Analysis of equine cisterna magna cerebrospinal fluid for the presence of some monoamine neurotransmitters and transmitter metabolites.
Small volumes (0.05 ml) of cisterna magna cerebrospinal fluid (CSF) from 23 neurologically normal horses were analysed for the monoamine neurotransmitters dopamine, norepinephrine, epinephrine, serotonin and their metabolites using high pressure liquid chromatography and electrochemical detection. Two metabolites, homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were present in all CSF samples. The deaminated and methylated metabolite of dopamine, HVA, was present at a mean concentration of 42.33 +/- 3.14 ng/ml of CSF. The deaminated metabolite of serotonin, 5-HIAA, was present at a mean concentration of 45.52 +/- 3.65 ng/ml of CSF. A positive correlation was found between the CSF concentrations of HVA and 5-HIAA (r = 0.72, p = 0.0003). The mean ratio of HVA to 5-HIAA concentrations was 1.07 +/- 0.05. The ratios of HVA to 5-HIAA concentrations were found to be more indicative of the serotonergic metabolite 5-HIAA (r = -0.62, p = 0.0016) than the dopaminergic metabolite HVA (r = 0.11, p = 0.60). There was a stronger relationship between the concentrations of 5-HIAA and the ratios of HVA to 5-HIAA in male CSF (r = -0.85, p = 0.0006) than in female CSF (r = -0.54, p = 0.01). Concentrations of CSF neurotransmitter metabolites were evaluated in horses grouped by age (0-4, 5-9 and 10-13 years). The youngest group of horses had a significantly (p = 0.003) greater CSF concentration of HVA than of 5-HIAA. The 10-13-year-old horses had a significantly (p = 0.02) lower mean CSF HVA concentration than the 0-4-year-old horses. No age-related differences in CSF 5-HIAA concentrations were detected.
Vaughn
D M
DM
Medicinal Biochemistry Laboratory, Scott-Ritchey Research Program, College of Veterinary Medicine, Auburn University, Alabama 36849-5525.
Smyth
G B
GB
Whitmer
W L
WL
Satjawatcharaphong
C
C
D015102:3,4-Dihydroxyphenylacetic Acid / Q000134:cerebrospinal fluid; D000375:Aging; D000818:Animals; D015306:Biogenic Monoamines / Q000134:cerebrospinal fluid*; D002946:Cisterna Magna / Q000032:analysis*; D005260:Female; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid; D006736:Horses / Q000134:cerebrospinal fluid*; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid; D008297:Male; D018377:Neurotransmitter Agents / Q000134:cerebrospinal fluid*
D015306:Biogenic Monoamines; D018377:Neurotransmitter Agents; D015102:3,4-Dihydroxyphenylacetic Acid; D006897:Hydroxyindoleacetic Acid; D006719:Homovanillic Acid