Bovine brain region-specific stearoyl-CoA desaturase expression and fatty acid composition

In this study, we sought to determine the relationship between stearoyl-CoA desaturase (SCD) gene isoform expression in the bovine brain and the accumulation of 18:1n-9. Two SCD gene isoforms are found in cows-SCD1 and SCD5. Samples of six brain regions (cerebellum, frontal cortex, hippocampus, hypothalamus, midbrain, and pons) were collected from animals at four different ages (neonates, weanlings, yearlings, and adults) for mRNA isolation and fatty acid analysis. Expression of SCD1 and SCD5 mRNA was compared across age groups to determine its developmental regulation. Fatty acid composition and SCD isoform mRNA expression were compared to examine the correlation of SCD1 and SCD5 with 18:1n-9 content in different brain regions. We found statistically significant correlations between SCD1 and SCD5 mRNA expression and the ratio of 18:1n-9 to 18:0 across age groups, with stronger correlations observed for SCD5. Similarly, there was a significant correlation between the ratio of 18:1n-9 to 18:0 and SCD5 mRNA expression across brain regions. SCD1 mRNA and the 18:1n-9 to 18:0 ratio were negatively correlated in the hippocampus. There was no trend of increasing 18:1n-9 content or SCD expression with age. Correlations indicated a stronger relationship between SCD5 mRNA expression and the 18:1n-9 to 18:0 ratio, potentially indicating a strong contribution of the SCD5 isoform to brain 18:1n-9 content. This is the first study examining a potential role for SCD5 in providing 18:1n-9 for brain lipids.