Biting Suppresses Stress-induced Expression of Corticotropin-releasing Factor (CRF) in the Rat Hypothalamus

Corticotropin-releasing factor (CRF) expressed in the hypothalamus plays an important role in mediating behavioral responses to stressors. Restraining the body of an animal has been shown to activate and induce an enhanced expression of CRF in paraventricular neurons of the rat hypothalamus. Since aggressive biting behavior is known to suppress stress-induced noradrenaline secretion in the central nervous system and the formation of gastric ulcers, we investigated the effect of biting on restraint-induced CRF expression in the rat hypothalamus. The number of CRF-expressing neurons in the paraventricular nucleus increased significantly after short time restraint (30 or 60 min) followed by a 180-minute post-restraint period. Biting of a wooden stick during the restraint stress significantly suppressed the restraint-induced enhancement of CRF expression in the paraventricular nucleus. These observations suggest a possible anti-stress effect of biting and an important role of para-functional masticatory activity in coping with stressful events.

Evaluating remediation of radionuclide contaminated forest near Iwaki, Japan, using radiometric methods

Radiometric surveys have been conducted in support of a project investigating the potential of biofuel power generation coupled with remediation of forests contaminated with radionuclides following the Fukushima Daiichi accident. Surveys conducted in 2013 and 2014 were used to determine the distribution and time dependence of radionuclides in a cedar plantation and adjacent deciduous forestry subject to downslope radionuclide migration, and a test area where litter removal was conducted. The radiocaesium results confirmed enhanced deposition levels in the evergreen areas compared with adjacent areas of deciduous forestry, implying significant differences in depositional processes during the initial interception period in 2011. Surveys were conducted both with and without a collimator on both occasions, which modified the angular response of the detector to separate radiation signals from above and below the detector. The combined data have been used to define the influence of radionuclides in the forest canopy on dose rate at 1 m, indicating that, in evergreen areas, the activity retained within the canopy even by 2013 contributed less than 5% of ground level dose rate. The time dependent changes observed allow the effect of remediation by litter removal in reducing radionuclide inventories and dose rates to be appraised relative natural redistribution processes on adjacent control areas. A 15 × 45 m area of cedar forest was remediated in September 2013. The work involved five people in a total of 160 person hours. It incurred a total dose of 40-50 μSv, and generated 2.1 t of waste comprising forest litter and understory. Average dose rates were reduced from 0.31 μSv h^-1 to 0.22 μSv h^-1, with nuclide specific analyses indicating removal of 30 ± 3% of the local radiocaesium inventory. This compares with annual removal rates of 10-15% where radionuclide migration down-slope over ranges of 10-50 m could be observed within adjacent areas. Local increases were also observed in areas identified as sinks. The results confirm the utility of time-series, collimated, radiometric survey methods to account for the distribution and changes in radionuclide inventory within contaminated forests. The data on litter removal imply that significant activity transfer from canopy to soil had taken place, and provide benchmark results against which such remediation actions can be appraised.