Effects of treatment with estrogen and progesterone on the methamphetamine-induced cognitive impairment in ovariectomized rats.

Methamphetamine (METH) is one of the most powerful psychostimulant that leads to long lasting cognitive impairment. Earlier researches demonstrated that ovarian hormones including estrogen and progesterone ameliorate cognitive function against various central nervous system disorders. Moreover, recent studies demonstrate a neuroprotective role against methamphetamine toxicity. In current study the effects of estrogen and progesterone alone or in combination, on spatial learning and memory in METH-exposed ovariectomized (OVX) rats are investigated. Three weeks after ovariectomy, the animals were treated by estrogen (1mg/kg, i.p.) and progesterone (8mg/kg, i.p.) alone and in combination or vehicle during 14 consecutive days. On the 28th day, rats were exposed to a single-day METH regimens (four injections of 6mg/kg, s.c, at 2h intervals) 30min after the hormones treatment. Finally, spatial learning and memory were examined using the Morris water maze 2days after the last treatment. The findings showed that estrogen and progesterone did not have significant effect on spatial learning and memory in non METH-exposed OVX rats. The treatment with estrogen and progesterone alone in METH-exposed rats, significantly improved spatial learning and memory impairment. On the other hand, the cognitive performance of animals that received combination of estrogen plus progesterone in METH-exposed rats did not significantly differ from that of METH-exposed animals that received vehicle injections. Taken together, the present findings suggest that treatment with ovarian hormones can partially improve spatial learning and memory deficits induced by methamphetamine in OVX rats.