外源性孕酮对去势大鼠学习记忆的影响

Effects of Exogenous Progesterone on Learning and Memory of Ovariectomized Rats

目的研究外源性孕酮对去势大鼠的学习记忆能力的影响。方法 3月龄及5月龄健康雌性SD大鼠各60只。每年龄组随机为6组:正常组、卵切组、卵切+孕酮组、卵切+芝麻油组、假手术+孕酮组及假手术+芝麻油组。孕酮组皮下注射孕酮20mg/kg、芝麻油组皮下注射等体积的无菌芝麻油;以后每7天给药1次,共4次。给药3周后采用Morris水迷宫进行学习记忆能力检测。结果 3月龄青年大鼠卵巢切除去势后逃避潜伏期明显延长(P<0.01)、平台次数明显减少(P<0.01),外源性孕酮能使逃避学习成绩明显提高(P<0.01)、使记忆能力稍有改善(P<0.05);5月龄成年大鼠卵巢切除去势后逃避潜伏期延长(P<0.05)、平台次数明显减少(P<0.01),但外源性孕酮对逃避潜伏期及平台次数均无改善(P>0.05)。结论卵巢切除去势会引起青年和成年雌性大鼠的学习记忆能力下降;外源性孕酮能改善青年去势大鼠的学习记忆障碍,但不能提高成年去势大鼠的认知能力。

Objective To investigate the effects of exogenous progesterone on learning and memory in ovariectomized rats. Methods A total of 120 female Sprague- Dawley （SD） rats, three and five months old, were randomly divided into six groups： normal control （normal）, ovariectomized （OVX） , ovariectomized ＋ progesterone （ OVX ＋ P）, ovariectomized ＋ sesame oil （ OVX ＋ oil） , sham ＋ pro- gesterone （ sham ＋ P） , sham ＋ sesame oil （ sham ＋ oil） （ n = 10 for each group）. The rats in OVX ＋ P and sham ＋ P groups received sub- cutaneous injection of progesterone, 20mg/kg, and the rats in OVX ＋ oil and sham ＋ oil groups received injection of same volume of sesa- me oil, every 7 days for 4 administration. The learning and memory ability were tested on a Morris water maze 3 weeks later. Results The escape latency of 3 - month - old OVX was significantly longer than that of the control group （ P 〈 0.01 ）. The number for rats cross- ing platform was effectively decreased compared with the control （P 〈 0.01 ）. Injection of progesterone led to a significant improvement in learning （ P 〈 0.01 ） and memory ability of rats （P 〈 0.05 ） compared to OVX ＋ oil group. The escape latency of 5 - month - old OVX rats was significantly longer （ P 〈 0.05 ） ,and the number for rats crossing platform was significantly decreased（ P 〈 0.01 ） , as compared with the normal group, whereas exogenous progesterone injection did not result in any changes of the escape latency and the number for rats crossing platform in five - month - old OVX rats. Conclusion Ovariectomy operation led to an impairment of learning memory in 3 and 5 months old OVX rats. The exogenous progesterone attenuated impairments of learning and memory ability only in young OVX rats, but no significant improvement in the cognitive of adult OVX rats was observed.