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Plasma beta‐endorphin and adrenocorticotrophin in young horses in training
Author(s) -
McCARTHY RN,
JEFFCOTT LB,
FUNDER JW,
FULLERTON M,
CLARKE IJ
Publication year - 1991
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1991.tb00736.x
Subject(s) - basal (medicine) , treadmill , medicine , endocrinology , hormone , plasma concentration , beta endorphin , period (music) , insulin , physics , acoustics
SUMMARY A controlled period of submaximal exercise on a treadmill was used as a standardised stress test in 6 young horses to monitor the effects of training. Circulating plasma concentrations of immunoreactive beta‐endorphin (IR β‐EP) were measured before, during and after the exercise period. The stress test was conducted on 3 occasions during an intensive training program lasting 14 weeks. In week 3 a marked increase in plasma IR β‐EP (P=0.003) was demonstrated as a result of training, but by the last exercise test performed in week 9 no significant increase in plasma IR β‐EP concentrations could be detected. During the training period the basal concentrations of plasma IR β‐EP significantly decreased (P=0.0059). Plasma adrenocorticotrophin (ACTH) did not increase during exercise, although there was a trend of decreasing basal plasma ACTH by the end of the training period. It was concluded that a standardised work test acted as a mild stress to unfit horses, but as the horses' fitness increased the hormonal response to exercise diminished. Basal plasma β‐EP concentrations were decreased with increasing fitness.