Has anyone done immunocytochemistry for parvalbumin reactivity? I am trying to stain the GABA neurons of the medial septal region. The protocol I am using is only staining the cortex for some reason. However the samples I am using have been frozen in cryoprotectant and I am wondering if anyone knows anything about how quickly the parvalbumin protein degrades. Perhaps it degrades faster in the medial septum and fresh tissue would work better. I welcome any and all suggestions. Thank you.