Complex sentence: Under states of depression neurokinin immunoreactivity is increased in the frontal cortex, and decreased in the striatum, these peptide levels were not found to be treatable by lithium treatment in mice.
Split into simpler sentences: Under states of depression, neurokinin immunoreactivity is increased in the frontal cortex, and decreased in the striatum. These peptide levels were not found to be normalized by lithium treatment in mice.