Effects of cannabis resin on social behaviour in the laboratory mouse

Prosocial Effects of Nonpsychotropic Cannabis sativa in Mice

Introduction:Cannabis sativa L. (C. sativa) is used since ancient times to produce fabrics, baskets, and cords. Later, different ethnic groups used to burn the leaves and flowers of psychotropic cultivars with high Δ9-tetrahydrocannabinol (D9-THC) levels, during the religious or propitiatory rites to alter the state of consciousness. To date, it is not known whether also nonpsychotropic cultivars of C. sativa were used during these rites, and whether these varieties could have an effect on human behavior. This study aimed to evaluate the behavioral effects of an extract of nonpsychotropic C. sativa (NP-CS) in mice. Materials and Methods: An extract of a nonpsychotropic cultivar of C. sativa dissolved in medium-chain triglyceride oil was used and the different phytochemical components were evaluated. The relative composition in terms of phytocannabinoid content was assessed by reverse phase high-performance liquid chromatography coupled to UV detection (RP-HPLC-UV), and the volatile components were analyzed by gas chromatography-mass spectrometry (GC-MS). In addition, the behavioral effect of NP-CS was assessed on a wild-type mouse model. The animals were treated for 14 days (oral gavage) and motility, anxiety, and social effects were assessed. Results: RP-HPLC-UV analysis demonstrated that D9-THC was present in lower concentration with respect to other cannabinoids, like cannabidiol. Furthermore, the GC-MS analysis revealed the presence of several terpenoids. Concerning in vivo studies, chronic treatment with NP-CS did not alter body weight, motility, and anxiety and increased social interaction. Conclusions: This study highlighted the prosocial effects of NP-CS.

Determination of naphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-018) in mouse blood and tissue after inhalation exposure to 'buzz' smoke by HPLC/MS/MS

The disposition of the cannabimimetic naphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-018) in mice following inhalation of the smoke of the herbal incense product (HIP) 'Buzz' is presented. A high-pressure liquid chromatography with electrospray ionization triple quadrupole mass spectrometer (HPLC/MS/MS) method was validated for the analysis of JWH-018 in the specimens using deuterated Δ(9) -tetrahydrocannabinol (d(3) -THC) as the internal standard. JWH-018 was isolated by cold acetonitrile liquid-liquid extraction. Chromatographic separation was performed on a Zorbaz eclipse XDB-C(18) column. The assay was linear from 1 to 1000 ng/mL. Six C57BL6 mice were sacrificed 20 min after exposure to the smoke of 200 mg 'Buzz' containing 5.4% JWH-018. Specimen concentrations of JWH-018 were: blood, 54-166 ng/mL (mean 82 ± 42 ng/mL); brain, 316-708 ng/g (mean 510 ± 166 ng/g); and liver, 1370-3220 ng/mL (mean 1990 ± 752 ng/mL). The mean blood to brain ratio for JWH-018 was 6.8 and ranged from 4.2 to 10.9. After exposure, the responses of the mice were consistent with cannabinoid receptor type 1 activity: body temperatures dropped 7.3 ± 1.1 °C, and catalepsy, hyperreflexia, straub tail and ptosis were observed. The brain concentrations and physiological responses are consistent with the hypothesis that the behavioral effects of 'Buzz' are attributable to JWH-018.

Pharmacological evidence for a role of D2 dopamine receptors in the defensive behavior of the mouse

In this study the role of the DA system in the expression of defensive behavior of the mouse was investigated. C57BL/6 mice subjected to three daily defeat experiences (24 h apart) exhibited an increase of defensive behaviors (upright and sideways postures and escape) as well as a decrease of activity and a decrease of social investigation compared with undefeated mice (controls) when confronted with nonaggressive Swiss mice 24 h after the last aggressive confrontation. The selective D2 DA receptor antagonist (-)-sulpiride administered before confrontation with nonaggressive opponents (fourth day) dramatically decreased defensive behaviors and produced an increase of social investigation. The selective D1 DA receptor antagonist SCH 23390 did not affect either defence or social investigation. In further experiments the behavioral effects of the selective D1 agonist SKF 38393 and of the selective D2 agonist LY171555 on naive C57BL/6 mice interacting with nonaggressive opponents of the same strain were assessed. SKF 38393 in doses up to 30 mg/kg did not produce any significant behavioral changes while LY171555 produced a clear-cut dose-dependent increase of defensive behavior as well as a decrease of social investigation and activity and an increase of immobility. The behavioral profile produced by the D2 agonist did not differ from that produced by defeat experiences. These results indicate that D2 receptors play a major role in the expression of defensive behavior in the mouse. The hypothesis that alteration in D2 receptor functioning may produce hyperdefensiveness possibly due to altered perceptive processes is discussed.

Emergence and development of stress-induced analgesia and concomitant behavioral changes in mice exposed to social conflict

Mice of the inbred strain DBA/2, when exposed to a social conflict, developed a low intensity, naloxone-insensitive analgesia after 15 bites, and a more pronounced naloxone-sensitive analgesia after 45 bites. The effective inhibition of the antinociceptive response following low and high number of bites by the alkylating opiate antagonist beta-chlornaltrexamine suggests participation of opioid mechanisms at both stress levels. Emergence of an increased tail-flick latency was indicated by the occurrence of defensive upright postures upon contact with the opponent, while animals displaying full analgesic response during the period of bite 31-45 increased their escape reactions without being in contact with the aggressor. Suppression of social conflict analgesia in mice by pretreatment with opiate antagonists facilitated the occurrence of these escape reactions. The display of panic escape responses is discussed in the context of increased fear and helplessness that developed under conditions of sustained attacks.

Effects of repeated as compared to single aggressive confrontation on nociception and defense behavior in C57BL/6 and DBA/2 mice

Behavioral reactions (submissive postures, escape, immobility, activity, locomotion) in C57BL/6 and DBA/2 test mice were recorded during single (50 bites) or three repeated (3 X 50 bites, separated by 24 hr) aggressive confrontations, as well as during a nonaggressive confrontation 24 hr after the last aggressive confrontation with opponents of the opposite strain. Nociception (hot plate response latency) was measured 1 min after aggressive or nonaggressive confrontations. During repeated aggressive confrontation, DBA mice reacted with a stable pattern of escape and analgesia, whereas C57 mice failed to develop an analgesic response and changed their behavioral defense strategy during repeated aggressive confrontations (decrease of escape, increase of defensive upright). The conditioned display of submission and of escape behavior during nonaggressive confrontation did not change as a function of earlier repeated aggressive confrontations in DBA mice, while C57 mice showed a significant increase of defensive upright postures and immobility. Conditioned analgesia was not observed after nonaggressive confrontations. The results point toward a dissociation between attack-elicited behavior and antinociception and suggest that encounter-induced analgesia may influence the processing of aversive experience.

Hashish extract impairs retention of defeat-induced submissive behavior in mice

The effects of hashish extract on adaptive behavior of male mice were studied in a paradigm which allows the investigation of learning mechanisms in a social context. Mice of the C3H strain, which were not submissive in a confrontation with a nonaggressive DBA mouse on day 1, were defeated on day 2 over 3 min by aggressive, isolated DBA mice, and showed conditioned submissive behavior upon mere contact with a nonaggressive DBA mouse on day 3. A hashish extract containing 38.6-39.4% delta 9-tetrahydrocannabinol (delta 9-THC), 11.6-12.0% cannabinol and 47.7-48.5% cannabidiol was administered orally in all experiments. Hashish extract given 90 min before defeat on day 2, in dosages corresponding to 1, 5, and 10 mg delta 9-THC/kg, impaired retention of defensive upright, defensive sideways and immobility on day 3 (experiment 1). Experiment 2 showed that the drug (5, and 10 mg delta 9-THC/kg) had no antinociceptive potency in mice and did not modify defeat-induced analgesia. Experiment 3, with drug (5 mg delta 9-THC/kg) or solvent administration on day 2 and day 3, showed that the retention deficit was neither due to state-dependent learning, nor to impaired retrieval. It is suggested that hashish extract administered before learning may interfere with memory processing.

Cannabis and delta-9-tetrahydrocannabinol. Effects on elements of social behaviour in mice

Behavioural effects of cannabis and delta-9-tetrahydrocannabinol (THC) in male mice encountering solvent-treated males, and of cannabis in males encountering control females, were examined by ethological procedures. Effects on elements and element-groups within behavioural categories were investigated, and effects of cannabis on the response sequence to the behaviour of male partners examined. Effects were detected on elements that previously had been grouped within categories. Flight elements "flag, evade, retreat and flee" and immobility were increased both by cannabis (50 and 100 mg/kg in male-male encounters and 25 mg/kg in male-female encounters) and by THC (5 mg/kg), whereas "scan", "wash and self-groom" and some elements of social investigation were reduced. Bout length and duration of "explore" were increased by THC. In encounters with females, cannabis decreased sexual behaviour. Sequence analysis showed that cannabis, within the limitations of the comparatively small size of sample, to have no significant effect upon normal behavioural responses at 50 and 100 mg/kg, apart from enhancement of the flight response to aggression and some elements of social investigation by partners. These more detailed analyses revealed effects that would not be detectable by the conventional approach.

Alcohol increases both locomotion and immobility in mice: an ethological analysis of spontaneous motor activity

The effects of alcohol on locomotor activity of group- and individually-housed mice were studied using direct ethological observations, including a detailed postural analysis and measures of both locomotion and immobility. Ethanol (0, 0.5, 1.0 and 2.0 g/kg, IP) was given to subjects placed alone in a novel cage, and videotape recordings of behaviour were made. Locomotor activity was unchanged or increased by alcohol administration. Immobility was profoundly increased, however, at both the intermediate and high doses of alcohol, so that there was a simultaneous increase in measures of both locomotion and immobility. These increases were possible because of a decrease in certain active but non-locomotor elements of behaviour, such as rearing and digging. There generally appeared to be little effect of differential housing, although blood alcohol levels were significantly higher in group-housed animals. This depressant effect of alcohol would probably not be detected by simply recording locomotor activity, since ambulation itself was unchanged or increased. Measurements of both locomotion and immobility may thus more accurately detect stimulant and depressant effects of drugs.

Effects of multiple, chronic and early hashish exposure on mating behavior, nest-building and gestation in mice

1. The effects of hashish extract on social behavior were investigated in pairs of mice living together from mating to parturition. The drug was administered orally to both animals at a dose of 20 mg delta 9-tetrahydrocannabinol/kg three times a week, either (I) during the 3 weeks from mating to parturition, (II) during the 12 weeks from weaning to mating and parturition, or (III) only during the 3 weeks after weaning. 2. In the mating tests, an acute administration (I) caused a general sedation. Chronically treated animals (II) showed decreased sexual behavior and lower social investigations despite significantly more non-social activities. Early drug treatment (III) had no effect on mating behavior. In all three series of experiments the females had conceived by the next morning. 3. The nest-building behavior during pregnancy was suppressed after multiple (I) and chronic (II) drug administration. In early drug-treated animals (III) the transport of nesting material was only slowed down. Non-social activities were normal or increased in all three series. 4. Parturition was significantly delayed by one day after multiple (I) and chronic (II) drug administration. The birth weight was not affected, but the litter size was decreased after chronic drug treatment. Early drug administration (III) had no effects on these parameters. 5. In conclusion, whereas tolerance to the sedative effects of hashish developed very rapidly, the drug influences on social behavior were stable. Therefore, discussions on legalization of cannabis should pay attention to the drug effects on social behavior.

Behavioural effects of hashish in mice in comparison with other psychoactive drugs

1. The behavioural effects of hashish extract (10 mg delta 9-THC/kg) were compared to those of morphine (20 mg/kg), diazepam (10 mg/kg), imipramine (10/kg), amphetamine (10 mg/kg) and chlorpromazine (10 mg/kg) by testing male mice in a resident-intruder situation. 2. The drugs were given either to the resident or to the intruder male. 3. Hashish extract similar to diazepam and chlorpromazine reduced social activities in resident and intruder males. 4. Intruder males treated with hashish or diazepam were more frequently attacked and submission and light was increased. 5. Amphetamine and morphine stimulated locomotion and non-social activities but impaired social behaviour especially in residents. 6. Imipramine increased aggressive behaviour in resident and intruder males.

A novel female influences delta 9-THC effects on plasma hormone levels in male mice

Exposure to delta 9-tetrahydrocannabinol (THC) (50 mg/kg) alters the endocrine responsivity of male mice to female-related exteroceptive stimuli. Exposure to a novel female prevents or delays the THC-induced decrease in plasma testosterone (T) and luteinizing hormone (LH) levels. These hormonal alterations are apparently not due to the LH-releasing effects of female-related pheromonal or tactile cues, since administration of luteinizing hormone releasing factor (LRF) did not mimic the effects of a novel female on plasma T levels in THC-treated males. Exposure to a much lower dose of THC (0.5 mg/kg) did augment the LRF-induced increases in plasma T levels suggesting a possible synergism between gonadotropins and THC on androgen production. The present findings suggest that THC-induced alterations in hormonal status may be influenced by complex social or environmental factors.

Delta-9-Tetrahydrocannabinol stimulates receptive and proceptive sexual behaviors in female hamsters

This experiment studied the effects of delta-9-tetrahydrocannabinol (THC) on lordosis responses and ultrasonic communication (measures of sexual receptivity and proceptivity, respectively) in female hamsters. Specifically, lordosis durations and rates of ultrasound production by estradiol-primed ovariectomized hamsters were observed following acute treatment with 1.5 mg/kg of THC, 500 micrograms of progesterone, or the injection vehicle. The results showed that THC can facilitate both lordosis and ultrasound production. Together with results from other laboratories, these data indicate that THC can stimulate female sexual behavior and suggest that this effect reflects a direct, nonhormonal, effect of THC on brain mechanisms for behavior.

Behavioral effects of hashish in mice. I. Social interactions and nest-building behavior of males

The acute and subchronic effects of hashish extract (20 mg delta 9-THC/kg) on the behavior of male mice encountering a control partner was studied by ethological methods. A single administration of the extract resulted in general sedation, suppressing all the individual and social activities with the exception of some submissive elements. The locomotive and the overall activity of drugged males was drastically reduced and immobility occurred frequently. After four applications, tolerance to the sedative effects had developed and behavioral drug effects were recognizable. Drugged males showed an increase in nonsocial activities as well as in submissive behavior and flight, whereas social investigation was less frequent. Sexual and aggressive behavior was not significantly affected by the drug and immobility no longer occurred. In spite of behavioral changes after a single or repeated drug treatment, drugged males became dominant in about half the experiments. The nest-building behavior of males was disturbed in the same way after one or four drug applications. Drugged males generally refrained from carrying and working up the nesting material. The acute behavioral effects of hashish extract are compared to those described in previous papers and the difference between acute and subchronic drug effects is discussed.

Behavioral effects of hashish in mice. III. Social interactions between two residents and an intruder male

The acute and subchronic effects of hashish extract (20 mg delta 9-THC/kg) on the social interactions between two drug-treated residents and an untreated intruder male were investigated. In this analysis 28 different behavioral elements were recorded. A single drug application suppressed all categories of behavior, except submissive behavior and flight, in dominant and subordinate residents. Treated animals were less active than controls and immobility was very frequent. An elevated total activity, due to an increase in non-social activities, was observed in the untreated intruder males of this group. Social investigation as well as submissive behavior and flight were reduced in these animals. On introduction of an untreated male after the fourth drug treatment of the residents, the drugged males showed tolerance to the sedative and most of the other behavioral effects of the drug, and intruder males behaved quite normally. The formation of a dominant-subordinate relation within the group was influenced neither by a single nor by repeated drug treatment. The acute and subchronic effects of hashish extract on social, especially aggressive behavior of males are compared to those described in previous papers and the variation in the results of the different studies is discussed.

Effects of ethyl alcohol on development and social behaviour in the offspring of laboratory mice

Behavioural and developmental effects of exposure to a low level of ethyl alcohol from conception to adulthood have been examined in mice. A 5% solution of alcohol in the drinking fluid of male and female adults did not impair fertility. The offspring of treated mice were significantly lighter at birth than their controls and remained so throughout their life span. No congenital malformations were observed. Behaviour of the offspring 3--4 weeks of age and in adulthood was examined by ethological analysis of encounters between alcohol-treated and control mice of the same sex. In male and female juvenile mice receiving 5% alcohol, the frequency and duration of social investigation were significantly lower than those of control partners and the duration of non-social behaviour was raised. Individual elements of 'investigate' and 'sniff' were significantly reduced in frequency. In alcohol-treated adults, the only behavioural difference from controls was an increased frequency of flight elements occurring in males. It is suggested that long-term exposure to alcohol may lead to behavioural adaptation.

Effects of delta9-tetrahydrocannabinol on social behaviour in mice: comparison between two vehicles

Two vehicles for the intraperitoneal administration of delta9-tetrahydrocannabinol (delta9-THC) were compared, using aspects of social behaviour in mice and 5 doses of delta9- THC, with vehicle alone and saline control groups. 10% propane-1,2-diol-1% Tween 80-saline (vehicle B) seemed to be more effective than 1% Tween 80-saline (vehicle A) since depressant effects of --1 delta9-THC on behaviour tended to occur at lower doses with this vehicle. Few differences in behaviour could be detected among the three control groups. In general the overall number of behavioural acts decreased with increasing doses of delta9-THC, but with vehicle B low doses selectively decreased the number of 'social' (including aggressive) as distinct from 'individual' acts. Low doses of the drug in vehicle A sometimes stimulated behaviour, whereas with vehicle B such doses mostly produced depression; however, 2.5 mg/kg delta9-THC, in either vehicle, markedly increased the percentage of animals which showed both aggression and flight acts--a rare combination among controls. Our findings are consistent with other evidence that propylene glycol is an effective vehicle for the i.p. administration of delta9-THC.

Effects of delta-9-tetrahydrocannabinol on social behaviour in the laboratory mouse and rat

The behavioural effects of delta-9-tetrahydrocannabinol in mice and rats have been studied by an ethological analysis of encounters between animals injected with the drug and partners injected with the solvent (Tween-saline). In both species, Immobility was increased and Non-Social Activity reduced after injections of 5 mg/kg of delta-9-tetrahydrocannabinol. Flight was increased in treated mice but not in treated rats. Aggression was not significantly altered in either species. Thus, in the mouse, the qualitative behavioural effects of delta-9-tetrahydrocannabinol were similar to those previously reported for crude cannabis resin. Comparison of the dose-response data indicated that some other constituents of cannabis may reduce the Flight reaction from delta-9-tetrahydrocannabinol although not interfering with Immobility.

Behavioural changes in laboratory mice during cannabis feeding and withdrawal

The effects of feeding cannabis at a level of 0.4% in the diet has been studied by an ethological analysis of encounters between male mice. Administration of cannabis to dominant males resulted in a reduction of non-social activity and an increase in flight and in social and sexual investigation when compared with untreated controls, but the behaviour of subordinate males was not significantly altered by cannabis. One week after withdrawal of cannabis, the behaviour of diminant males showed a rebound effect with increase in aggression. Nevertheless, by a preference feeding test it was demonstrated that the treated mice were not dependent on the cannabis-containing diet but consumed the control diet in preference.