Neuropeptide Y (NPY) mRNA in rat brain tissue: effects of decapitation and high-energy microwave irradiation on post mortem stability.

mRNA recovery from brain tissue is affected by time-interval from death to inactivation of tissue, and may depend on sacrificial method. Sacrifice by high-energy microwave irradiation increases recovery of intact neuropeptides and proteins, and it has been suggested that this may be valid also for neuropeptide mRNAs. We therefore compared post-mortem NPY mRNA recovery following decapitation or microwave irradiation. Total RNA yield was significantly higher in tissue from decapitated rats. A decline in NPY mRNA (amol/mg tissue) over time, presumably reflecting degradation, was found in frontal cortex, hippocampus and striatum. Following high-energy microwaves, NPY message levels were higher in occipital cortex, lower in the hypothalamus, and unaltered in the other brain regions examined. These results show that post-mortem processes contribute to estimates of NPY mRNA levels obtained using standard methods for obtaining brain tissue from experimental animals and raise the question whether different pools of NPY mRNA might be differentially affected by post-mortem degradation. A general protective effect of high-energy radiation against degradation is not supported.