A follow-up study: acute behavioural effects of Δ9-THC in female heterozygous Neuregulin 1 transmembrane domain mutant mice (original) (raw)
Related papers
2013
Heavy cannabis abuse increases the risk of developing schizophrenia. Adolescents appear particularly vulnerable to the development of psychosis-like symptoms after cannabis use. To test whether the schizophrenia candidate gene neuregulin 1 (NRG1) modulates the effects of cannabinoids in adolescence, we tested male adolescent heterozygous transmembrane domain Nrg1 mutant (Nrg1 TM HET) mice and wild type-like littermates (WT) for their neurobehavioural response to repeated D 9 -tetrahydrocannabinol (THC, 10 mg/kg i.p. for 21 d starting on post-natal day 31). During treatment and 48 h after treatment withdrawal, we assessed several behavioural parameters relevant to schizophrenia. After behavioural testing we measured autoradiographic CB 1 , 5-HT 2A and NMDA receptor binding. The hyperlocomotor phenotype typical of Nrg1 mutants emerged after drug withdrawal and was more pronounced in vehicle than THC-treated Nrg1 TM HET mice. All mice were equally sensitive to THC-induced suppression of locomotion. However, mutant mice appeared protected against inhibiting effects of repeated THC on investigative social behaviours. Neither THC nor Nrg1 genotype altered prepulse inhibition. Repeated adolescent THC promoted differential effects on CB 1 and 5-HT 2A receptor binding in the substantia nigra and insular cortex respectively, decreasing binding in WT while increasing it in Nrg1 TM HET mice. THC also selectively affected 5-HT 2A receptor binding in several other regions in WT mice, whereas NMDA receptor binding was only affected in mutant mice. Overall, Nrg1 mutation does not appear to increase the induction of psychotomimetic symptoms by repeated adolescent THC exposure but may attenuate some of its actions on social behaviour and schizophrenia-relevant neurotransmitter receptor profiles.
Using Knockout Mice Models to Explore Links between THC and Schizophrenia: A Research Protocol
2019
The legalization of marijuana in Canada raises many concerns regarding its consequences on the central nervous system. From being widely used as a medicinal remedy to now being used recreationally, this proposal aims to focus on an experiment that examines THC and its potentially detrimental effects on the brain, specifically in mice at-risk for schizophrenia. This proposal outlines a mouse model analysis of an analogue of THC that will be constructed using a knockout mice lineage in which the mice have a genetic predisposition to schizophrenia and lack the CB1 receptors responsible for binding THC. The resultant mice will undergo a grooming behaviour test and an elevated zero maze test which will then be compared with other experimental and control groups. This will allow for the direct observation of THC’s effects on the brain, providing insight on the consequences of the legalization of marijuana and its recreational use.
Distinct Neurobehavioural Effects of Cannabidiol in Transmembrane Domain Neuregulin 1 Mutant Mice
PLoS ONE, 2012
The cannabis constituent cannabidiol (CBD) possesses anxiolytic and antipsychotic properties. We have previously shown that transmembrane domain neuregulin 1 mutant (Nrg1 TM HET) mice display altered neurobehavioural responses to the main psychoactive constituent of cannabis, D 9 -tetrahydrocannabinol. Here we investigated whether Nrg1 TM HET mice respond differently to CBD and whether CBD reverses schizophrenia-related phenotypes expressed by these mice. Adult male Nrg1 TM HET and wild type-like littermates (WT) received vehicle or CBD (1, 50 or 100 mg/kg i.p.) for 21 days. During treatment and 48 h after withdrawal we measured behaviour, whole blood CBD concentrations and autoradiographic receptor binding. Nrg1 HET mice displayed locomotor hyperactivity, PPI deficits and reduced 5-HT 2A receptor binding density in the substantia nigra, but these phenotypes were not reversed by CBD. However, long-term CBD (50 and 100 mg/ kg) selectively enhanced social interaction in Nrg1 TM HET mice. Furthermore, acute CBD (100 mg/kg) selectively increased PPI in Nrg1 TM HET mice, although tolerance to this effect was manifest upon repeated CBD administration. Long-term CBD (50 mg/kg) also selectively increased GABA A receptor binding in the granular retrosplenial cortex in Nrg1 TM HET mice and reduced 5-HT 2A binding in the substantia nigra in WT mice. Nrg1 appears necessary for CBD-induced anxiolysis since only WT mice developed decreased anxiety-related behaviour with repeated CBD treatment. Altered pharmacokinetics in mutant mice could not explain our findings since no genotype differences existed in CBD blood concentrations. Here we demonstrate that Nrg1 modulates acute and long-term neurobehavioural effects of CBD, which does not reverse the schizophrenia-relevant phenotypes.
Genetic dissection of behavioural and autonomic effects of Delta(9)-tetrahydrocannabinol in mice.
Marijuana and its main psychotropic ingredient Delta(9)-tetrahydrocannabinol (THC) exert a plethora of psychoactive effects through the activation of the neuronal cannabinoid receptor type 1 (CB1), which is expressed by different neuronal subpopulations in the central nervous system. The exact neuroanatomical substrates underlying each effect of THC are, however, not known. We tested locomotor, hypothermic, analgesic, and cataleptic effects of THC in conditional knockout mouse lines, which lack the expression of CB1 in different neuronal subpopulations, including principal brain neurons, GABAergic neurons (those that release gamma aminobutyric acid), cortical glutamatergic neurons, and neurons expressing the dopamine receptor D1, respectively. Surprisingly, mice lacking CB1 in GABAergic neurons responded to THC similarly as wild-type littermates did, whereas deletion of the receptor in all principal neurons abolished or strongly reduced the behavioural and autonomic responses to the drug. Moreover, locomotor and hypothermic effects of THC depend on cortical glutamatergic neurons, whereas the deletion of CB1 from the majority of striatal neurons and a subpopulation of cortical glutamatergic neurons blocked the cataleptic effect of the drug. These data show that several important pharmacological actions of THC do not depend on functional expression of CB1 on GABAergic interneurons, but on other neuronal populations, and pave the way to a refined interpretation of the pharmacological effects of cannabinoids on neuronal functions.
Genetic Dissection of Behavioural and Autonomic Effects of Δ9-Tetrahydrocannabinol in Mice
2007
Marijuana and its main psychotropic ingredient Δ 9-tetrahydrocannabinol (THC) exert a plethora of psychoactive effects through the activation of the neuronal cannabinoid receptor type 1 (CB1), which is expressed by different neuronal subpopulations in the central nervous system. The exact neuroanatomical substrates underlying each effect of THC are, however, not known.
Neuropsychopharmacology, 2020
Δ 9-tetrahydrocannabinol (THC) is the intoxicating constituent of cannabis and is responsible for the drug's reinforcing effects. Retrospective human studies suggest that cannabis use during adolescence is linked to long-term negative psychological outcomes, but in such studies it is difficult to distinguish the effects of THC from those of coexisting factors. Therefore, translationally relevant animal models are required to properly investigate THC effects in adolescents. However, though the relevance of these studies depends upon human-relevant dosing, surprisingly little is known about THC pharmacology and its effects on behavior and brain activity in adolescent rodents-especially in females. Here, we conducted a systematic investigation of THC pharmacokinetics, metabolism and distribution in blood and brain, and of THC effects upon behavior and neural activity in adolescent Long Evans rats of both sexes. We administered THC during an early-middle adolescent window (postnatal days 27-45) in which the brain may be particularly sensitive to developmental perturbation by THC. We determined the pharmacokinetic profile of THC and its main first-pass metabolites (11-hydroxy-THC and 11-nor-9-carboxy-THC) in blood and brain following acute injection (0.5 or 5 mg/kg, intraperitoneal). We also evaluated THC effects on behavioral assays of anxiety, locomotion, and place conditioning, as well as c-Fos expression in 14 brain regions. Confirming previous work, we find marked sex differences in THC metabolism, including a female-specific elevation in the bioactive metabolite 11-hydroxy-THC. Furthermore, we find dose-dependent and sexdependent effects on behavior, neural activity, and functional connectivity across multiple nodes of brain stress and reward networks. Our findings are relevant for interpreting results of rat adolescent THC exposure studies, and may lend new insights into how THC impacts the brain in a sex-dependent manner.
Neurobehavioral effects of Δ 9THC and cannabinoid (CB1) receptor gene expression in mice
Behavioural Brain Research, 1995
The differential sensitivity following the administration of Δ9-THC to 3 mouse strains, C57BL/6, DBA/2 and ICR mice, indicated that some of the neurobehavioral changes may be attributable to genetic differences. The objective of this study was to determine the extent to which the cannabinoid (CB1) receptor is involved in the observed behavioral changes following Δ9-THC administration. This objective was addressed by experiments using: (1) DNA-PCR and reverse PCR; (2) systemic administration of Δ9-THC, and; (3) intracerebral microinjection of Δ9-THC. The site specificity of action of Δ9-THC in the brain was determined using stereotaxic surgical approaches. The intracerebral microinjection of Δ9-THC into the nucleus accumbens was found to induce catalepsy, while injection of Δ9-THC into the central nucleus of amygdala resulted in the production of an anxiogenic-like response. Although the DNA-PCR data indicated that the CB1 gene appeared to be identical and intronless in all 3 mouse strains, the reverse PCR data showed two additional distinct CB1 mRNAs in the C57BL/6 mouse which also differed in pain sensitivity and rectal temperature changes following the administration of Δ9-THC. It is suggested that the diverse neurobehavioral alterations induced by Δ9-THC may not be mediated solely by the CB1 receptors in the brain and that the CB1 genes may not be uniform in the mouse strains.
The international journal of neuropsychopharmacology / official scientific journal of the Collegium Internationale Neuropsychopharmacologicum (CINP), 2011
Cannabis increases the risk of schizophrenia in genetically vulnerable individuals. In this study we aim to show that the schizophrenia susceptibility gene neuregulin 1 (Nrg1) modulates the development of tolerance to cannabinoids in mice. Nrg1 heterozygous (HET) and wild-type (WT) mice were treated daily for 15 d with the synthetic analogue of Δ9-tetrahydrocannabinol, CP55,940 (0.4 mg/kg). We measured the impact of this exposure on locomotor activity, anxiety, prepulse inhibition (PPI), body temperature and FosB/ΔFosB immunohistochemistry. Tolerance to CP55,940-induced hypothermia and locomotor suppression developed more rapidly in Nrg1 HET mice than WT mice. Conversely in the light-dark test, while tolerance to the anxiogenic effect of CP55,940 developed in WT mice over days of testing, Nrg1 hypomorphs maintained marked anxiety even after 15 d of treatment. Repeated cannabinoid exposure selectively increased FosB/ΔFosB expression in the lateral septum, ventral part (LSV) of Nrg1 H...
British Journal of Pharmacology, 1998
1 Tolerance and dependence induced by chronic D-9-tetrahydrocannabinol (THC) administration were investigated in mice. The eects on body weight, analgesia and hypothermia were measured during 6 days of treatment (10 or 20 mg kg 71 THC twice daily). A rapid tolerance to the acute eects was observed from the second THC administration. 2 The selective CB-1 receptor antagonist SR 141716A (10 mg kg 71 ) was administered at the end of the treatment, and somatic and vegetative manifestations of abstinence were evaluated. SR 141716A administration precipitated several somatic signs that included wet dog shakes, frontpaw tremor, ataxia, hunched posture, tremor, ptosis, piloerection, decreased locomotor activity and mastication, which can be interpreted as being part of a withdrawal syndrome. 3 Brains were removed immediately after the behavioural measures and assayed for adenylyl cyclase activity. An increase in basal, forskolin and calcium/calmodulin stimulated adenylyl cyclase activities was speci®cally observed in the cerebellum of these mice. 4 The motivational eects of THC administration and withdrawal were evaluated by using the place conditioning paradigm. No conditioned change in preference to withdrawal associated environment was observed. In contrast, a conditioned place aversion was produced by the repeated pairing of THC (20 mg kg 71 ), without observing place preference at any of the doses used. 5 This study constitutes a clear behavioural and biochemical model of physical THC withdrawal with no motivational aversive consequences. This model permits an easy quanti®cation of THC abstinence in mice and can be useful for the elucidation of the molecular mechanisms involved in cannabinoid dependence.
Behavioural Brain Research, 2010
A single administration of an extremely low dose (0.002 mg/kg) of 9-tetrahydrocannabinol (THC; the psychoactive ingredient of marijuana) to ICR mice induced long-term cognitive deficits that lasted for at least 5 months. The behavioral deficits were detected by several tests that evaluated different aspects of memory and learning, including spatial navigation and spatial and non-spatial recognition. Our findings point to possible deficits in attention or motivation that represent a common upstream cognitive process that may affect the performance of the mice in the different behavioral assays. Similar ultra-low doses of THC (3-4 orders of magnitude lower than doses that are known to evoke the acute effects of THC) also induced sustained activation of extracellular-regulated kinase (ERK1/2) in the cerebellum, indicating that a single injection of such low doses of the cannabinoid drug can stimulate neuronal regulatory mechanisms. The relevance of these findings to the behavioral consequences of chronic exposure to marijuana is discussed.