A new easy accessible and low-cost method for screening olfactory sensitivity in mice: behavioural and nociceptive response in male and female CD-1 mice upon exposure to millipede aversive odour

Statistical analysis of behavioral data

The statistical analysis of behavioral data follows the collection and checking of the data, and is aimed at assessing the effect of treatments on the observed behaviors. In this unit, different behavioral tests and the response variables collected in each test are briefly described, to introduce a detailed description of the strategies for the analysis of such data. The main purpose of this unit is to enable the reader to choose the appropriate procedure for the statistical analysis, based on the type of data and experimental design adopted. Moreover, conditions for the application of the most common parametric and nonparametric tests for the comparison among groups in regard to the measures of location are also presented. Finally, some suggestions on the presentation of results coming from the different statistical analyses are given.

Autoantibodies against opioid or glutamate receptors are associated with changes in morphine reward and physical dependence in mice

BACKGROUND

Possible interactions between nervous and immune systems during opioid addiction remain elusive. Recombinant mu-delta opioid receptors (MDOR) and the glutamate receptor 1 (GluR1) subunit of amino-3-hydroxy-5-methyl-4-isoxazole propionic acid glutamate receptors are involved in acute and chronic effects of morphine. Elevated levels of autoantibodies (aAbs) to these receptors were demonstrated in heroin human addicts and in animal models. This study characterized the role of aAbs to these receptors in behavioral modulations recruited during opioid tolerance and sensitization.

METHODS AND FINDINGS

Male CD-1 mice, immunized with either MDOR or GluR1 peptide fragments (80 microg intraperitoneal (i.p.)), were examined for spontaneous behavior and response to morphine (5 mg/kg i.p.). Spontaneous home-cage activity, novelty-induced self-grooming and morphine-induced hyperactivity were higher in GluR1 mice compared to Vehicle subjects, whereas MDOR immunization was associated with an increased morphine-induced conditioned place preference. In response to escalating doses of morphine (from 10 to 60 mg/kg i.p., twice daily) and naloxone-precipitated withdrawal (1 mg/kg subcutaneous), GluR1 mice exhibited a more marked stereotyped sniffing behavior and less body tremors compared to Vehicle subjects, whereas less sniffing and teeth chattering were found in MDOR mice. The expected downregulation of mu receptor binding sites, induced by chronic morphine in vehicle subjects, was completely absent following MDOR immunization.

CONCLUSIONS

These findings indicate an altered response to morphine-related reinforcing and aversive effects in MDOR mice and altered coping with the environment in GluR1 mice. Circulating aAbs to specific neuroreceptors may alter the response to opiates and play a role as determinants of vulnerability to opiate addiction.

Overview of behavioral teratology

The discipline of behavioral teratology is based on the study of behavior as a powerful tool to identify and disentangle noxious effects of compounds known or suspected to be potentially neurotoxic early during development. Indeed, because behavior is the ultimate output of the brain, behavioral assessments can provide critical information on the noxious actions exerted by selected chemicals-information which is different from, and complementary to, the information provided by neurochemical, cellular, and histological evaluations. In particular, behavioral assessments allow one to investigate the integrity of a number of brain processes, helping to identify selected structural and/or functional alterations. A large number of behavioral protocols are available which are rapid, simple, quantitative, easily replicable, and reliable as indices of brain dysfunction. This unit provides an overview of the field of behavioral teratology.