The action of chlorpromazine on exploration in pairs of rats

Ontogenetic manganese exposure with perinatal 6-OHDA lesioning alters behavioral responses of rats to dopamine D₁ and D2 agonist treatments

The effect of neonatal manganese (Mn) exposure in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease was investigated. Pregnant Wistar rats were given drinking water with 10,000 ppm of Manganese (MnCl₂.4H₂O) from the time of conception until weaning on the 21st day after delivery. Control rats consumed tap water. Three days after the birth, other groups of neonatal rat pups were pretreated with desipramine (20 mg/kg ip 1h) prior to bilateral ICV administration of 6-OHDA or its vehicle, saline-ascorbic (0.1%) (control). Two months after the birth, striatal dopamine and homovanilic acid efflux measured by an in vivo microdialysis method were reduced in rats lesioned with 6-OHDA. Co-exposure to perinatal Mn did not modify neurotransmission alterations. However, there were prominent abnormalities in behavioral testing in rats perinatally exposed to Mn and treated neonatally with 6-OHDA. These findings demonstrate that although Mn did not further damage neurotransmitter activity in the neostriatum, ontogenetic exposure to Mn enhances the behavioral toxicity to 6-OHDA.

Neonatal co-lesion by DSP-4 and 5,7-DHT produces adulthood behavioral sensitization to dopamine D(2) receptor agonists

To assess the possible modulatory effects of noradrenergic and serotoninergic neurons on dopaminergic neuronal activity, the noradrenergic and serotoninergic neurotoxins DSP-4 N-(2-chlorethyl)-N-ethyl-2-bromobenzylamine (50.0 mg/kg, sc) and 5,7-dihydroxytryptamine (5,7-DHT) (37.5 microg icv, half in each lateral ventricle), respectively, were administered toWistar rats on the first and third days of postnatal ontogeny, and dopamine (DA) agonist-induced behaviors were assessed in adulthood. At eight weeks, using an HPLC/ED technique, DSP-4 treatment was associated with a reduction in NE content of the corpus striatum (> 60%), hippocampus (95%), and frontal cortex (> 85%), while 5,7-DHT was associated with an 80-90% serotonin reduction in the same brain regions. DA content was unaltered in the striatum and the cortex. In the group lesioned with both DSP-4 and 5,7-DHT, quinpirole-induced (DA D(2) agonist) yawning, 7-hydroxy-DPAT-induced (DA D(3) agonist) yawning, and apomorphine-induced (non-selective DA agonist) stereotypies were enhanced. However, SKF 38393-induced (DA D(1) agonist) oral activity was reduced in the DSP-4 + 5,7-DHT group. These findings demonstrate that DA D(2)- and D(3)-agonist-induced behaviors are enhanced while DA D(1)-agonist-induced behaviors are suppressed in adult rats in which brain noradrenergic and serotoninergic innervation of the brain has largely been destroyed. This study indicates that noradrenergic and serotoninergic neurons have a great impact on the development of DA receptor reactivity (sensitivity).

The effects of angelica essential oil in social interaction and hole-board tests

In our previous studies, we have demonstrated the anxiolytic effects of angelica essential oil in three anxiety models using mice. This study aimed to characterize the similar behavior effects of angelica essential oil in the social interaction test of anxiety and the hole-board test of exploration and locomotor activity in rats. These results indicate that angelica essential oil possessed a wide range of anxiolytic properties. In the social interaction test, angelica essential oil decreased aggressive behaviors at the doses of 21 and 42 mg/kg, while the doses of 21 and 42 mg/kg significantly increased social interaction time of the high light, unfamiliar test condition and 21 mg/kg could also prolong social interaction time of the high light, familiar test condition. In the hole-board test, angelica essential oil at 10.5 mg/kg significantly increased head-dipping counts and duration. Thus, our findings suggest the potential usefulness of angelica essential oil against various types of anxiety-related disorders and social failure.

Anxiolytic-like profile in Wistar, but not Sprague-Dawley rats in the social interaction test

RATIONALE

The social interaction test is a valuable behavioural model for testing anxiolytic drugs in rodents, quantifying the level of social behaviour between pairs of rats.

OBJECTIVE

The aim of the present study was to assess the appropriateness of the social interaction test for use with a Sprague-Dawley rat line, because of increasing use of this strain in targeted mutagenesis research.

METHODS

Sprague-Dawley and Wistar rats received either diazepam or mCPP or were exposed to different environmental conditions (lighting, social isolation prior testing, habituation, testing-time). General anxiety-related parameters measured were: duration of active social contact, frequency of active social contact, latency to first contact. Different forms of active social contact were recorded: number of crawls, follows and sniffs. Secondly, aversion-induced hippocampal serotonin release and serotonin content in brain regions were measured.

RESULTS

In Wistar rats habituation to the test substantially increased the time of social contact, an effect comparable with treatment with diazepam (1 mg/kg), whereas changes in the lighting level had less impact. Latency to the first contact increased under "anxiety-reducing" conditions, the frequency of contacts did not change consistently. Sprague-Dawley rats behaviour did not change under varying environmental conditions, and treatment with diazepam had only sedating effects at higher doses (5 mg/kg). Anxiogenic doses of mCPP caused reduced social interaction in both strains. Serotonin release and serotonin content were higher in the anxious Wistar rats.

CONCLUSIONS

Different rat strains as well as differing test conditions have a major impact on the outcome of this animal test for anxiety.

Different treatment regimens and the development of tolerance to nicotine's anxiogenic effects

The effects of different treatment regimens were investigated on the development of tolerance to the anxiogenic effect of nicotine (0.45 mg/kg) in the social interaction test of anxiety. Rats received nicotine (0.45 mg/kg/day) by intravenous injections (5 days/week), subcutaneous injections (5 or 7 days/week) or continuous infusion by osmotic minipump. In all groups, 4 days of nicotine treatment resulted in significant decreases in social interaction compared with the vehicle control groups, without changes in locomotor activity, indicating a specific anxiogenic effect. These significant anxiogenic effects persisted even after 4 weeks of treatment although they were less marked, indicating development of partial tolerance. No significant changes in the time spent in social interaction were found when rats were tested undrugged 24 and 72 h after the termination of nicotine treatment. There was no evidence that the treatment regimen affected the rate of development of tolerance, despite very different peak plasma nicotine concentrations.

Acute effects of chlorpromazine in a monkey operant behavioral test battery

The effects of acute chlorpromazine treatment were assessed using a complex operant test battery (OTB) containing five tasks thought to depend upon processes associated with short-term memory and attention [delayed-matching-to-sample (DMTS)], color and position discrimination [conditioned position responding (CPR)], motivation [progressive ratio (PR)], time perception [temporal response differentiation (TRD)], and learning [incremental repeated acquisition (IRA)]. Adult male rhesus monkeys were tested 15 min after IV injection of saline or chlorpromazine (0.010, 0.030, 0.100, or 0.175 mg/kg). Behavioral endpoints measured included percent task completed, response rate or latency, and response accuracy. The order of task sensitivity to disruption by chlorpromazine was TRD = PR = IRA = DMTS = CPR in which sensitivity was defined as a significant alteration in any aspect of task performance. Chlorpromazine slowed response rates in all tasks except TRD but did decrease accuracy in that task. These effects were similar to those noted in previous studies of acute chlorpromazine treatment. Specific motoric effects suggested decreased task initiation at doses that left general motor ability intact. This finding is similar to that noted in parkinsonism caused by chronic chlorpromazine treatment.

Effects of the beta-carboline, FG 7142, in the social interaction test of anxiety and the holeboard: correlations between behaviour and plasma concentrations

The behavioural effects of the beta-carboline FG 7142 were investigated in the social interaction test of anxiety and the holeboard test of exploration and locomotor activity. FG 7142 (5-20 mg/kg) produced a significant decrease in the time spent in social interaction by pairs of rats, without an accompanying decrease in motor activity. This anxiogenic effect was highly correlated with the plasma concentrations of FG 7142 for the rats receiving 5 and 10 mg/kg doses, but not for those receiving the 20 mg/kg dose. In the holeboard, FG 7142 had no effect on exploratory head-dipping at the doses tested, but selectively reduced locomotor activity and the number of rears. The profile of FG 7142 in these tests is compared with those of the beta-carbolines, B-CCE and B-CCP.

What can be learned from the effects of benzodiazepines on exploratory behavior?

The purpose of this review is to assess the value of using tests of exploratory behavior to study the actions of benzodiazepines. The methods of measuring exploration and the factors influencing it are briefly described. The effects of benzodiazepines on exploratory behavior of rats and mice are reviewed; and the dangers of interpreting the results of such tests in terms of any of the clinical effects of the benzodiazepines is stressed. Finally, the interactions between benzodiazepines and other drugs acting at the GABA-benzodiazepine receptor complex are described. The results of these experiments caution against global classification of compounds as benzodiazepine "antagonists."

Characteristics of an atypical benzodiazepine, Ro 5-4864

Ro 5-4864 is a 1,4 benzodiazepine which, atypically, does not bind to the classical CNS benzodiazepine receptors, but has high affinity for the peripheral type of binding site found both in the periphery and in the brain. Biochemical evidence for alternative sites of action for this compound is discussed. We review the behavioral profile of Ro 5-4864 (sedative, convulsant and anxiogenic in rodents) and also describe the behavioral effects of combining Ro 5-4864 treatment with benzodiazepines (e.g., diazepam, chlordiazepoxide) and with other drugs that modify the activity of benzodiazepines (Ro 15-1788, CGS 8216, picrotoxin, PK 11195, phenytoin). In the light of these interactions and electrophysiological evidence we conclude that the actions of Ro 5-4864 are most likely to be mediated at the GABA-benzodiazepine receptor complex in the CNS.

Behavioural actions of Ro 5-4864: a peripheral-type benzodiazepine?

Ro 5-4864 is a 1,4 benzodiazepine lacking typical benzodiazepine behavioural actions, and which has very low affinity for the "classical" CNS benzodiazepine binding sites. However, Ro 5-4864 has very high affinity for the peripheral type of binding site in the periphery and in the brain. Evidence is reviewed that Ro 5-4864 is sedative, convulsant and anxiogenic in rodents. We also describe the effects of combining Ro 5-4864 treatment with benzodiazepines (e.g. diazepam, chlordiazepoxide) and with other drugs that modify the activity of benzodiazepines (Ro 15-1788, CGS 8216, picrotoxin, PK 11195, phenytoin). The binding sites that might be mediating these behavioural actions of Ro 5-4864 are discussed.

Amphetamine psychosis and schizophrenia: a dual model

Several of the behavioral consequences of acute and chronic amphetamine treatment were evaluated and related to the underlying neurochemical correlates of drug treatment. It was suggested that decreased noradrenergic activity after long-term amphetamine treatment influences stimulus sampling, whereas enhanced dopaminergic activity was responsible for the progressive augmentation of stereotypy and self-stimulation behavior observed after long-term exposure to amphetamine. It was hypothesized that amphetamine-induced psychosis and the symptomatology associated with schizophrenia are related to alterations in both norepinephrine and dopamine activity.

Exploratory behaviour and aversive thresholds following intra-amygdaloid application of opiates in rats

Rats were bilaterally implanted with guide cannulae aimed at the central or medial nucleus of the amygdala. Microinjections of morphine (10 microgram) at both sites significantly elevated the threshold of response in the flinch-jump test; but only at medial sites did naloxone (1 microgram) antagonise this effect. However, in the hole-board test, an opposite pattern of results emerged. Morphine injections into the central nucleus produced naloxone-reversible reductions in both exploration and activity whilst, in the medial nucleus, the morphine-induced decrease in exploration was not reversed by naloxone. It is concluded that (1) the presence or absence of naloxone-sensitive opiate receptors cannot always be deduced on the basis of a single behavioural test and (2) within the amygdaloid complex, two distinct naloxone-sensitive opiate systems appear to be involved in the modulation of behavioural responses to different forms of stimulation.

Mediation of central prostaglandin effects by serotoninergic neurons

Ten days after administration of 5,6-dihydroxytryptamine, which causes degeneration of central serotoninergic neurons, the depressive behavioral effects of PGF2 alpha and PGE2 were evidently inhibited. Central chemical serotoninectomy abolished the hyperthermic and hypertensive effects of PGF2 alpha, but only slightly affected those of PGE2. It is concluded that serotoninergic neurons mediate the depressive behavioral action of both PGF2 alpha and PGE2. They also mediate the hyperthermic and hypertensive action of PGF2 alpha but not of PGE2. This suggests that these prostaglandins have different central modes of action.

Influence of 6-hydroxydopamine on the behavioral effects induced by apomorphine or clonidine in rats

The aim of this paper is to examine if central chemical sympathectomy induced by two injections of 6-hydroxydopamine (6-OHDA) in a dose of 250 mug intracerebroventricularly (i.c.v.) affects behavioral phenomena elicited by apomorphine (AP) (1 or 1.2 mg/kg i.p.) or clonidine (CL) (0.1 MG/KG, 5 Or 1 mug/kg i.p.). Experiments were carried out on male Wistar rats. The time of duration of several components of behavior and the degree of irritability of rats were measured. Moreover, open field and hole test were performed. The lower dose of AP did not affected behavior of rats. The higher dose increased the locomotor and exploratory activity of animals. 6-OHDA potentiated these effects of AP. CL (0.1 mg/kg) had a depressive effect on the rats' behavior, which was potentiated by 6-OHDA. CL (5 mug/kg) had no effect on the rats' behavior, but in a dose of 1 mug/kg caused excitatory behavior. This type of behavior was abolished by 6-OHDA. In conclusion, central chemical sympathectomy caused increased sensitivity of the central nervous system on AP. Excitatory behavioral effects of CL in low dosage may be connected with stimulation of central adrenergic receptors. Depressive behavioral effect of CL in high dosage is unspecific. Central chemical sympathectomy affects by different methods the reactivity of dopaminergic and noradrenergic neurons.

The reliability of the hole-board apparatus

Two aspects of the reliability of the hole-board apparatus were investigated-the similarity between scores of different samples of the same population on their first exposure to the apparatus, and the test-retest reliability. Rats and mice were given a 5-min exposure to the hole-board and then retested for 5 min after 1, 2 or 8 days. Male rats and mice showed good initial exposure reliability, whereas the female mouse groups differed significantly. All animals showed a positive test-retest correlation (range 0.31-0.78), but a homogeneous group (e.g. all animals habituating) produced higher correlations (range 0.60-0.99). Comparison of scores on the two 5-min exposures showed that not all groups showed significant habituation, but the animals exposed to the hole-board for two 10-min periods showed both significant habituation and test-retest reliability.