Nandrolone decanoate enhances hypothalamic biogenic amines in rats

To identify possible mechanisms for an anabolic-androgenic steroid induced increase in aggressive behavior and work capacity, the levels of some biogenic amines considered to be closely related to a systemic hyper-adrenergic state were measured in selected regions of the brain.

Wistar male rats were divided randomly into five groups: nontreated (control), oil-vehicle-treated (vehicle) or one of three (therapeutic dose and 10- or 100-fold higher dose) anabolic-androgenic steroid-treated (steroid-1, -2, -3) groups. Rats in the steroid and vehicle groups were given a single dose of nandrolone decanoate or oil vehicle, respectively, one week before tissue sampling. The levels of norepinephrine (NE) and its metabolite, 4-hydroxy-3-methoxyphenylglycol (MHPG), serotonin (5-HT) and its metabolite, 5-hydroxy-indole-3-acetic acid (5-HIAA) were measured in the cerebral cortex, hypothalamus and cerebellum by high-performance liquid chromatography. Immunostaining for c-fos was performed as a confirmation of increased neural activity.

The levels of NE and MHPG were increased by approximately 2- and approximately 7-fold in the hypothalamus of the steroid-2 compared with the control and vehicle groups. The levels of 5-HT and 5-HIAA were approximately 40 and approximately 50% higher in the steroid-2 compared with the control and vehicle groups. A significantly higher number of c-fos expressing neurons were observed in the periventricular region of the steroid-2 than the control and vehicle groups, indicating enhanced neuronal activity after nandrolone decanoate treatment.

The present results, combined with previously reported findings of physical performance enhancement after anabolic-androgenic steroid treatment, are consistent with the interpretation that elevated levels of adrenergic and serotonergic amines in the hypothalamus could contribute to aggressive behaviors as well as improved physical performance.