Early rhythm is entrained by the rhythm in breast feeding and care of the newborns. Apparently, before weaning, peripheral clocks’ setting by the feeding regime may prevail upon entrainment by the suprachiasmatic nuclei. Some potentially entraining substrates, like melatonin which derives from L-tryptophan, may be delivered in milk. From human studies, we also know that the circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn, and that infant formulas supplemented in Ltryptophan during the night can alter the expression of genes in cerebellum of nursing rat neonates. It has been found that acute supplementation with tryptophan show transitory increase of melatonin plasma levels as well as alteration in insulin secretion. Several interventions to reduce the long-term sequelae of early-life programming effects of several stressors have been used in animal models. The administration of folic acid with a low-protein diet during pregnancy prevents the altered phenotype and epigenotype in rat offspring, and administration of a diet rich in methyl donors prevents the transgenerational increase in obesity in agouti yellow mice. Some works underline that the timing of such interventions can be crucial. For instance, neonatal leptin treatment which reverses the programming effects of prenatal undernutrition can be reversed with leptin treatment between Day-3 and Day-13. Here we apply L-tryptophan supplementation from Day-12 of age because Coupe�� et al have identified extensive changes in gene expression of neurodevelopmental process related to cell differentiation and cytoskeleton organization, in the hypothalamus of rat pups born from low protein-fed mothers. As shown on adult rats, a daily bolus of L-tryptophan during 7 days enhances Vorinostat HDAC inhibitor serotonin levels over a 24 hour period, and produces an advance in the peak of serotonin in both plasma and different brain regions. Long-term influence of a daily bolus can be studied on the feeding pattern, growth curves as well as on plasma D-glucose which has been described to follow a circadian rhythm during the development of obesity in rats. Restricted feeding by providing a single meal at the same time each day is changing the daily profiles of PERIOD1 and PERIOD2 protein expression in brain nucleus of rats. To determine whether these alterations can be measured on somatic cells accessible by non-invasive means, we have chosen to establish primary cultures of rat tail. Somatic cells like fibroblasts can be synchronized by a serum shock to Vemurafenib re-induce clock gene expression and they are believed to harbor a complete set of clock genes, retaining a function similar to the one observed in the subject. Moreover, primary cultured cells are easily amenable to survival under amino acid-free conditions to follow the microtubule-associated-protein light chain 3b which is currently the only molecular marker available for following the autophagosome in cells. In this paper we have demonstrated a long-lasting effect of perinatal exposure to L-tryptophan on the blood D-glucose profile of male rats during the young and adult phases. On established primary cell lines, the expression of PERIOD1 protein after serum shock synchronization were different between L-tryptophan and undernourished saline groups with their controls.