ACTH-induced stress in weaned sows impairs LH receptor expression and steroidogenesis capacity in the ovary.

H S Zhu,E D Bao,H L Liu,Z Qian

doi:10.1186/s12958-016-0214-5

Abstract

BackgroundStress has been proved to impair the porcine reproduction soundly. Endocrine disruption, which is closely related to the persistent follicles, is possibly one of the results of stress, although the mechanism is unclear. Since the expression of luteinizing hormone receptor (LHR) in ovarian follicular wall and concentrations of steroid hormone in follicular fluid are related to the development of persistent follicles, this study is designed to evaluate the effect of administered adrenocorticotrophic hormone (ACTH) to weaned pigs on their ovarian steroidogenesis capacity and LHR expression.MethodsTen multiparous sows were weaned and randomly divided into two groups (n = 5 each). Sows received 1 IU/kg ACTH (ACTH group) or saline (control group) every 8 h from days 3–9 after jugular vein intubation. Blood samples were collected throughout the experiment, and ovaries were collected after slaughter on day 10. Follicular fluid (FF) was used to determine the steroid hormone concentrations. The ovarian follicle wall was obtained and stored in liquid nitrogen to detect mRNA levels.ResultsThe plasma cortisol concentration was significantly (P < 0.01) elevated after ACTH injection. The estradiol (E2) and androstenedione (ASD) concentrations in FF were significantly lower (P < 0.05) in the ACTH group than in the control group. The LHR, 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome P450 aromatase (P450arom), and cytochrome P450 17a-hydroxylase (P450c17) mRNA levels were significantly (P < 0.05) reduced in the ACTH group. The steroidogenic acute regulatory protein (StAR) level and cytochrome P450 side-chain cleavage (P450scc) was lower in the ACTH group than in the control group, but the difference was not statistically significant (P > 0.05). Immunostaining results revealed 3β-HSD,P450c17, and LHR expression in theca cells, and P450arom expression in granulosa cells. Immunohistochemical staining showed significant differences in the distribution of 3β-HSD, P450c17, LHR, and P450arom between the two groups.ConclusionsThese findings indicated that ACTH significantly diminished the LHR expression and steroidogenesis capacity of the ovaries of weaned sows.

Highlights

Stress has been proved to impair the porcine reproduction soundly
Plasma cortisol concentrations in the adrenocorticotrophic hormone (ACTH) and control groups We evaluated the plasma cortisol levels in sows in the ACTH and control groups at four different time points in order to evaluate their stress levels (Fig. 1)
The results revealed that plasma cortisol levels were maintained at a high level in the ACTH group, indicating successful stress induction in the ACTH model group

Summary

Introduction

Endocrine disruption, which is closely related to the persistent follicles, is possibly one of the results of stress, the mechanism is unclear. A previous study found that ovarian cysts are an important disorder for sows, which accounted for 10% of reproductive problems in pigs [4]. Little is known about ovarian cysts, because it may happen without the performance of reproduction confusion [4]. Stress results in alterations in hormonal events along with the immediate endocrine; some studies have reported that endocrine imbalance is the primary reason for the occurrence of ovarian cysts [6, 7]. Many events can potentially cause stress and it is difficult to assess the precise relationship between stress and reproduction due to the varied number and type of stressors

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