Maternal separation impairs mother's cognition 1 month beyond the separation.

OBJECTIVE: Separation of pups from their dam during the infancy not only has detrimental effects on the pups' brain but also affects dams' behavior. Postpartum stress may affect mothers' cognitive functions. In the present study, by using a 180-min day-1 maternal separation (MS) paradigm, we assessed anxiety-like behavior and locomotor activity of rat dams which experienced separation from postnatal day (PND) 1 until weaning. We tried for the first time to clarify whether such separation impairs dam's performance in the Morris water maze. METHOD: We assessed dams' behavior at three time points: 24 h, 1 week, and 1 month after weaning. Therefore, the six groups consisted of control (CTRL) 24 h, 1 week, and 1 month and MS 24 h, 1 week, and 1 month, which was allocated in this study. RESULTS: Our results revealed that although MS-24 h and MS-1 week groups had intact locomotor activity, MS-1 month group showed less locomotor activity in the open field. Moreover, MS-induced anxiety-like behavior was more pronounced in MS-1 week and MS-1 month dams. Spatial learning and memory was also impaired only in MS-1 month dams. CONCLUSION: We can conclude that MS induces cognitive impairments in dam that may appear not immediately after the separation but a few weeks after such stressful event.

What are the consequences of Methylphenidate exposure for maternally separated rats?

Methylphenidate (MPH) abuse is prevalent among youth. Drug abuse results in pain perception. We sought to investigate whether Maternal separation (MS) prone to MPH addiction. The next question was whether MPH abusers with MS differ in pain perception. We investigated the impact of MS on addiction and drug reward as well as pain perception following 5 days of MPH injection in males and females rats. Initially, rats underwent MS protocol of 3 hr daily for 21 days. Conditioned place preference (CPP) test was an attempt to investigate whether MS rats experience more reward with MPH. The protocol consisted of 10 min habituation on Day 1, conditioning on Day 2-Day 6 (5 mg per kg MPH injection in drug compartment and saline in saline compartment with 4 hr gap between injections) and 10 min test on Day 7. Furthermore, using another group, differences in pain perception were investigated after 5 days of daily MPH injection with 5 mg per kg. Sensory pain sensitivity was tested on PND 39 using tail flick and hotplate in MS and control groups with and without MPH exposure. Results indicated that female rats are equally prone to addiction in CPP. On the other hand, MS males experience a higher reward in CPP. In tail flick test, female MS rats exposed to MPH show a lower sensory pain threshold with similar MPH exposure. Experiencing MPH similarly declined hotplate pain perception in MS and controls in the females. Males, on the other hand, did not show any difference in sensory pain tests. According to results one can argue MS is detrimental. MS males experience more reward with MPH, females are equally addiction prone and MS females experience more pain in tail flick. On the other hand pain threshold can decline in hotplate test for both control and MS females that received MPH.

Environmental enrichment and pain sensitivity; a study in maternally separated rats.

Rodents are highly dependent on maternal care after birth. Maternal separation (MS) is an animal model for studying neglect and abuse. Depriving the pup of such care renders the animal with Hypothalamic-Pituitary-adrenal (HPA) dysfunction and these animals are more susceptible to anxiety and stress as well as poor cognition. These effects are due to abnormal brain development in these animals. We have tried to investigate how maternal separation can affect pain sensation and whether a non-pharmacological intervention such as enriched environment (EE) can restore an abnormal pain sensation. Animals were put into four groups MS, control (CTRL) and MS + EE and CTRL + EE groups that underwent EE after weaning until adulthood. These groups were tested for pain sensitivity with hot plate and tail flick for sensory pain and formalin for affect pain. The results showed that MS rats are more sensitive to pain in the hot plate test and formalin test, however, no significant difference was seen between groups for tail flick test. When MS rats experience EE their pain sensitivity is restored at the behavioral level. Further research is required to see how EE restores pain sensation in MS rats.

The effects of high intensity exercise on learning and memory impairments followed by combination of sleep deprivation and demyelination induced by etidium bromide.

Introduction: Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. Cognitive impairments occurs in MS patients including learning and memory impairments. More than 50% of MS patients suffer from sleep problems. It has been suggested that in animal models exercise has direct neuroprotective effects on MS and sleep deprivation (SD). In this research, MS impairments were induced using a demyelination model as an indicator of MS disease. Also induction of SD was done using multiple platform. In order to focus on the research question, combination of MS model with SD was studied. In this study, the impact of treadmill exercise on learning and memory impairments was investigated. Material and methods: Male wistar rats were used in the present study. Exercise groups exercised daily for 1 h/day for 10 consecutive days with treadmill (speed: 18 m/min and inclination: 25°). The multiple platform method was applied for the induction of a 72 h SD. The cognitive functions were evaluated using Morris water maze (MWM) and open field tests. Animals were anaesthetized with a certain dose of ketamine and xylazin. After full anesthesia, the rat was placed on rat stereotaxic instrument in the skull-flat position. Demyelination was induced bilaterally by direct single injection of 3 µl of 0.01% ethidium bromide in sterile 0.9% saline at the rate of 1 µl/min into the hippocampal formation. The dose was injected using appropriate stereotaxic coordinates. Results: All of the learning and memory indices in the MWM task showed that SD and hippocampal demyelination destroy learning and memory. It seems that exercise can modulate the destructive effects of SD and demyelination on learning and memory at the behavioral level.