title: Serotonin's role in piglet mortality and thriftiness.
abstract: Improving piglet survivability rates is of high priority for swine production as well as for piglet well-being. Dysfunction in the serotonin (5-HT) system has been associated with growth deficiencies, infant mortalities, or failure to thrive in human infants. The aim of this research was to determine if a relationship exists between infant mortality and failure to thrive (or unthriftiness), and umbilical 5-HT concentration in piglets. Umbilical blood was collected from a total of 60 piglets from 15 litters for analysis of 5-HT and tryptophan (Trp; the AA precursor to 5-HT) concentrations. Behavior was scan sampled for the first 2 days after birth. Brain samples were also taken at 8 h after birth from healthy and unthrifty piglets (n = 4/group). The raphe nucleus was dissected out and analyzed for 5-HT and dopamine concentrations as well as their major metabolites 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), respectively. Data were analyzed by ANOVA. Piglets that died within 48 h of birth (n = 14) had significantly lower umbilical blood 5-HT concentrations at the time of their birth compared to their healthy counterparts (n = 46, P = 0.003). However, no difference in Trp was detected (P 0.38). Time spent under the heat lamp and sleeping were positively correlated with umbilical 5-HT levels (P = 0.004 and P = 0.02, respectively), while inactivity had a negative correlation with 5-HT levels (P = 0.04). In the raphe nucleus, the center for brain 5-HT biosynthesis, unthrifty piglets had a greater concentration of 5-HIAA (P = 0.02) and a trend for higher concentrations of 5-HT (P = 0.07) compared with healthy piglets. Dopamine levels did not differ between thrifty and unthrifty piglets (P = 0.45); however, its metabolite HVA tended to be greater in unthrifty piglets (P = 0.05). Our results show evidence of serotonergic dysfunction, at both the central and peripheral levels, accompanying early piglet mortalities. These data suggest a possible route for intervention, via the 5-HT system, to improve piglet survivability. However, further research is required to validate this hypothesis.
authors.affiliation: USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907 rldennis@umd.edu.
authors.forename: R L
authors.initials: RL
authors.lastname: Dennis
authors.affiliation: USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907.
authors.forename: K A
authors.initials: KA
authors.lastname: McMunn
authors.affiliation: USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907.
authors.forename: H W
authors.initials: HW
authors.lastname: Cheng
authors.affiliation: USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907.
authors.forename: J N
authors.initials: JN
authors.lastname: Marchant-Forde
authors.affiliation: USDA-Agricultural Research Service, Livestock Behavior Research Unit, West Lafayette, IN 47907.
authors.forename: D C
authors.initials: DC
authors.lastname: Lay
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006719:Homovanillic Acid / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008017:Life Expectancy; D008297:Male; D009026:Mortality; D012701:Serotonin / Q000097:blood* / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D014364:Tryptophan / Q000378:metabolism
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D004298:Dopamine; D006719:Homovanillic Acid
keywords: behavior; mortality; neonatal; pig; piglet; serotonin; tryptophan