Effects of Androgen on Plasma Levels of Adrenocorticotropic Hormone and Cortisol during Transportation in Goats

Abstract

ABSTRACT. Previously, we demonstrated that plasma cortisol (Cor) levels were increased by road transportation in castrated male goats, but the extent of the increase was significantly reduced by 5α-dihydrotestosterone (DHT) implantation. This study aims to clarify whether the reduction of Cor secretion by androgen during transportation results from reduced plasma adrenocorticotropic hormone (ACTH). Castrated goats were implanted separately with cholesterol (Cho), testosterone (T) or DHT, followed by transportation. Plasma Cor levels increased during transportation regardless of hormone treatment, but the levels in T and DHT treated animals were lower than those in animals treated with Cho. Plasma ACTH levels also increased during transportation, and those in T treated animals were significantly lower than in those treated with Cho. However, plasma ACTH levels in DHT treated animals varied among the animals and did not differ from those in Cho treated animals. Significant and highly positive correlations between the logarithm of plasma ACTH levels and plasma Cor levels were found in every treatment group. The areas under the regression curves between plasma ACTH levels and plasma Cor levels associated with T and DHT treatments were significantly lower than those with Cho treatment. In conclusion, T was shown to reduce ACTH secretion in response to transportation in castrated goats. However, this suppression of the increase in Cor secretion during transportation by androgen is suggested to be mainly a result of suppression of the responsiveness of the adrenal cortex to ACTH. KEY WORDS: ACTH, androgen, cortisol, goat, transportation stress.J. Vet. Med. Sci. 67(11): 1109-1114 Gonadal hormones can influence the stress responses of the hypothalamo-pituitary-adrenal (HPA) axis in rodents [6,7,11], humans [10,18,19] and domestic animals [1,4]. For example, our previous work indicates that androgen affects the increase in plasma cortisol (Cor) level induced by road transportation stress [1]. Although plasma Cor levels increase during road transportation in both male and female mature goats, those in males are significantly lower than those in females. We further demonstrated that the increase in plasma Cor levels during transportation was significantly reduced by 5α-dihydrotestosterone (DHT) in castrated male goats [1]. In addition, we have found that ovariectomized female goats show a similar response to DHT (unpublished data).The secretion of glucocorticoid is stimulated by adrenocorticotropic hormone (ACTH) secreted from the anterior pituitary gland. ACTH secretion is regulated by corticotropin-releasing hormone (CRH) secreted from the hypothalamus [20]. In rodents [6,7] and humans [18], the physiological mechanisms underlying the involvement of gonadal hormones in the HPA responses to stress are becoming clearer. For example, Handa and co-workers reported that castration of male rats enhances the increase in c-fos mRNA expression in the hypothalamic paraventricular nucleus (PVN) induced by the open field test, and an...

Androgen Suppresses Corticotropin-Induced Increase in Plasma Cortisol Level but Enhances The Increase in Plasma Aldosterone Level in Goats

“…We further demonstrated that androgen treatment reduced the transportation-induced increase in plasma Cor levels even when increase in plasma ACTH levels were not affected [1], and that androgen treatment reduced the increase in plasma Cor levels induced by adrenocorticotropic hormone (ACTH) administration in goats [13]. This report indicates that the suppression of transportationinduced increase in Cor secretion by androgen in goats is mainly a result of the suppression of the response of the adrenal cortex to ACTH, although androgen can affect Cor secretion by acting in the hypothalamus and/or the pituitary levels in some part [7].…”

“…Androgen treatment: Administration of androgens was carried out as described by Aoyama et al [1,2]. Each goat received hormone treatment 9 to 14 days prior to the experiment.…”

“…Our previous works reported that the increase in plasma cortisol (Cor) levels during road transportation, which can be a severe stress to domestic animals including goats [3,12,14], were significantly reduced by testosterone (T) or 5α-dihydrotestosterone (DHT) treatments in castrated male goats [1,2]. We further demonstrated that androgen treatment reduced the transportation-induced increase in plasma Cor levels even when increase in plasma ACTH levels were not affected [1], and that androgen treatment reduced the increase in plasma Cor levels induced by adrenocorticotropic hormone (ACTH) administration in goats [13].…”

Short‐term transportation in a small vehicle affects the physiological state and subsequent water consumption in goats

“…One may infer that goats still feel stress even after they have spent one hour in their own pen after the transportation has ended. However, previously we reported that one‐hour transportation increased markedly plasma adrenocorticotropic hormone (ACTH) levels but it was restored to basal levels within 30 min of the end of transportation, whereas plasma Cor levels still remained higher than in controls at this time (Aoyama et al . 2005).…”

Diseases of the Endocrine System

“…Glucocorticoids bind to cytosolic receptors in target tissues to increase gene transcription, increase protein catabolism, increase gluconeogenesis, inhibit inflammation through blockade of the arachidonic acid cascade, antagonize peripheral insulin sensitivity, and increase blood glucose. 183 Furthermore, male castrated animals treated with these androgens showed decreased blood cortisol response as compared with control animals consequent to ACTH administration, suggesting that such changes are mediated at the level of the adrenal gland. 181 Plasma cortisol increases related to the stress response are depressed in intact males as compared with females.…”