Effect of haemorrhage on the expression of neurotransmitter-related genes in rat ventrolateral medulla: a...

The ventrolateral medulla (VLM) has three functionally defined regions that contain catecholamine-synthesising neurons (rostral C1, caudal C1 and A1 regions). Many neuromessengers can alter cardiovascular functions in the VLM. The aims of this study were, first to validate the utility of real-time RT-PCR SYBR Green assay for quantitation of mRNA expression levels of neuromessengers in small site-specific neuronal populations in the VLM, and second to compare the basal mRNA levels of the adrenaline-synthesizing enzyme phenylethanolamine-N-methyltransferase (PNMT), neuropeptide Y (NPY) and preproenkephalin (ENK) in the three regions and third to examine the effects of haemorrhage on the expression of these three genes. Rats were anaesthetised with sodium pentobarbital and divided into three groups: perfused, sham-operated and haemorrhaged. A 15% haemorrhage was carried out on the haemorrhaged group. It was found that there are regional differences in the level of mRNA expression for all the three genes: with, in general, decreases from the rostral to caudal regions of VLM. A 15% haemorrhage significantly induced expression of PNMT in the rostral C1 region and NPY in the caudal C1 and A1 regions but had no effect on ENK at any sites, suggesting a differential regulation on the expression of these three genes in the VLM. Our results also demonstrate that real-time RT-PCR is a sensitive and accurate method for quantitative studies on neurotransmitter gene expressions in restricted brain regions.