Role of the Androgen Receptors in Memory Impairment in Mature Male Rats

Steroidal sex hormones especially testosterone have a protective effect in neurodegenerative events such as Alzheimer Disease. The present study was designed to explore effect of testosterone and androgen receptors in memory impairment induced by intra- cerebroventricular (icv) injection of streptozotocin (STZ) as a model of sporadic AD. In this research animals were divided randomly into 11 equal groups. Experimental model of AD was induced by bilateral icv injection of STZ. STZ-induced memory impairment was assessed two weeks after the last dose of STZ by using a passive avoidance task. The interval between the placement of animals in the illuminated chamber and the entry into the dark chamber was measured as step-through latency (STL). Castration was performed by surgical removing of testis and behavioral study of memory impairment was done after 4 weeks. Results of this study showed that icv injection of STZ could induce marked (p<0.001) memory impairment. Memory was worsened in castrated rats (P<0.001) when compared with normal and sham-operated animals. Testosterone replacement therapy in 4 week castrated rats restored memory up to the level of control groups. Testosterone had not any significant effect on memory impairments of non-castrated rats. According to the obtained results it can be concluded that testosterone improves cognitive and memory impairment of AD.