A tendency to depression may mean too little serotonin .

抑郁的倾向意味着血清素太少了。

Serotonin is one of the most important chemical messengers .

血清素是最重要的传递信息的化学物质之一。

Serotonin also regulates many cognitive processes , including mood .

血清素还调控包括情绪在内的许多认知过程。

The researchers don 't yet know whether serotonin affects sexual behavior in female mice .

研究人员还不知道血清素是否会影响雌性小鼠的性行为。

Among these chemicals , two of the most important are dopamine and serotonin .

在这些化学物质中，最重要的两种是多巴胺和血清素。