ALL steroids will cause testicular atrophy. As a steroid user, you should be well aware of this. Those cannot bother to take the time to educate themselves on the fundementals of AAS use have no business using steroids, while also forfieting the right to complian when they experience side effects.
All AAS cause suppression of the HPTA. Any time you take a steroid the body interprets it as androgen excess and immediately stops releasing the precursor hormones necessary for testosterone production. The same thing happens with fertility hormones--the ones repsonsible for initiating sperm production. This causes the testes to stop producing (or cut way back) on both testosterone and sperm production. Because the testes are no longer needed to fulfil its two primary functions, they begin to revert back to a prepubescent state, resulting in testicular atrophy.
Once the suppressive influence is removed (AAS) the body senses an androgen deficiency, which prompts the release of both testosterone and sperm precursor hormones. However, this process can often take months to complete. This is why we engage in PCT after a cycle of steroids--it helps restore production more quickly, which helps avoid gains loss and the mental-emotional side effects associated with testosterone deficiency.
The answer to your 2nd question lies within the first, as testosterones & DHT (DHT is a natural metabolite of testosterone) are necessary for normal sexual function-desire. So, when you use AAS, testosterone and DHT levels drop, causng a subsequent reduction in libido. How long it takes for libido to become probematic can vary depending on both the person, the type of stereoid(s) used, as well as the dosage. Normally, people don't exprience any type of major libido issues with short 4 week oral cycles, but if someone does, the only solution is to either go off or use testosterone/testosterone PH. IML sells 4-AD...a testosterone PH which will help maintain normal testosterone levels when on-cycle, thereby preventing testosterone deficiency and its resultant side effects.
