Alright the next dopamine-directed class of therapies are inhibitors of COMT, catecholamine-O-methyltransferase, which is an enzyme that degrades dopamine and levodopa.

下一个针对胺的治疗药物是COMT抑制剂；COMT，即儿茶酚胺-O-甲基转移酶，是一种可以降解胺和旋的酶。

First, with the help of enzyme tyrosine hydroxylase (TH), tyrosine gets converted to L-dopa, also known as levodopa.

首先，在酪氨酸羟酶（TH）的帮助下，酪氨酸也转旋被称旋。

This is exactly why levodopa is administered with carbidopa, a dopa decarboxylase inhibitor that isn't able to cross the blood-brain barrier.

这也就是旋要和卡共用的原因；卡是一种不能通过血脑屏障的脱羧酶抑制剂。

Dopamine itself can't cross the blood-brain barrier, but its precursor levodopa can, and once in the brain, levodopa is converted to dopamine by dopa decarboxylase, most importantly within the remaining nigrostriatal neurons.

胺本身不能通过血脑屏障，但它的前体旋可以，一旦进入脑中，旋就会被脱羧酶转换胺，尤其是在残存的黑质纹状体神元内。

Motor symptoms respond to drugs used to treat Parkinson's disease, like levodopa, a dopamine analogue, while cognitive symptoms may improve with drugs for Alzheimer's disease, like donepezil, which increases acetylcholine availability.

针对运动障碍，可使用与帕金森病类似的药物，如胺类似物旋，而使用类似阿尔茨海默病的药物，可以改善认知症状，如奈哌齐，它能增加乙酰胆碱的供给。

COMT inhibitors like entacapone and tolcapone are only given with levodopa to prevent the enzyme from breaking it down outside the central nervous system, thus allowing more of it to enter the brain.

COMT抑制剂，例如恩他卡朋和托卡朋与旋一起用于治疗，只是了防止旋在中枢神系统外被分解，从而使更旋进入脑中。

Peripheral dopa decarboxylase also exists, which can metabolize levodopa into dopamine before it gets through the blood brain barrier, and—via additional enzymes— metabolize it into other catecholamines like epinephrine, which can cause unwanted side effects like arrhythmias.

体内还有外周脱羧酶，可以在旋穿过血脑屏障前将其转换胺；然后，通过其他酶将其转换其他儿茶酚胺，如肾上腺素，它可以导致不良的副作用，如心律失常。