3的IC₅₀值分别为0.29、0.055 μmol·L^-1。结论 发现了新的IAPs抑制剂,并得出初步构效关系,为进一步的结构优化奠定了基础。     

The effect of amantadine on motor activity and catalepsy in rats

The effect of amantadine on motor activity was investigated in rats. The compound was used at doses which antagonized the catalepsy induced by spiroperidol, triperidol, chlorpromazine and reserpine. These doses moderately stimulated motor activity in normal rats; their activity was effectively antagonized by spiroperidol, chlorpromazine, phenoxybenzamine but only slightly, if at all, by -methyltyrosine, dimethyldithiocarbamate and reserpine. The behavioral effects of amantadine in normal and reserpinized rats were potentiated by l-DOPA, nialamide, desipramine and, in particular, by cocaine. The cocaine-induced potentiation of the amantadine effect was prevented by spiroperidol. -Methyltyrosine did not influence the antagonism of amantadine towards spiroperidol-induced catalepsy. Noradrenaline and dopamine levels in the whole brain and dopamine levels in the corpus striatum were unaltered by amantadine. The main mechanism of action of amantadine appears to be the activation of central dopamine receptors.     

An assessment of the spontaneous activity of rats administered morphine,phencyclidine, or nicotine using automated and observational methods

The effects of morphine, phencyclidine, and nicotine on motor activity in rats were characterized using both observational and automated methods. Activity was scored observationally using a time-sampling method that tabulates discrete response categories (still, locomotion, rearing, sniffing, licking, gnawing, head down, swaying, grooming, falling). Behavior was assessed automatically using an activity monitor that records both the time and activity counts spent in large and small (less than 3 cm) movements, rearing, and resting. The following results using male Sprague-Dawley rats represent significant differences from saline-treated controls. Morphine (1–4 mg/kg SC) increased the incidence of locomotion, sniffing, swaying, and grooming depending on the time after drug injection. These changes corresponded to an increase in large and small movement counts and time as measured by the activity monitor. Phencyclidine (1.25–5 mg/kg SC) caused dose-related increases in the incidence of locomotion, sniffing, swaying, and falling, and induced greater large and small activity movement counts and time especially after the 5 mg/kg dose. Nicotine (0.033–0.33 mg/kg SC) decreased the incidence of rearing and increased the frequency of sniffing and grooming. These changes corresponded to a decrease of rearing activity and to a slight increase in small activity. The present data indicate that morphine, phencyclidine, and nicotine exert dose-related and time-related appearances of various categories of behavior in the rat, and that the data from the automated method complement the findings of the direct observational method.     

The effects of cimetidine on schedule-controlled responding and locomotor activity in rats

The effect of intraperitoneal injections of cimetidine, a selective histaminergic H₂-receptor blocking agent, on operant behavior and locomotor activity were examined in rats. Cimetidine (1–100 mg/kg) failed to show any significant effect on responding maintained under a fixed-ratio (FR) 30 fixed-interval (FI) 5-min schedule of food presentation. A higher dose of cimetidine (300 mg/kg) produced decreases in both FR and FI rates of responding. In contrast, 100 mg/kg of cimetidineincreased the response rate and decreased reinforcement rate in rats performing under a schedule requiring the temporal spacing of responses (DRL-10 sec). Cimetidine (10–300 mg/kg) did not induce significant changes in locomotor activity in the rat. These data suggest that cimetidine is more potent in altering the steady low rate of responding under a DRL schedule of food presentation, than responding maintained under a multiple FR FI schedule, and that cimitidine is even less potent in altering locomotor activity.     

Separate and combined effects of caffeine and alprazolam on motor activity and benzodiazepine receptor binding in vivo

CD-1 mice received single intraperitoneal (IP) doses of caffeine-sodium benzoate (caffeine doses: 0, 20 and 40 mg/kg) followed by injections of alprazolam-propylene glycol (0, 0.05, and 2 mg/kg, IP) to determine brain concentrations, effects on in vivo receptor binding of a specific high-affinity benzodiazepine receptor ligand [³H]Ro15-1788, and effects on motor activity over a 1-h period. A behavioral monitoring device, using infrared sensors, measured horizontal and ambulatory activity. Caffeine produced significant increases in all motor activity measures as compared to vehicle treatment, with low dose caffeine (with brain concentrations of 13 µg/g) stimulating activity to a greater degree than the high dose (with brain concentrations of 30 µg/g). The overall effect of caffeine on benzodiazepine receptor binding was not significant. Alprazolam significantly diminished motor activity and altered benzodiazepine receptor binding. Low dose alprazolam increased binding, while the high dose diminished it. Caffeine and alprazolam antagonized each other's behavioral effects in this study, but did not alter each other's uptake into brain. Alprazolam's antagonism of caffeine-induced motor stimulation was associated with decreases in receptor binding, whereas caffeine's reversal of alprazolam-induced motor depression was not associated with any changes in binding. The lack of a clear association between drug effects on benzodiazepine binding and on motor activity suggests that behavioral effects of caffeine and alprazolam may be mediated by other sites in addition to the benzodiazepine receptor.Supported in part by Grants MH-34223, AG-00106, and DA-05258 from the Department of Health and Human Services