Tyrosine is needed to synthesize dopamine and norepinephrine, and tryptophan is needed to synthesize the neurotransmitter serotonin.

酪氨酸是合成多巴胺、去甲肾上腺素所必须的；色氨酸是合成神经递质血清素所必须的。

Serotonin is one of the oldest neurotransmitters.

“血清素是最古老的神经递质之一。”

Specifically, the genes that express your serotonin receptors.

更准确地说，是表达血清素受体的基因。

One of those relief-providing chemicals is serotonin, a neurotransmitter.

提供缓解的化学物质之一是血清素，一种神经递质。

Patients with schizophrenia often have elevated levels of serotonin in the brain.

患有精神分裂症的病人大脑通常拥有较高的血清素水平。

One widespread impression among the public is that depression is caused by having too little serotonin.

公众普遍认为抑郁症是由血清素过少而引起的。

Because MDMA affects serotonin, a nervous system chemical.

这是因为MDMA会影响一种名为“血清素”的神经系统化学物质。

And finally, higher levels of serotonin are associated with greater confidence.

最后，血清素水平越高，越能加强自信。

First, it optimizes the levels of neurotransmitters like serotonin, norepinephrine, and dopamine.

首先，它能优化神经递质水平，如血清素、去甲肾上腺素和多巴胺。

First off, serotonin isn't the only neurotransmitter that plays a role.

首先，5-羟色胺不是唯一起作用的神经递质。