Neuropeptide Y (NPY) mRNA in rat brain tissue: effects of decapitation andhigh-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 neuropeptide s and proteins, and it has been suggested that this may be valid also for n europeptide mRNAs. We therefore compared post-mortem NPY mRNA recovery foll owing decapitation or microwave irradiation. Total RNA yield was significan tly 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 mes sage levels were higher in occipital cortex, lower in the hypothalamus, and unaltered in the other brain regions examined. These results show that pos t-mortem processes contribute to estimates of NPY mRNA levels obtained usin g standard methods for obtaining brain tissue from experimental animals and raise the question whether different pools of NPY mRNA might be differenti ally affected by post-mortem degradation. A general protective effect of hi gh-energy radiation against degradation is not supported. (C) 2001 Harcourt Publishers LTD.