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Published on: October 2, 2018
Adenohypophyseal function in bitches treated with medroxyprogesterone acetate
N J Beijerink1, S F M Bhatti, A C Okkens
1Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. N.J.Beijerink@vet.uu.nl
Domestic Animal Endocrinology
|February 4, 2006
Summary
Medroxyprogesterone acetate (MPA) treatment in female dogs suppressed estrus and ovulation. While it increased FSH and IGF-1, MPA suppressed the adrenal axis and did not affect LH, prolactin, or alpha-MSH secretion.
Area of Science:
- Veterinary Endocrinology
- Reproductive Physiology
- Canine Health
Background:
- Medroxyprogesterone acetate (MPA) is a synthetic progestin used for reproductive control.
- Its effects on the canine adenohypophyseal axis require detailed investigation.
Purpose of the Study:
- To evaluate the impact of chronic MPA administration on the function of the canine adenohypophysis.
- To assess the secretion of key pituitary hormones and their responses to hypothalamic stimulation.
Main Methods:
- Five Beagle bitches received MPA (10mg/kg, every 4 weeks) for 11 months.
- A combined adenohypophyseal function test was performed, administering CRH, GHRH, GnRH, and TRH.
- Plasma hormone levels (ACTH, cortisol, GH, IGF-1, LH, FSH, prolactin, alpha-MSH, TSH) were measured before and during MPA treatment.
Main Results:
- MPA successfully prevented estrus and ovulation.
- Significant increases in FSH and IGF-1 were observed, alongside suppression of the hypothalamic-pituitary-adrenocortical axis (decreased cortisol response).
- LH secretion remained unaffected, while prolactin and alpha-MSH were unchanged; TSH showed a slight increase.
Conclusions:
- Chronic MPA treatment in dogs alters adenohypophyseal function, notably increasing FSH and IGF-1 secretion.
- MPA effectively suppresses reproductive cycles and the adrenal axis while maintaining LH, prolactin, and alpha-MSH levels.
- These findings provide insights into the endocrine effects of MPA in canines.
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