Serotonin (5-HT) receptor 5A sequence variants affect human plasma triglyceride levels.

Neurotransmitters such as serotonin (5-hydroxytryptamine, 5-HT) work closely with leptin and insulin to fine-tune the metabolic and neuroendocrine responses to dietary intake. Losing the sensitivity to excess food intake can lead to obesity, diabetes, and a multitude of behavioral disorders. It is largely unclear how different serotonin receptor subtypes respond to and integrate metabolic signals and which genetic variations in these receptor genes lead to individual differences in susceptibility to metabolic disorders. In an obese cohort of families of Northern European descent (n = 2,209), the serotonin type 5A receptor gene, HTR5A, was identified as a prominent factor affecting plasma levels of triglycerides (TG), supported by our data from both genome-wide linkage and targeted association analyses using 28 publicly available and 12 newly discovered single nucleotide polymorphisms (SNPs), of which 3 were strongly associated with plasma TG levels (P < 0.00125). Bayesian quantitative trait nucleotide (BQTN) analysis identified a putative causal promoter SNP (rs3734967) with substantial posterior probability (P = 0.59). Functional analysis of rs3734967 by electrophoretic mobility shift assay (EMSA) showed distinct binding patterns of the two alleles of this SNP with nuclear proteins from glioma cell lines. In conclusion, sequence variants in HTR5A are strongly associated with high plasma levels of TG in a Northern European population, suggesting a novel role of the serotonin receptor system in humans. This suggests a potential brain-specific regulation of plasma TG levels, possibly by alteration of the expression of HTR5A.

Digestibility and nutrient retention of perennial peanut and bermudagrass hays for mature horses.

Mature horses were used to determine apparent DM, OM, NDF, and CP digestibility values of 2 bermudagrass (BG; Cynodon dactylon) hays, Coastal (CB) and Tifton 85 (T85), and Florigraze perennial peanut (PP; Arachis glabrata) hay. In addition, N, Ca, and P balances were determined in horses fed those hays. Five mature Thoroughbred geldings and 1 Quarter Horse gelding (mean initial BW = 542 +/- 37 kg) were used (5 horses for the last period) in a 3 x 3 repeated Latin square design, with 2 horses per hay and 3 adjustment and collection periods. Horses were randomly assigned to pairs and the initial hay to be fed. Each period consisted of a 10-d adjustment phase, followed by a 4-d total fecal and urine collection phase. Horses were fed at 1.5 (period 1), 1.7 (period 2), or 2% (period 3) of their BW daily (DM basis). The 2 BG were grown under similar conditions, with CB and T85 being cut at 4 and 5 wk of regrowth, respectively, and PP being of a late first cutting. The compositions (DM basis) of PP, CB, and T85, respectively, were 93, 94, and 93% DM; 92, 94, and 94% OM; 46, 73, and 77% NDF; 34, 37, and 42% ADF; 11, 10, and 8% CP; 1.10, 0.28, 0.27% Ca; and 0.19, 0.15, and 0.19% P, respectively. Least squares means (pooled SE) for apparent digestibility of PP, CB, and T85, respectively, were 65, 53, and 52% (1) DM digestibility; 67, 53, and 52% (1) OM digestibility; 44, 50, and 46% (4) NDF digestibility; and 66, 60, and 57% (1) CP digestibility. Digestibility values of DM and OM were greater (P < 0.001) for PP than for the BG. Digestibility of CP was greater (P = 0.001) for PP than for CB or T85, with no difference (P = 0.37) between PP and BG hays in NDF digestibility. There were no differences between CB and T85 for DM digestibility (P = 0.67), OM digestibility (P = 0.59), CP digestibility (P = 0.11), and NDF digestibility (P = 0.48). Nitrogen (P = 0.01) and P balances (P = 0.04) were greater for PP than BG hays, whereas N balance of CB was greater (P = 0.01) than that of T85. There were no differences among all hays in Ca balance (P = 0.54) and between the BG in P balance (P = 0.34). Results indicated that PP, CB, and T85 are suitable forages for horses.