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PubMed2002

Characteristics of girls with early onset disruptive and antisocial behaviour.

BACKGROUND: Crime, particularly among juvenile females, has increased in recent years. Little is known, however, about the development and precursors in childhood of female delinquent behaviour. This is primarily due to a lack of consensus on how to define and assess female antisocial behaviour, and a lack of studies using sufficiently large samples. METHOD: A community sample of 2451 girls between the ages of five and eight years were recruited into a longitudinal study following the enumeration of 103,238 households in the city of Pittsburgh. Data on disruptive and antisocial behaviours were collected from parents, teachers and children during the first wave of the study. RESULTS: Prevalence rates of disruptive disorders varied by choice of informants and measurement thresholds. The prevalence of most disruptive behaviours was similar across the four age cohorts. Where there were differences, parents of younger girls tended to report fewer problematic behaviours compared with parents of older girls. Teachers reported more disruptive behaviours than parents and, by their reports, older girls were more likely to show oppositional/defiant behaviour and relational aggression than younger girls. Girls scoring highly on several domains relative to their peers were over-represented in disadvantaged neighbourhoods. CONCLUSIONS: A range of disruptive disorders are present among a subgroup of females at an early age, particularly among girls in the most disadvantaged neighbourhoods. Longitudinal follow-up is required to examine the developmental trajectories and predictive utility of these behaviours. The implications for clinical interventions are discussed.

Adolescent↗
PubMed2002

Does self-control account for the relationship between binge drinking and alcohol-related behaviours?

INTRODUCTION: Gottfredson and Hirschi's theory that there is an underlying factor accounting for all sorts of antisocial behaviour has attracted widespread theoretical and empirical attention. One of their most controversial statements is a 'generality' hypothesis, a notion that criminal, deviant and reckless acts are highly correlated because they are caused by individual differences in self-control. In this paper, we examine the extent to which self-control accounts for the relationship between two behaviours: binge drinking and involvement in alcohol-related behaviours, including criminal behaviour. METHOD: Questionnaires were given to students at a southern US university. A final sample of 241 students (35% males, 91% whites, aged 17-40). One question concerned binge-drinking, 11 others related to other alcohol-related behaviour; a 24-item scale measured self-control and sex was recorded. A probit model was used to test the effect of low self-control on binge drinking and on other alcohol-related behaviours. It was found that self-control exhibits a positive effect on both. But binge drinking and other alcohol-related behaviours are correlated, so a further analysis using a bivariate probit model was undertaken using a naïve model (no covariates), an unconstrained model (allowing self-control to exert a unique effect on both outcomes), and a constrained model forcing self-control to be the same for both outcomes. RESULTS: Our results suggest that while low self-control is a significant predictor of both binge drinking and alcohol-related problems, it does not fully account for the relationship between the two outcomes. In addition, separate estimation for each sex reveal a substantively different pattern of results. DISCUSSION: Further research is needed to disentangle the differences between the sexes. Situational factors, especially in males, may account for adverse alcohol-related behaviours. Other measures of self-control are also needed.

Adolescent↗
PubMed1998

Behavioural suppression of female pine voles after replacement of the breeding male

Examination of the mechanism of reproductive suppression includes determining which cues are involved and the context in which they occur. We studied groups of pine voles, Microtus pinetorum, that were disrupted by the replacement of the breeding male and compared them with intact family groups. If reproductive suppression is mediated by chemical cues, then soiled bedding should be sufficient to prevent production of litters by daughters. If reproductive suppression involves a behavioural component, we should observe aggressive behaviours or those indicative of dominance interactions directed from the mother towards the daughter or the replacement male. If replacement of the breeding male leads to conflict between the breeding female and her daughter, then more aggression or dominance interactions would be expected in disrupted than in intact families. The presence of the mother decreased reproduction by daughters, but chemical cues alone were not sufficient to prevent the daughter from mating with the replacement male. Rather, this decrease in reproduction seemed to be mediated by behavioural interactions. We propose that the mother's tugging on the daughter may lead to subordination of the daughter. The mother's presence may also alter the behaviour patterns of the male and daughter, which could delay reproductive activation of the daughter, prevent the formation of pair bonds or inhibit sexual behaviour. These behavioural interactions appear to depend on the presence of an unfamiliar male, because tugging, for example, was less frequent in intact family groups. Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Female behaviour, sexual competition and mate guarding in the blue crab, Callinectes sapidus

Blue crabs mate immediately after the female's final moult. We tested the influence of female moult stage, sex ratio and male size on the pre-mating behaviour of both sexes, and the ability of males to pair with females and aggressively compete for access to females. We observed crabs in field enclosures and surveyed pre-copulatory mate-guarding patterns in the field. Female behaviour changed as they progressed through the final moult cycle, such that early moult-stage females avoided males, but late moult-stage females initiated pair formation. The changes in female behaviour influenced both the behaviour and pairing capability of males. Males courted and paired with late moult-stage females on their first attempt, but pursued early moult-stage females because their first attempts to pair often failed. In the field, early moult-stage females were paired less often than late moult-stage females. The pre-mating behaviour of both sexes also varied with sex ratio; when males were abundant, males traded courtship for forced capture and females courted less. Large males were more successful at take-overs, but did not pair more often with late moult-stage females, suggesting that large males do not consistently guard for less time than small males. The changes in female behaviour are consistent with the female's need to avoid the costs of guarding and suggest that females influence how pre-copulatory mate guarding occurs in this species.Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Tibial coloration, fluctuating asymmetry and female choice behaviour in the damselfly Platycypha caligata.

The territorial damselfly Platycypha caligata (Odontata: Chlorocyphidae) has a courtship behaviour where males wave the white anterior surface of all six laterally enlarged tibiae at females. I experimentally altered this white tibial surface using black paint to determine the effect on male behaviour of a 25% reduction in area, or an increase in asymmetry between the left and right side of the body. I collected behavioural data on courtship, mating and fighting for males already holding territories. Neither a reduction in the area nor an increase in asymmetry of tibial whiteness affected male mating rate, courtship rate or fighting behaviour. These manipulations also had no significant effect on the daily presence at the study site. Males whose tibial whiteness was experimentally removed also showed no decrease in mating rate or change in fighting behaviour while territorial. The complete removal of tibial whiteness did, however, lead to a significant reduction in daily presence, possibly due to a reduced ability to acquire or hold a territory. There was no relationship between natural levels of asymmetry in tibial whiteness and mating rate, courting rate or fighting behaviour for males with territories. However, the natural area of tibial whiteness was significantly positively related to both mean male mating rate and copulation duration for territorial males. This result suggests that a phenotypic correlate of area of tibial whiteness, probably body size, is sexually selected through female choice among males that already hold territories.Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Lifetime mating opportunities and male mating behaviour in sexually cannibalistic praying mantids.

I examined the number of lifetime mating opportunities and mating behaviour of males in two sexually cannibalistic species, the Mediterranean, Iris oratoria, and bordered, Stagmomantis limbata, praying mantids (Mantodea: Mantidae). Two approaches estimated the number of lifetime mating opportunities: direct observations of intersexual encounters in the field, and an encounter model. I collected behavioural observations, together with ecological data for use in the model, over three field seasons. The ecological data included an assessment of the feeding condition of S. limbata females in nature; the females fed at a level comparable to females maintained on an abundant diet in the laboratory. As for the number of mating opportunities, individual males of both species encountered two or more females, as predicted by the model. I observed no male, however, in more than one copulation. This result could reflect individual variation in the times and places of sexual activity or an actual low number of mating opportunities in the field. Furthermore, a higher percentage of I. oratoria males encountered two or more females than S. limbata males, as the model indicates. Fewer mating opportunities could lead to greater selection upon S. limbata males to ensure paternity at each mating, which can explain the longer copulation times observed for S. limbata males. I considered two hypotheses about male behaviour in light of the number of lifetime encounters with females: male suicide and male reduction of the risk of cannibalism. Behavioural observations do not strongly support male suicide in either species. Certain male behaviours, such as the nature of copulatory position and, in captivity, mounting females from the rear, are consistent with the idea that males behave so as to reduce the probability that they are cannibalized during intersexual encounters. Moreover, male I. oratoria preferentially mount well-fed, fecund females in captivity. Taken together, these results suggest that the prospect of multiple mating opportunities has influenced male mating behaviour over evolutionary time. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

The influence of tail autotomy on agonistic behaviour in a territorial salamander.

Assessment of potentially asymmetrical characters (such as fighting ability and resident advantage) is often important in determining the outcome of agonistic interactions. Loss of body parts, a predator defence mechanism used by many animals, may lead to a reduction in fighting ability and may be easily assessed by competitors. We investigated the influence of tail loss on the expression of agonistic behaviour in the territorial red-backed salamander, Plethodon cinereus. Residents and intruders were matched for body size, and pairs were tested in all combinations of tailed or tailless residents with tailed or tailless intruders. Neither residents nor intruders altered their behaviour based on their own tail condition, but they did alter their behaviour based on the tail condition of their opponents. Intruders showed more aggression or less submission towards tailless residents than towards tailed residents. When contests were between residents and intruders of the same tail condition (both tailed or tailless), intruders were more aggressive towards residents when both were tailless than when both were tailed, indicating that tail loss does not directly hamper aggressive displays. In contests where the asymmetry between residents and intruders was small (based on tail condition and residency status), intruders showed more aggression and less submission than in contests where the asymmetry was large. Residents did not differ in their behaviour for most comparisons. Thus, for intruders, the tail condition of residents is an important determinant of agonistic behaviour displayed in territorial contests. For residents, factors other than tail condition (such as resource value) may be more likely to influence their behaviour. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Fighting behaviour, vigilance and predation risk in the cichlid fish Nannacara anomala.

I studied the fighting behaviour of a small South American cichlid fish, Nannacara anomala, in relation to predation risk. In this species, which reduces vigilance during escalated fighting, differences in fighting ability are most accurately assessed during mouth wrestling. Thus, there is a potential trade-off between agonistic behaviours that are effective for assessing differences in fighting ability between contestants and agonistic behaviours that minimize the risk of being killed by predators. I investigated whether breaks between bouts of mouth wrestling improved the contestants' ability to flee from an approaching model fish predator. During the breaks between mouth wrestling the contestants had a significantly longer escape distance than males that were actively mouth wrestling. Fighting males also changed their fighting behaviour after the introduction of the model predator compared with males that were not exposed to it. Low-intensity behaviours such as lateral display and tail beating were preferred to mouth wrestling. In addition, both the number and duration of bouts of active mouth wrestling decreased significantly after the introduction of the model predator while the duration of the breaks between bouts of active mouth wrestling increased significantly compared with the control. Including predation risk in the costs of intense fighting may increase our understanding of both the temporal structuring of fighting behaviour and the evolution of fighting behaviour in general.1998 The Association for the Study of Animal Behaviour

Journal Article↗
PubMed1999

Suckling behaviour does not measure milk intake in horses, Equus caballus.

Studies of parental investment in mammals have frequently used suckling behaviour to estimate energy transfer from mother to offspring, and consequently to measure maternal input. Such studies assume that the more an offspring sucks, the more milk it will receive. This assumption has been questioned, and a review of the literature found little support for it. To test if suckling behaviour provided an accurate index of milk or energy intake we used a radioactive isotope technique to label the milk of thoroughbred mares and to measure milk transfer to foals. We found no significant linear relationship between usual measures of suckling behaviour and milk or energy intake. No behaviours associated with suckling nor with characteristics of mares and foals improved the relationship; only the number of butts associated with each suck episode even approached significance. If we had used suckling behaviour to test theories on differential maternal investment our conclusions would have been in error. For example, female foals tended to suck for longer than males did but there was no difference in the amount of milk transferred. Consequently, we show that measures of suckling behaviour do not adequately predict milk intake in the domestic horse and we suggest that conclusions about differential maternal investment in mammals based on suckling behaviour are likely to be in error. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

The role of food distribution and nutritional quality in behavioural phase change in the desert locust.

The behaviour of herbivorous insects is influenced by their nutritional state. Nutrition-induced behavioural changes are often interpreted as adaptive mechanisms for controlling nutrient intake; however, their influence on other life history traits has received far less attention. We investigated the effect of food quality and distribution on the behaviour and phase state of desert locusts, Schistocerca gregaria Forskål (Orthoptera, Acrididae), which change from the 'solitarious' to the 'gregarious' phase in response to population density. Phase change involves many morphological, physiological and behavioural changes. Solitarious insects are cryptic whereas gregarious locusts aggregate. Individual phase change is stimulated by mechanical contact with other locusts. A clumped resource distribution promotes change to the gregarious phase by increasing crowding and contact between individuals. In this study, we found that the effect of food distribution on locust phase depended on the nutritional quality of the food. We used three synthetic food treatments: near optimal, dilute and a choice of two unbalanced but complementary foods. Clumped resource distribution led to increased gregarization in the dilute and the complementary diet treatments. This effect was particularly pronounced on the complementary foods, owing to the interaction of crowding and locomotion. Gregarization was most pronounced in the dilute diet treatment, owing to increased activity. These diet-induced effects are explained in terms of behavioural changes in locomotion, quiescence and feeding that are consistent with what is known from earlier work on locust feeding behaviour and behavioural phase change. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1987

Assessment of grooming and other behavioural responses to the D-1 dopamine receptor agonist SK & F 38393 and its R- and S-enantiomers in the intact adult rat.

The behavioural effects of the D-1 dopamine receptor agonist SK & F 38393 were assessed in the intact adult rat using a conventional stereotypy rating scale and a rapid time sampling behavioural check list procedure. This combination technique allowed description of the nature of any behavioural response and quantification of the number of counts of individual behaviours. Using this combined procedure, SK & F 38393 clearly failed to induce typical stereotyped behaviour. However, in the well-habituated animal, SK & F 38393 dose-dependently increased the number of recordings of non-stereotyped sniffing, locomotion and grooming; some occasional rearing was also noted. An unusual pattern of intense grooming behaviour was a characteristic response to this drug. Using the resolved R- and S-enantiomers of SK & F 38393, promotion of sniffing, locomotion, rearing and grooming resided stereoselectively in the R-configuration. Under appropriate experimental conditions, specifically a requirement for prolonged habituation and the use of a rapid sampling behavioural check list to supplement the rating scale, it is possible to demonstrate that SK & F 38393 is behaviourally active in the whole animal.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1978

Hypothalamically induced intraspecific aggressive behaviour in the rat.

The effects of electrical stimulation of the lateral hypothalamus (LH) of rats on intraspecific aggressive behaviour were studied. In order to investigate the specificity of the stimulation effects, each experimental animal was stimulated in a number of different social situations. Stimulation of the LH in the presence of a subordinate male increased the amount of time spent on aggressive behaviour patterns and locomotion. In the presence of a dominant male, however, the stimulated animal never initiated a fight, whereas in the presence of an estrous female attack occurred in some rare occasions and sexual behaviour disappeared almost entirely. Stimulation of some sites also elicited mouse killing behaviour. Many of the electrodes that elicited intraspecific aggressive behaviour also supported intracranial self-stimulation. It is concluded that 1. electrical stimulation of this area of the LH predominantly potentiates intraspecific aggressive behaviour, 2. that this behaviour becomes overt depends on the external situation, including the behaviour of the opponent.

Aggression↗
PubMed1994

Behavioural actions of prolactin locally applied into the hippocampus of adult female rats.

The probable behavioural effects of rat prolactin (rPRL) locally applied into the ventral hippocampus (HPC) were studied in cycling female rats. Three experiments were performed examining the behavioural responses of rats subjected to three different situations: (i) Exploratory activity in an enriched holeboard (ii) exploratory activity under conflicting situation and (iii) escape behaviours in a forced swimming test. Behavioural parameters studied were: underground and object-directed exploration and locomotion (Experiment 1); latency time and exploration behaviours (Experiment 2); swimming time and escape behaviours (Experiment 3). In Experiment 1 results showed that rPRL decreased the underground exploration and also locomotion but increased the object-directed exploration and had no effect on non-ambulatory activity. In Experiment 2 results showed that treatment of rPRL increased the latency time but did not modify the exploratory activity. In Experiment 3 results showed that rPRL augmented the swimming time and one of two parameters (frequency of immersions intents) of the escape behaviour. Results are interpreted as local actions of PRL on hippocampal neuron affecting expression of behaviours of rats depending on the stressful conditions of the environment.

Animals↗
PubMed1995

Identification of behaviour profiles with a population of autistic children using multivariate statistical methods.

The Revised Behaviour Summarized Evaluation Scale (BSE-R) was developed for the objective evaluation of autistic behaviours in order to facilitate the recording of the evolution of developmentally disabled children. Among its 29 items, 13 items that precisely describe the degree of autistic behaviours were extracted by Principal Component Analysis. We hypothesised that these relevant behaviours could differentiate autistic behaviour profiles in a population of children previously diagnosed as typically autistic. For this purpose, we used an original multivariate descriptive statistical approach, Correspondence Analysis, which can help in detecting structural relationships among variables. In a population of autistic children initially diagnosed using DSM-III-R criteria, this procedure proved effective in identifying new main dimensions of behaviours among the 13 previously defined core autistic symptoms. Cluster analysis, which followed factorial analysis, allowed the identification of three meaningful behaviour profiles separated principally on the basis of two main functions, perception and imitation, which have been always considered to be fundamentally involved in autistic syndrome. The individualisation of homogeneous subgroups of children on the basis of the behavioural evaluation provides a potentially useful starting point for further biological and therapeutic studies.

Autistic Disorder↗
PubMed1991

Behavioural profile of partial D2 dopamine receptor agonists. 1. Atypical inhibition of d-amphetamine-induced locomotor hyperactivity and stereotypy.

The effects of partial D2 dopamine (DA) receptor agonists on the behavioural activation produced by 1.5 and 8.0 mg/kg d-amphetamine were compared with the changes produced by the classical DA antagonist haloperidol. Alterations in behaviour were assessed in standard activity monitoring cages by direct observation of the rats using a rapid time sampling procedure. Haloperidol blocked d-amphetamine (1.5 mg/kg)-induced increases in photocell counts, ambulation, rearing and sniffing up, and after the highest dose of the DA antagonist the animals were mainly inactive. The partial D2 DA agonist SDZ 208-911 was equipotent to haloperidol in blocking the increase in photocell counts and rearing produced by d-amphetamine. However, even high doses of the drug did not reduce the incidence of sniffing or induce inactivity, but qualitative changes in the form of sniffing did occur. Although considerably less potent, preclamol exerted similar effects to SDZ 208-911. The profiles of SDZ 208-912 and terguride were intermediary to those of SDZ 208-911 and haloperidol. All compounds blocked the repetitive sniffing down produced by 8.0 mg/kg d-amphetamine. After a low dose of haloperidol, these stereotyped behaviours were replaced by a behavioural syndrome similar to that observed with low dose d-amphetamine, but inactivity was observed following a further small increase in antagonist dose. The blockade of stereotypy by SDZ 208-911, preclamol and terguride was accompanied only by the low dose d-amphetamine behavioural syndrome; no inhibition of sniffing or induction of inactivity occurred. SDZ 208-912 exhibited a profile with features very similar to that noted with haloperidol. These findings suggest that partial D2 agonists exert similar, but not identical, behavioural effects to classical DA antagonists when dopaminergic function in increased by d-amphetamine. The differences in behavioural profile are discussed in relation to variations in the intrinsic efficacy of the dopaminergic compounds and to differences in the response capability of D2 receptor populations underlying the different behaviours produced by d-amphetamine.

Animals↗
PubMed1990

Repeated ECS enhances dopamine D-1 but not D-2 agonist-induced behavioural responses in rats.

The present study examined the effect of acute and repeated administration of electroconvulsive shock (ECS) on behaviours induced by various dopamine agonists in rats. Components of behavioural arousal induced by the dopamine D-1 agonist SKF 38393, the dopamine D-2 agonist RU 24213 and the mixed D-1/D-2 agonist apomorphine were assessed using a behavioural check-list method. Also, the overall behavioural syndrome produced by these drugs was measured using rating scales. Rats receiving repeated (5 times over 10 days) but not a single ECS showed enhanced grooming and sniffing in response to SKF 38393 (7.5 mg/kg) when compared to controls. Repetitive sniffing induced by apomorphine (0.5 mg/kg) was also enhanced by repeated ECS. Neither repeated nor a single ECS significantly changed behaviours induced by RU 24213 (0.75 mg/kg), although a downward trend was evident. The behaviour rating scale measurements also demonstrated that repeated administration to ECS increased behavioural responsiveness to SKF 38393 and apomorphine but not RU 24213. These results suggest that the increase of dopamine-mediated behaviour in rats seen after chronic ECS relates to an increase in central dopamine D-1 receptor function.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1995

Comparative behavioural and neurochemical studies with a psychomotor stimulant, an hallucinogen and 3,4-methylenedioxy analogues of amphetamine.

Spontaneous behaviours were assessed in freely moving rats after treatment with equimolar doses of drugs that share a basic amphetamine structure. The drugs used included a psychomotor stimulant [(+)-amphetamine (AMPH)], an hallucinogen [para-methoxyamphetamine (PMA)] and the entactogens 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDE). A detailed analysis of the frequency and duration of 30 different behaviours and the temporal organization of the behaviours was conducted in addition to measuring motor activity with an automated device. Levels of the biogenic amines and their acid metabolites in discrete brain regions and brain drug levels were also obtained. The automated motor activity measures discriminated among entactogens, the stimulant and the hallucinogen, but failed to distinguish between the hallucinogen and vehicle. Principal components analysis and cluster analysis of the frequencies and durations of the behaviours did not improve the classification of the drugs over the automated motor activity measures. Only the cluster analysis of the transitions between individual behaviours succeeded in differentiating the drug classes from each other and from vehicle treatment. All the behavioural measures classified one entactogen (MDE) as an hallucinogen. Cortical 5-hydroxytryptamine (5-HT) measures grouped MDE with the other entactogens but did not distinguish AMPH from vehicle. However, striatal dopamine measures differentiated AMPH from vehicle treatment. Variations in the durations of behavioural effects across drugs were associated with large differences in drug levels 3 h after injection. Although the neurochemical data provided a classification system that most closely parallels human subjective effects of these drugs, both the neurochemical and the behavioural measures supported the existence of an entactogen class distinct from a psychomotor stimulant and an hallucinogen.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1998

Effects of dopamine agonists and antagonists on PCP-induced stereotyped behaviour and social isolation in the rat social interaction test.

Phencyclidine (PCP) can induce a model psychosis in humans that resembles an acute schizophrenic psychosis. In animal models of schizophrenia, PCP induces locomotor hyperactivity, stereotyped behaviour and social isolation, and the purpose of the present study was to describe the ability of dopamine agonists and antagonists to mimic or interact with these PCP-induced behaviours in rats. The compounds were administered daily for 3 days in combination with vehicle or 2.0 mg/kg PCP and the rats were tested in the social interaction test on the last day of drug administration. The study showed that D1-agonists with relative differences in efficacy at the DA-stimulated adenylate cyclase had limited effects on the PCP-induced behaviours, whereas the D1-antagonist SCH 23391 could alleviate the PCP-induce social isolation following daily treatment for 3 days. However, following long-term treatment for 21 days, the rats develop tolerance to this effect. These data thus suggested that the D1-receptor system only had a modulatory effect on PCP. In contrast, the D2-receptor family may be more directly involved, because the D2/D3/D4-agonist quinpirole could mimic and potentiate the PCP-induced deficits in social behaviour, and the D2/D3-antagonist (-)sulpiride could alleviate the PCP-induced stereotyped behaviour and social isolation. However, a D4-antagonist did not affect the behaviour of vehicle- and PCP-treated rats, suggesting that this system plays a less direct role in the behavioural effects of PCP. In general, however, the effects of SCH 23391, quinpirole and (-)sulpiride on the PCP-induced behaviours were mirrored in the vehicle-treated control groups and it is therefore possible that non-specific effects may have been important.

Animals↗