Separate administration of ammonium pyrrolidinedithiocarbamate and phorbol myristate acetate at early and late stages decreases secondary brain injury following intracerebral haemorrhage in rats via the NF-κB pathway

Introduction
Nuclear factor-kB (NF-kB) is a critical regulator of inflammatory responses following intracerebral haemorrhage (ICH). According to our previous study, inhibiting the p65 subunit at an early stage after ICH can reduce cell death, while inhibiting c-Rel at a late stage can lead to the opposite result. The aim of this study is to clarify whether patient prognosis can be improved by inhibiting p65 at the early stage and promoting c-Rel at the late stage.

Material and methods
Rats were divided into a sham group, ICH group, early NF-kB-inhibiting group using ammonium pyrrolidinedithiocarbamate (PDTC; group A, p65 subunit was dominant and inhibited at the early stage), late NF-kB-activating group using phorbol myristate acetate (PMA; group B, c-Rel was dominant and promoted at the late stage), and early NF-kB-inhibiting and late-activating group (group C, p65 subunit was inhibited at the early stage and c-Rel was promoted at the late stage). At preset time points after ICH, perihematomal tissue was obtained for detection of NF-kB activation, cell death, and expression of caspase-3, Bcl-2, and NF-kB subunits, to evaluate of the effect of PDTC and PMA.

Results
At four days after ICH, p65 expression (p < 0.01) and the number of TUNEL-positive cells (p < 0.01) in group A were significantly lower than in the ICH group. At 10 days after ICH, c-Rel expression in groups B and C was significantly higher than in other groups (p < 0.01 for all). TUNEL-positive cell numbers in groups A and B were significantly lower than in the ICH group, though more numerous than in group C (p < 0.01 for all).

Conclusions
Administration of both PDTC at the early stage and PMA at the late stage reduced perihematomal cell death after ICH, and using the two reagents together had a stronger anti-apoptotic effect than separate usage.