The effect of ergot alkaloid exposure during gestation on the microscopic morphology and vasculature of the ovine placenta

ABSTRACT

Ergot alkaloids, a class of mycotoxins associated with ergotism, act as agonists on serotonin (5HT) receptors, specifically 5HT2a, which mediate smooth muscle contraction and vasoconstriction. The objective of this study was to examine the impact of ergot alkaloid exposure during mid and late gestation on microscopic placental structure and vascular development. Ewes were fed endophyte-infected tall fescue seed containing ergot alkaloids (E+/E+, 1.77 mg ewe⁻¹ d⁻¹) or endophyte-free tall fescue seed (E-/E-, 0 mg ergot alkaloids) during both mid (d 35 to d 85) and late gestation (d 86 to d 133). On d 133 of gestation, a terminal surgery was performed and two placentomes of the type B morphology were collected for microscopic analyses. Amorphous connective tissue regions were larger (p < 0.0001) and more numerous (p = 0.025) in the placentome of ergot alkaloid exposed ewes. Staining showed no difference (p = 0.83) in the number of vessels present, but luminal area of maternal vasculature was 117% greater (p < 0.0001) in ergot alkaloid exposed ewes. Results showed that exposure to ergot alkaloids during gestation slowed maturation of the fetal villi as indicated by greater amorphous connective tissue regions, and altered size and shape of blood vessels to counteract reductions in blood flow caused by vasoconstriction.

KEYWORDS:

• Sheep
• ergot alkaloids
• placental structure
• vascular development

Acknowledgments

Appreciation is expressed to: M. C. Miller for animal handling, R. Smith for laboratory assistance, and C. Piatak and B. Pinckney for assistance with image analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Technical Contribution No. 6579 of the Clemson University Experiment Station. This research was supported, in part, by United States of Agriculture - National Institute of Food and Agriculture [Grant no. 2015-67015-23218]. The research reported in this publication was conducted using a Leica 6500 Laser Microdissection system and a Leica SP8X Confocal multiphoton/HyVolution microscope system, both housed in the Clemson Light Imaging Facility (CLIF). CLIF is supported, in part, by the Clemson University Division of Research, NIH [Award #P20GM109094], and NIH [Award #5P20RR021949-03]; Equipment funding was provided in part by NSF MRI Award #0722841, NSF Award #IOS-1444461, NSF MRI Award #1126407. The content of this material and any opinions, findings, conclusions, or recommendations expressed in this material is solely the responsibility of the author(s) and does not necessarily represent the official views of the National Institutes of Health or the National Science Foundation.