A therapeutic dose decreases noradrenaline enough to cause side effects like constipation.

治疗剂量片类药物会导致肾上腺素水平减少，从而引发一些副作用，比如便秘。

The body compensates by increasing its number of noradrenaline receptors so it can detect much smaller amounts of noradrenaline.

为了对抗这种变化，人体会增加肾上腺素受体数量，以便能侦测到更低浓度 肾上腺素。

At the same time, opioids suppress the release of noradrenaline, which influences wakefulness, breathing, digestion, and blood pressure.

与此，片类药物 会抑制肾上腺素分泌，从而影响清醒度、呼吸、消化和血压。

Some research has found that there is a loss of noradrenaline neurons in the brain in Parkinson's patients.

有研究发现，帕金森患者脑内缺少“肾上腺素神经元”。

And so caffeine prevents this from happening, while also causing the body to increase production of dopamine and noradrenaline.

所以咖啡因可以阻止这种情况发生，也会导致身体产生更多多巴胺或肾上腺素。

That means there's a period of time when the body is too sensitive to noradrenaline.

这意味着，人体会有一段间对肾上腺素过于敏感。

But the body takes much longer to get rid of all the extra noradrenaline receptors it made.

但是人体需要更长间才能除掉体内生成额外肾上腺素受体。

The sympathetic neurons releases norepinephrine, also called noradrenaline, and the cells of the adrenal medulla release norepinephrine and epinephrine, also called adrenaline.

交感神经元释放肾上腺素，而肾上腺髓质细胞释放肾上腺素与肾上腺素。

As people take more opioids to compensate for tolerance, noradrenaline levels become lower and lower, to a point that could impact basic bodily functions.

随着人们摄取更多片类药物以补偿耐药性作用，肾上腺素水平就会逐渐降低，直到开始影响人体基本功能。

This increased sensitivity to noradrenaline allows the body to continue functioning normally— in fact, it becomes dependent on opioids to maintain the new balance.

这种对肾上腺素敏感度增加，让人体得以继续正常运作；事实上，人体变得必须依赖片类药物才能维持这种新平衡。