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Animal study: continuous steroid use keeps testes young

Chemical athletes who have spent most of their lives taking steroids are in for a surprise when they finally come off the things at the end of their career: their testes may be producing just as much testosterone as they did when they were young. The steroids they take will have stopped their testes from ageing. We base this on an animal study published a decade ago in the Proceedings of the National Academy of Sciences.

Synthetic androgens trick your brain into thinking that the concentration of testosterone in your body is so high that the testes no longer need to function. The pituitary gland stops producing LH and FSH, which stimulate the Leydig cells in the testes to produce testosterone. The testicles shrink and production of sperm and hormones stops. Bad news, say doctors. If things go wrong, production will never start up again.

The doctors' caution is based on medical case studies in which ex-steroids users' hormonal balance never did recover. You can find examples in the literature of bodybuilders who, after a year of being clean, are still infertile. [Fertil Steril. 2003 Jun;79 Suppl 3:141-3.]Sometimes old fashioned medicine like clomid [Fertil Steril 2003 Jan;79(1):203-5.] or LHRH [Int J Sports Med 2003 Apr;24(3):195-196.] helps. And sometimes it doesn't.

Endocrinologists at Johns Hopkins University decided to examine the effect of exogenous androgens at a more fundamental level, so they set up an experiment with rats. Rats aged three months (young) and thirteen months (aged) were fitted with an implant that emitted testosterone - enough to suppress their own production. After eight months one third of a rat lab's life expectancy the researchers removed the implants. They waited a few months for the animals' endocrine system to recover, and then measured how much testosterone the animals were producing. They compared the testosterone levels with those of rats who had not been treated.

The bars on the left of the graph below show the testosterone level of the control rats. The older rats produced less testosterone than the young ones. That's normal. Why this is so is not known. We do know, however, that it's not got anything to do with the LH-level: older animals make just as much LH as younger ones do.

In the middle of the graph you see the rats' bodies own production in the period when they were given exogenous testosterone: nil nada.

The bars on the right show the production levels in the animals after the implants had been removed. As you can see, the older rats are producing as much testosterone as the younger animals.

Animal study: continuous steroid use keeps testes young

In the reactivated testes, all enzymes involved in the production of testosterone are working as though the testes are younger. The graphs below show the effect of exogenous administration on 17alpha-hydroxylase [the enzyme that converts pregnenolone into 17-alpha-hydroxy-pregnenolone], C17-20-lyase [the enzyme that converts 17-alpha-hydroxy-pregnenolone into DHEA] and 3-beta-HSD [the enzyme that DHEA converts into androstenedione].

Animal study: continuous steroid use keeps testes young

The researchers suspect that testes age because they are active. Perhaps the process of testosterone and sperm production leads to the release of free radicals that damage the tissue, they speculate. Whatever mechanism is at work, the testes of steroids users may well be comparable to every second-hand car dealer's dream: one careful lady owner: spent more time in the garage and has hardly ever been used.

Of course, humans are not rats. In studies of ex-steroids users who have been off steroids for over a year, researchers have sometimes recorded lower hormone levels. [J Steroid Biochem Mol Biol. 2003 Feb;84(2-3):369-75.]

Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):14877-81.