Does any hormones or enzymes been secreted when a person feels a depression?!

Does any hormones or enzymes been secreted when a person feels a depression?

Hello,

I was wondering, if while a person is depressed (mentally) his body is secreting some kind of hormones or enzymes which make them (the depressed people bodies) feel weak.

Thank you.

There are hormones that are generally high in depression, such as ACTH, a sign of stress, but they don't make a person weak in that setting.

The lack of energy when one is depressed is not in the muscles. When I was depressed if I could get myself to exercise, I was fine at it. The problem is rather a lack of motivation, though not in any normal sense of the word "motivation". It felt like something in me was dead. If I didn't breathe automatically, I wouldn't have even bothered to do that.

Researchers can induce a more or less instant depression in susceptible subjects by giving them amino acids deficient in tryptophan, which lowers brain serotonin. If you search on "acute tryptophan depletion" you can find some papers about that. Whether that's the whole story behind feeling as depressed as I once did or whether there is other biology that goes into that remains to be seen, but people speculate about that.

Here's the abstract of a relevant article:

http://www.nature.com/mp/journal/v12/n6/...