[Histonet] Helf- strange IF result

[sharon in]

 Hi,

I am detecting Arc (Activity regulated cytoskeletal protein) protein in rat
brain slices.
I perfuse transcardially the animal with 0.1M PBS and than 4% PFA with 5%
sucrose. Post fixation in 30% sucrose 1% PFA. In some cases when i take out
the brain after the perfusion i make small cut or incision with the skull in
the motor cortex, usually at the right side of the brain. I stain coronal
40um brain slices with primary antibody (from rabbit , santa cruz) and
secondary anti rabbit Alexa488. I found very strong nuclear staining in the
area around the cut in the motor cortex something like 100 um from each
side. Do somebody has any idea what is the source of that staining?
Generally the signal of Arc is in the nucleus and dendrites in other brain
regions. I have very consistent results with Arc expression in the brain
regions i am working on. The activation around the cutting area makes me
worry a little.
Thank you very much.