Anabolic-androgenic steroid and adrenal steroid effects on hippocampal plasticity.
Anabolic-androgenic steroids (AAS) are synthetic androgen-like compounds which are taken in high doses by athletes with the intention of enhancing muscular appearance, strength and/or athletic performance. Recent research indicates that high doses of AAS may influence the functions of the hippocampus. This evidence led us to explore the extent to which chronic AAS treatments influence spatial memory and the integrity of the hippocampus in the rat. Gonadally intact adult male Long-Evans rats were treated with either the AAS methandrostenolone, a steroid 'cocktail' (TNB; testosterone cypionate, boldenone undecylenate and nandrolone decanoate), or the oil vehicle daily for 12 weeks. A group of male rats treated with corticosterone (CORT; 10 mg/day) was also examined. Spatial memory was assessed in the Morris water maze after 10 weeks of hormone treatment. At 12 weeks, the animals were sacrificed, blood collected and the brain sectioned to assess hippocampal cell number. There were no impairments in the acquisition or retention of the Morris water maze in any hormone treatment group. Although serum testosterone levels were elevated in rats treated with TNB relative to the oil controls, neither the TNB or methandrostenolone treatments produced changes in hippocampal cell number. Serum CORT levels were significantly elevated in the rats treated with CORT and cell loss (15%) was detectable in the CA3b subfield in this group of animals. These results indicate that the AAS administered in the present study were not detrimental to hippocampal spatial memory or cell survival and that, while chronic CORT may produce mild hippocampal cell loss, this loss is not accompanied by deficits on a spatial memory task.