replaced = substituted? overstressed = nervous?

replaced = substituted?

I think that 'put back' is closer than 'substituted'. The latter gives the feeling of a new substance being put in place while 'replaced' means that the same proteins are put back.

overstressed = nervous?

'nervous' could be one of the things that happen from the many more signaling substances being released. The flies are getting too many different directions, like if ten people were all telling you to do different things at the same time. How would you feel? Confused which would lead to stress. As this is constant, the flies would become overstressed.

Thank you.