Perinatal growth restriction is not related to higher intestinal distribution and increased serum levels of 5-hydroxytryptamin in piglets.

Serotonin [5-hydroxytryptamin (5-HT)] is abundantly present in intestinal enteroendocrine cells and neurons and plays a crucial role in gastrointestinal functions (i.e., motility and mucosal secretion). Increased concentrations of 5-HT and its precursor l-Trp are present in plasma and brain tissues in case of intrauterine growth retardation (IUGR). Therefore, 5-HT might be involved in the impaired gastrointestinal function associated with IUGR. Small-for-gestational-age (SGA) piglets have been widely used as animal model for IUGR. Hence, the density of intestinal 5-HT cells in fetal and neonatal SGA piglets was compared with serotonergic cell density in normal weight (NW) littermates. Furthermore, 5-HT serum concentrations of the neonatal piglets were analyzed. Stereological analysis showed that fetal piglets have higher (P < 0.01) volume densities of 5-HT enteroendocrine cells compared to 3-d-old piglets irrespective of BW. Serum concentrations did not differ in relation to postnatal age (P = 0.637) and BW (P = 0.892). These results contrast with serum and brain 5-HT and l-Trp levels in human and guinea pig SGA individuals and seemingly contest the fact that 5-HT plays an important role in gut impairment in SGA.