Psychological or physical prenatal stress differentially affects cognition behaviors

Introduction: Prenatal stress is proposed as a major risk factor in the development of cognitive impairments in the offspring. The objective of the current study was to evaluate the effect of prenatal physical or psychological stress on the motor and cognitive functions of male and female offspring. Methods: Adult female rats were stressed during their conception using a novel method to induced whether physical or psychological stress. Animal offspring were then kept until adulthood. Elevated plus maze (EPM) was used to evaluate their anxiety-like behavior. Rotarod and wire grip were used to evaluate muscle strength and balance function. Morris water maze (MWM) and passive avoidance (PA) learning and memory paradigm were used to evaluate the cognitive function of the offspring. Results: Female offspring of both physical and psychological stress had an increased anxiety-like behavior in the EPM test in comparison to female control rats. Balance function was impaired in physical stressed female offspring in comparison to the control and male offspring. Muscle strength was reduced in physical male and female offspring. Both male and female offspring groups that underwent prenatal physical and psychological stress had an impaired spatial learning and memory. PA learning and memory were impaired in both male and female offspring except for the psychological stress female offspring in PA learning. Conclusion: Results of our study revealed that prenatal physical or psychological stress have different effects on motor and cognitive functions of the offspring. Male and female offspring were differentially affected by prenatal stress. We suggest more studies to evaluate the role of sex hormones on the effects of prenatal physical or psychological stress on cognitive and motor functions of the offsprin

A Prospective Clinical Study on Blood Mercury Levels Following Endodontic Root-end Surgery with Amalgam

Introduction: The purpose of this clinical study was to compare the blood mercury levels before and after endodontic surgery using amalgam as a root-end filling material. Materials and Methods: Fourteen patients requiring periradicular surgery participated in this prospective clinical study. A zinc-free amalgam was employed as root-end filling material. Blood samples were collected at three intervals: immediately before, immediately after and one week postoperatively. Mercury content of the blood was determined using gold amalgamation cold-vapor atomic absorption spectrometry. Obtained data were analyzed using analysis of variance for repeated measures and paired t-test. Results: The mean (SD) of blood mercury levels was 2.20 (0.24) ng/mL immediately before surgery, 2.24 (0.28) ng/mL immediately after surgery and 2.44 (0.17) ng/mL one week after the periradicular surgery. The blood mercury level one week post-operative was significantly higher than both blood mercury levels immediately before (P<0.001) and immediately after (P=0.005) the surgery. Conclusion: Placement of an amalgam retroseal during endodontic surgery can increase blood mercury levels after one week. The mercury levels however, are still lower than the toxic mercury levels. We suggest using more suitable and biocompatible root-end filling materials

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

Psychological stress has a higher rate of developing addictive behaviors compared to physical stress in rat offspring

Prenatal stress could have great influence on development of offspring and might alter cognitive function and other physiological processes of children. The current study was conducted to study the effect of physical or psychological prenatal stress on addictive and anxiety-like behavior of male and female offspring during their adolescence period (postnatal day (PND) 40). Adult female rats were exposed to physical (swimming) or psychological (observing another female rat swimming) stress from day six of gestation for 10 days. Male and female offspring were assayed for anxiety-like behavior, motor and balance function and morphine conditioned place preference using the open field, elevated plus maze (EPM), rotarod and wire grip assay and conditioned place preference. Offspring in both physical and psychological prenatal stress groups demonstrated significant increase in anxiety-like behavior in EPM paradigm, but no alterations were observed in motor and balance function of animals. Offspring in the psychological prenatal stress group had an increased preference for morphine in comparison to control and physical prenatal stress groups. Results of the current study demonstrated that animals exposed to psychological stress during fetal development are at a higher risk of developing addictive behaviors. Further research might elucidate the exact mechanisms involved to provide better preventive and therapeutic interventions

Gender difference in motor impairments induced by chronic administration of vinblastine

Objective(s): Neurotoxicity of anticancer drugs complicates treatment of cancer patients. Vinblastine (VBL) is reported to induce motor and cognitive impairments in patients receiving chronic low-dose regimen. Materials and Methods: The effects of VBL treatment on motor, learning and memory functions of male and female Wistar rats were studied by behavioral related tests. Animals were given chronic intraperitoneal injections of VBL (0.2 mg/kg/week for 5 weeks) from postnatal day 23 to 52. Motor function was evaluated using grasping test and balancing was evaluated by the rotarod. Spatial learning and memory and anxiety-like behavior were determined using Morris water maze (MWM) task and open field test, respectively. Results: Administration of VBL caused severe damage to motor and balance function of male rats in comparison to female rats treated with VBL and rats treated with saline. Memory and locomotion were affected in both male and female rats compared with saline treated rats, while a sex difference was also observed in these parameters; male rats showed more impairment compared with female ones. Both male and female rats showed cognitive impairments in MWM task and no sex differences were observed in these functions. Conclusion: Results revealed that VBL is a potent neurotoxic agent and despite the profound effect of VBL on motor and cognitive functions, it seems that male rats are more susceptible to motor deficits induced by VBL

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

Termination of Nociceptive Bahaviour at the End of Phase 2 of Formalin Test is Attributable to Endogenous Inhibitory Mechanisms, but not by Opioid Receptors Activation

Introduction: Formalin injection induces nociceptive bahaviour in phase I and II, with a quiescent phase between them. While active inhibitory mechanisms are proposed to be responsible for initiation of interphase, the exact mechanisms which lead to termination of nociceptive response in phase II are not clear yet. Phase II is a consequence of peripheral and central sensitization processes, which can lead to termination of the noxious stimuli responses 45-60 minutes after formalin injection via possible recruitment of active inhibitory mechanisms which we have investigated in this study.  Methods: To test our hypothesis, in the first set of experiments, we evaluated nociceptive response after two consecutive injection of formalin (50&muL, 2%), with intervals of 5 or 60 minutes. In the next set, formalin tests were carried out in companion with injection of Naloxone Hydrochloride, a non-selective antagonist of opioid receptors, pre-formalin injection and 30 and 45 minutes post formalin injection.  Results: While normal nociceptive behaviour was observed in the group receiving one injection of formalin, a diminished response was observed in phases I and II of those receiving consequent injection of formalin, 60 minute after first injection. While second injection of formalin, 5 minute after first injection, had no effect. Administration of naloxone (1mg/kg) decreased nociception in phase 2A but had no effect on delayed termination of formalin test.  Discussion: The results of this study suggest the existence of an active inhibitory mechanism, other than the endogenous opioids, that is responsible for termination of nociceptive behaviour at the end of formalin test

Modulation of Different Phases of Formalin Test by Force Swim Stress

Introduction: The formalin test is the most accepted chemical test for evaluation of nociception. It requires the injection of an adequate amount of formalin into the surface of the hindpaw. Formalin test consists of phase 1 (0-7 min) and phase 2 (15-60) in which the animal shows painful behaviors. These phases are separated with a quiet phase named interphase, in which the nociceptive responses are decreased or completely disappeared. Methods: The goal of the current study was to evaluate the effects of swim stress at different heights of water on different phases of the formalin test in male rats. Results: Swim stress decreased nociceptive behaviors in first phase and prolonged interphase or delayed the start of second phase in a water height dependent manner. Swim stress in 25 and 50cm completely abolished the nociceptive behaviors in phase 1. Discussion: The present results showed different pain modulation during different phases of the formalin test and elucidated the impact of swim stress on duration of interphase. Interphase considered as an inactive period, but a recent research has shown that active inhibitory mechanisms are involved in the modulation of pain during this period. Therefore, swim stress may be considered as a useful tool for study of the basic inhibitory mechanisms underlying attenuation of nociceptive behaviors between phase 1 and 2 of the formalin test

Evaluation of Angiotensin-converting Enzyme 2 (ACE2) in COVID-19: A Systematic Review on All Types of Studies for Epidemiologic, Diagnostic, and Therapeutic Purposes: Angiotensin-converting enzyme 2 (ACE2) in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses the angiotensin-converting enzyme 2 (ACE2) receptor of SARS-CoV for cell entry. We aimed to check the association between ACE2 and COVID-19 (coronavirus disease 2019) in a systematic review. Two databases (PubMed/Medline and Scopus) and bioRxiv were checked for retrieving all types of studies in relation to ACE2 and COVID-19 until March 18, 2020. Forty-one studies were entered to the systematic review. These studies included nineteen original, eight reviews, four letters to the editor, three research papers, one correspondence, one commentary, one mini review, two reports, one opinion, and one perspective. In summary, the results showed that the ACE2 receptor for COVID-19 is similar to that of SARS-CoV. However, its expression was different in various populations as well as in the two genders. ACE2 may be used as a therapeutic target. Patients who take ACE inhibitors may have benefit in severe disease outcomes. Finally, pangolins and snakes and turtles may act as the potential intermediate hosts transmitting disease to humans