A new microdissection technique for regional biochemical analysis of the rat spinal cord: serotonin, norepinephrine, dopamine and uric acid.
This report described a new microdissection procedure to evaluate the regional distribution of neuromediators in the rat spinal cord. Different segments are first divided into sagittal slices. From these, different grey and white matter regions can be microdissected. This permits selective biochemical measurements in different laminae, including the area around the central canal. White and grey matter can also be differentially analysed. Using HPLC with electrochemical detection, we report on the regional analysis of biogenic amines as well as uric acid. An increase in 5-hydroxytryptamine (5-HT) levels was observed from cervical to lumbar segments. 5-HT levels were highest in the motoneurone samples (lamina IX) of the lumbar cord. The next highest levels were found in lamina X, followed by the intermediate grey matter laminae and the dorsal horn. Small amounts of 5-HT were detected in the white matter. Interestingly, the ratio of 5-hydroxyindoleacetic acid (5-HIAA) to 5-HT was greatest in the white matter and least in the motoneurone sample. Norepinephrine (NE) levels were higher in the thoracic than in the cervical or the lumbar cord. The highest levels were found in the lamina X in thoracic segments. With this exception, no marked laminar difference in NE levels was observed. Dopamine (DA) levels were highest in the dorsal horn of the cervical and the thoracic cord, the next highest levels were found in the intermediate grey matter and lamina X in the same segments. The distribution of uric acid (UA) was comparable to that of NE: UA levels were highest in the thoracic cord, but no marked laminar difference was observed. On the other hand, UA levels in white matter generally exceeded those in the grey matter. These data indicate the value of a sagittal regional microdissection of the spinal cord. The ability to separately analyse different laminae of the cord (as well as differentiating grey and white matter) should prove useful in future studies of experimentally evoked changes in neurotransmitters within functionally distinct regions of the spinal cord.
D000818:Animals; D002395:Catecholamines / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004210:Dissection / Q000379:methods*; D004298:Dopamine / Q000032:analysis; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D008297:Male; D009638:Norepinephrine / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis*; D013116:Spinal Cord / Q000032:analysis / Q000601:surgery*; D014527:Uric Acid / Q000032:analysis*
D002395:Catecholamines; D014527:Uric Acid; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine; D009638:Norepinephrine