Effects of myiasis and acute [handling] restraint stress on plasma levels of immunoreactive beta-endorphin, adrenocorticotrophin (ACTH) and cortisol in the sheep [Lucilia cuprina]
1988
Shutt, D.A. | Connell, R. | Fell, L.R. (New South Wales Dept. of Agriculture, Richmond (Australia). Hawkesbury Agricultural Research Unit) | Smith, A.I. | Wallace, C.A. (Prince Henry's Hospital, Melbourne (Australia). Medical Research Centre)
Sixteen Merino wethers were exposed to handling restraint, and blood sampling, during examination for blowfly strike; where necessary, they were treated for cutaneous myiasis. Significant changes in the plasma concentrations of immunoreactive beta-endorphin (beta-EP), ACTH and cortisol were found in sheep with extensive myiasis, as compared with unstruck sheep or those with only localized myiasis. Whereas significant increases in plasma ACTH and cortisol can result from pituitary-adrenal responses to acute emotional or surgical stress, and are usually accompanied by a concomitant release of beta-EP from the pituitary, the present findings indicate a marked reduction in beta-EP levels and a significant increase in ACTH and cortisol in sheep following blowfly strike and acute handling restraint. This result suggests that cutaneous myiasis in susceptible sheep can alter the pituitary-adrenal response to acute restraint stress, and this could occur either by an alteration of precursor processing the pituitary or by the selective release of ACTH.
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