| The aim of this study was to investigate the effect of early cysteamine (CS) exposure on CRH expression in hypothalamus of broiler chickens. Cysteamine was injected in ovo and the changes of CRH mRNA expression and number of CRH immunoreacticve neurons in hypothalamus was observed. Growing chickens were challenged with LPS in order to investigate whether early cysteamine exposure may program the response of hypothalamic CRH to LPS. Furthermore, cysteamine was fed to breeder hens in order to reveal the possible maternal effect of cysteamine in comparison with the effect of in ovo administration, and the mechanisms underlying such effect were discussed.1 Effect of in ovo CS administration on hypothalamic CRH in broiler chickensTwo hundred Ross broiler breeder eggs were divided randomly into two groups, the control group was injected in ovo with 100μL saline and the CS group with 700μg CS-HC1 (CS) in 100μl saline prior to incubation. At embryonic day 20 (E20), 10 embryos of each group were sampled and another 3 embryos from each group were perfused and the brains were sectioned for immunohistochemistry (IHC). After hatching birds of each group were weighted at day 1 (D1) and raised under the same feeding and housing condition till D20. In ovo CS administration did not affect the body weights (BW) or organ index (weights of liver, spleen and bursa fabricius relative to BW) at E20 or D1. However, mRNA abundances of CRH and SS in hypothalamus and CRH immunoreactive neurons in the PVN of hypothalamus were significantly decreased at E20 in CS group compared with control group. No significant difference of GR transcripts were observed at E20 or D1.From day (D) 16 to D20, chicks of each group were randomly allocated into basal and LPS-challenged subgroups, injected i.p. with saline or Lipopolysaccharide (LPS) at 500μg/kg BW every other day before sacrificed on D20. Although there was no significant difference of CRH mRNA in hypothalamus between the control and CS groups under basal condition, CS groups demonstrated higher response of CRH mRNA expression to LPS challenges, compared with control, which was consistent with their higher serum corticosterone level responding to LPS. Our results showed that in ovo CS administration may increase the sensitivity of HPA axis, probably through the early programming of hypothalamic CRH.2 Effect of maternal dietary CS supplementation on progeny hypothalamic CRH in broiler chickensFour hundred and eighty 67-week-old broiler breeder hens were allotted randomly to control and cysteamine-supplemented groups. Hens in cysteamine-treated group received a diet supplemented with a commercial cysteamine feed additive (containing 30% of cysteamine hydrochloride) at the level of 400 mg/Kg, while those in control group received the basal diet. Eggs were collected during the last 3 days in the 5th week after cysteamine treatment and incubated. Hypothalami were sampled at embryo 16, 20 (E16, E20) and day 1 of posthatch (D1). In addition, 3 brains from each group were perfused and sectioned at E20 and D1 respectively for IHC. Maternal CS had no significant effects on CRH mRNA expression in hypothalamus at E16, E20 or D1. No alterations were observed for SS mRNA in hypothalamus at E20 or the number of CRH immunoreactive neurons in the PVN at E20 or D1. These results suggest that maternal CS do not significantly affect progeny hypothalamic CRH mRNA expression or the number of CRH immunoreactive neurons in the PVN of hypothalamus.In conclusion, in ovo CS treatment decresed hypothalamic CRH and SS mRNA expression at E20, and increased the sensitivity of HPA axis in response to LPS challenge at D20. However, maternal CS administration did not show significant effects on progeny hypothalamic CRH mRNA expression or the number of CRH immunoreactive neurons.
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