ICV CRF and isolation stress differentially enhance plasma corticosterone concentrations in layer- and meat-type neonatal chicks.
The present study compared the plasma corticosterone concentrations between meat- and layer-type neonatal chicks (Gallus gallus) (1) exposed to isolation-induced stress or (2) injected intracerebroventricularly (ICV) with corticotropin-releasing factor (CRF). Both types of neonatal chicks housed in groups were individually introduced to an open field arena and locomotion and distress-induced vocalizations were monitored for 10 min. The responses of the two strains were remarkably different, with meat-type chicks being less active than layer-type chicks. Distress-induced vocalizations were drastically decreased over time in meat-type chicks while they remained high in layer-type chicks throughout the test. Plasma corticosterone concentrations measured at the end of the test were significantly higher in layer-type chicks than in meat-type ones. Plasma corticosterone concentrations measured 10 min after the ICV injection of CRF were significantly higher in layer- than meat-type chicks. These results indicate that meat-type chicks have either a greater capability to acclimatize to novel environments, or a blunted HPA axis compared with layer-type chicks.
Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
Shin
S
Saito
Tetsuya
T
Tachibana
Yang-Ho
YH
Choi
D Michael
DM
Denbow
Mitsuhiro
M
Furuse
D000818:Animals; D002645:Chickens / Q000097:blood*; D003345:Corticosterone / Q000097:blood*; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D013315:Stress, Psychological / Q000097:blood*
D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone