Takahashi L K, Kim H
Department of Psychiatry, University of Wisconsin Medical School, Madison 53792-2475.
Neurosci Lett. 1994 Aug 1;176(2):272-6. doi: 10.1016/0304-3940(94)90099-x.
We tested the hypothesis that in preweanling rats central administration of exogenous corticosterone (CORT) is sufficient to facilitate the development of behavioral inhibition. 28-gauge cannulae containing varying concentrations of CORT (0, 25, 50 and 100%) were implanted unilaterally into the lateral ventricles of 9-day-old rat pups. After a 24-h postoperative recovery period, pups were adrenalectomized. At 14 days of age, pups were tested for behavioral inhibition which consisted of removing the pup from the nest and exposing it to an unfamiliar adult male rat. Pups implanted with cannulae containing 0, 25 and 50% concentrations of CORT spent significantly less time in freezing postures than pups implanted with cannulae containing 100% CORT. These freezing pups also tended to emit fewer ultrasonic vocalizations than pups in the other three implant conditions, albeit the level obtained was not statistically significant. RIAs indicated that, in general, hormone-filled cannulae produced no detectable concentrations of plasma CORT on the day of the test or on days preceding testing. Results suggest that in the early postnatal period endogenous CORT acts centrally to facilitate the development of neural pathways involved in the ontogenetic expression of behavioral inhibition.
在断奶前大鼠中，中枢给予外源性皮质酮（CORT）足以促进行为抑制的发展。将含有不同浓度CORT（0%、25%、50%和100%）的28号套管单侧植入9日龄幼鼠的侧脑室。术后恢复24小时后，对幼鼠进行肾上腺切除术。在14日龄时，对幼鼠进行行为抑制测试，即将幼鼠从巢中取出并使其接触一只陌生的成年雄性大鼠。植入含0%、25%和50%CORT套管的幼鼠在冻结姿势下花费的时间明显少于植入含100%CORT套管的幼鼠。与其他三种植入条件下的幼鼠相比，这些处于冻结状态的幼鼠发出的超声波叫声也往往较少，尽管所测得的水平无统计学意义。放射免疫分析表明，总体而言，在测试当天或测试前几天，充满激素的套管未产生可检测到的血浆CORT浓度。结果表明，在出生后早期，内源性CORT在中枢发挥作用，以促进参与行为抑制个体发育表达的神经通路的发展。
