Analgesic effect of voluntary exercise in a rat model of persistent pain via suppression of microglial activation in the spinal cord.

In this study, we employed a rodent model for persistent allodynia and hyperalgesia to determine whether voluntary exercise could exert analgesic effects on these pain symptoms. Rats were subcutaneously injected with formalin into the plantar surface of the right hind paw to induce mechanical allodynia and hyperalgesia. We assessed the analgesic effects of a voluntary wheel running (VWR) using the von Frey test and investigated microglial proliferation in the dorsal horn of the spinal cord. We also determined the effect of formalin and VWR on the protein expression levels of brain-derived neurotrophic factor (BDNF), its receptor TrkB, and K+-Cl- cotransporter 2 (KCC2), which play a key role in inducing allodynia and hyperalgesia. Rats with access to the running wheels showed beneficial effects on persistent formalin-induced mechanical allodynia and hyperalgesia. The effects of VWR were elicited through the suppression of formalin-induced microglial proliferation, TrkB up-regulation, and KCC2 down-regulation in the spinal cord. BDNF, however, might not contribute to the beneficial effects of VWR. Our results show an analgesic effect of voluntary physical exercise in a rodent model with persistent pain, possibly through the regulation of microglial proliferation and TrkB and KCC2 expression in the spinal cord.

Development of a prediction model for child maltreatment recurrence in Japan: A historical cohort study using data from a Child Guidance Center.

To develop a prediction model for the first recurrence of child maltreatment within the first year after the initial report, we carried out a historical cohort study using administrative data from 716 incident cases of child maltreatment (physical abuse, psychological abuse, or neglect) not receiving support services, reported between April 1, 1996 through March 31, 2011 to Shiga Central Child Guidance Center, Japan. In total, 23 items related to characteristics of the child, the maltreatment, the offender, household, and other related factors were selected as predictive variables and analyzed by multivariate logistic regression model for association with first recurrence of maltreatment. According to the stepwise selection procedure six factors were identified that include 9-13year age of child (AOR=3.43/95%CI=1.52-7.72), <40year age of the offender (AOR=1.65/95%CI=1.09-2.51), offender's history of maltreatment during childhood (AOR=2.56/95%CI=1.31-4.99), household financial instability or poverty (AOR=1.64/95%CI=1.10-2.45), absence of someone in the community who could watch over the child (AOR=1.68/95%CI=1.16-2.44), and the organization as the referral source (AOR=2.21/95%CI=1.24-3.93). Using these six predictors, we generated a linear prediction model with a sensitivity and specificity of 45.2% and 82.4%, respectively. The model may be useful to assess the risk of further maltreatment and help the child and family welfare administrations to develop preventive strategies for recurrence.