Role of Opioid System in Empathy-like Behaviours in Rats

Background: Empathy is defined as the ability to simulate the mental states of others. Recent studies havedemonstrated empathy-like behaviors in other animals including rats and mice. The objective of the currentstudy was to evaluate the effect of acute administration of morphine and naloxone on cognition andnociception changes following observing conspecifics undergoing nociceptive stimulus.Methods: Adult male Wistar rats were used (n = 8 for each group). One cagemate received formalin injectioninto the hindpaw five times within a nine-day period and the other cagemate observed the pain while beingpretreated with saline, morphine, or naloxone [10 mg/kg, intraperitoneal (i.p.)]. Pain behaviors, anxiety-likebehaviour, locomotion, balance and muscle strength were evaluated in the observer animals.Findings: Observing a cagemate in pain increased anxiety-like behavior and reduced thermal pain threshold in theobserver animals. Administration of morphine reversed these effects and naloxone did not affect the responses.Conclusion: Results of the current study reveal an important role for opioid receptors (ORs) in empathy forpain, so that activation of this system dampens the empathy-like responses

Chronic Exposure to Morphine Leads to a Reduced Affective Pain Response in the Presence of Hyperalgesia in an Animal Model of Empathy

Background: Empathy is the capability to represent the mental and emotional states of other subjects.Previous studies have demonstrated a possible correlation between morphine addiction and altered empathyresponse in morphine-addicted subjects. This study was performed to evaluate the effect of chronic morphineexposure as an animal model of morphine addiction on empathic changes in affective and sensory pain.Methods: Adult male Wistar rats (3 months old) were used for the current study. Animals were grouped incages of two (n = 8 for each group) and one animal was selected as the pain observer group. Pain observeranimals received either saline or morphine (10 mg/kg, twice daily for 8 days). At ninth day, formalin [50 µg,5%, subcutaneous (SC)] was injected into the hindpaw of the cagemate and placed inside the cage. Elevatedplus maze (EPM) and open field test (OFT) were recruited to evaluate anxiety; hot plate and tail flick testswere used to assay sensory pain. Conditioned place aversion (CPA) was also measured as indicator ofaffective pain component.Findings: Chronic morphine exposure led to a reduced level of anxiety in EPM and OFT assays. An opioidinduced hyperalgesia was observed in the sensory pain assays, while there was a reduced affective pain in theCPA paradigm in morphine-treated animals.Conclusion: It might be plausible that chronic morphine exposure might alter empathy for pain throughaffective and not sensory pain pathway

Dataset underlying the publication: Interleukin 7 receptor T244I polymorphism and the multiple sclerosis susceptibility: a meta-analysis

Multiple sclerosis (MS) is recognized as the most prevalent chronic inflammatory neurological disorder diagnosed in young adults. Recent evidence suggests that the T244I polymorphism of the IL7Rα gene (rs6897932) May influence MS susceptibility; however, individual studies have provided conflicting and controversial results. Therefore, this meta-analysis was conducted to assess the association between the IL7R T244I polymorphism and the risk of MS

Ecstasy-Induced Caspase Expression Alters Following Ginger Treatment

Introduction: Exposure to 3-4, methylenedioxymethamphetamine (MDMA) leads to cell death. Herein, we studied the protective effects of ginger on MDMA- induced apoptosis. Methods: 15 Sprague dawley male rats were administrated with 0, 10 mg/kg MDMA, or MDMA along with 100mg/kg ginger, IP for 7 days. Brains were removed to study the caspase 3, 8, and 9 expressions in the hippocampus by RT-PCR. Data was analyzed by SPSS 16 software using the one-way ANOVA test. Results: MDMA treatment resulted in a significant increase in caspase 3, 8, and 9 as compared to the sham group (p<0.001). Ginger administration however, appeared to significantly decrease the same (p<0.001). Discussion: Our findings suggest that ginger consumption may lead to the improvement of MDMA-induced neurotoxicity