Effects of tail docking and castration on stress responses in lambs and the influence of prenatal glucocorticoid treatment.
It is common practice in Australian agriculture to remove the tails of lambs to prevent infection and to castrate males to prevent behavioural problems and unwanted reproduction. We have studied the pain and stress responses to these interventions by measuring changes in the hypothalamic-pituitary-adrenal (HPA) axis and β-endorphin levels. Further, we have evaluated the effects of prenatal exposure to dexamethasone, which is known to affect the developing HPA axis. In control animals that had received prenatal saline treatment, plasma cortisol and adrenocorticotrophin (ACTH) levels increased after the interventions in both females and males. Plasma β-endorphin levels also increased after the interventions, but the responses were less consistent. Prenatal dexamethasone exposure early in pregnancy (dexamethasone 0.14 mg kg(-1) ewe weight injection commenced on day 40 of pregnancy for four consecutive intramuscular injections at 12-hourly intervals) blunted the cortisol response to tail docking in female offspring, but not to combined tail docking and castration in males. It had no effect on ACTH or β-endorphin responses in either sex. These findings describe the stress responses to these common agricultural interventions and suggest that long-term development of the HPA axis in females is altered by prenatal exposure to dexamethasone.
School of Women's and Infants' Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. shaofu.li@uwa.edu.au
Shaofu
S
Li
Ilias
I
Nitsos
Graeme R
GR
Polglase
John P
JP
Newnham
John R G
JR
Challis
Timothy J M
TJ
Moss
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000383:Agriculture / Q000379:methods; D000818:Animals; D001315:Australia; D003907:Dexamethasone / Q000008:administration & dosage; D005260:Female; D005865:Gestational Age; D005938:Glucocorticoids / Q000008:administration & dosage*; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D008297:Male; D008431:Maternal-Fetal Exchange; D009919:Orchiectomy / Q000662:veterinary*; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000662:veterinary; D012756:Sheep / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D013623:Tail / Q000601:surgery*; D001615:beta-Endorphin / Q000097:blood
D005938:Glucocorticoids; D001615:beta-Endorphin; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone