Ovarian hormones prevent methamphetamine-induced anxiety-related behaviors and neuronal damage in ovariectomized rats

Methamphetamine (METH) may cause long-lasting neurotoxic effects and cognitive impairment. On the other hand, the ovarian hormones estrogen and progesterone have neuroprotective effects. In the current study, we aimed to examine the effects of estrogen and progesterone on anxiety-like behavior and neuronal damage in METH-exposed ovariectomized (OVX) rats. Three weeks after ovariectomy, the animals received estrogen (1 mg/kg, i.p.), or progesterone (8 mg/kg, i.p.), or estrogen plus progesterone (with the same doses), or vehicle during 7 consecutive days (days 22-28). On day 28, OVX rats were exposed to a single-day METH regimen (6 mg/kg, four s.c. Injections, with 2 h interval) 30 min after the hormone treatment. The next day (on day 29), the animals were assessed for anxiety-related behaviors using the open field and elevated plus-maze tasks. The animals were then sacrificed and brain water content, cell apoptosis and expression of IL-1 beta were evaluated. The findings showed that treatment with estrogen or progesterone alone in METH-exposed rats significantly improved hyperthermia, anxiety-like behavior, neuronal damage, and inflammation in the CA1 area. Also, treatment with estrogen plus progesterone improved hyperthermia and brain edema. Taken together, the findings suggest that treatment with ovarian hormones can partially prevent hyperthermia and anxiety-related behaviors induced by METH in OVX rats, which could be accompanied by their neuroprotective effects in the hippocampus.