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The effects of equine somatotropin (eST) on follicular development and circulating plasma hormone profiles in cyclic mares treated during different stages of the estrous cycle.
Domest Anim Endocrinol. 1999 Jan; 16(1):57-67.DA

Abstract

The effects of exogenous equine somatotropin (eST) administration on ovarian activity and plasma hormone levels were evaluated on horse and pony mares. The objectives of this study were to determine the effects of eST on follicular development and circulating concentrations of leutinizing hormone (LH), estradiol, progesterone, and insulin-like growth factor I (IGF-I) in cyclic horse and pony mares. Sixteen mares received daily injections (i.m.) of eST at a concentration of 25 micrograms/kg body weight on either Days 6 through 12 (Treatment A) or 13 through 19 (Treatment B) postovulation. In addition, contemporary mares were similarly given the carrier vehicle and served as controls (Treatments C and D). Blood samples were collected at 24-hr intervals and ultrasonographic evaluations were performed on the ovaries of each mare at 48-hr intervals beginning on the first day of treatment and ending either on the day of ovulation or 5 d postovulation. Circulating levels of insulin-like growth factor-I (IGF-I) were increased in treated mares by Day 3 post-treatment (P < 0.05). Also, mares in Treatment B exhibited a decrease in plasma estradiol concentrations (P < 0.05) when compared with control mares on Days 1 through 5 postovulation of the post-treated estrous cycle. In addition, circulating leutinizing hormone levels were different for mares in Treatment A compared with controls on Days--8 through--1 pre-ovulation (P < 0.05). All follicles present on the ovaries of each mare were measured and placed into one of five categories based on their diameter. Neither the mean number of follicles per size category > or = 8 mm in diameter nor the mean follicular diameter within each size category differed among treatment and control mares. However, eST treatment significantly increased the number of follicles < or = 7 mm on the ovaries of mares treated early in the estrous cycle when compared with control mares on Days 3 and 7 post-treatment and at the onset of standing estrus.

Authors+Show Affiliations

Department of Animal Science, Louisiana State University, Baton Rouge 70803, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10081663

Citation

Cochran, R A., et al. "The Effects of Equine Somatotropin (eST) On Follicular Development and Circulating Plasma Hormone Profiles in Cyclic Mares Treated During Different Stages of the Estrous Cycle." Domestic Animal Endocrinology, vol. 16, no. 1, 1999, pp. 57-67.
Cochran RA, Leonardi-Cattolica AA, Sullivan MR, et al. The effects of equine somatotropin (eST) on follicular development and circulating plasma hormone profiles in cyclic mares treated during different stages of the estrous cycle. Domest Anim Endocrinol. 1999;16(1):57-67.
Cochran, R. A., Leonardi-Cattolica, A. A., Sullivan, M. R., Kincaid, L. A., Leise, B. S., Thompson, D. L., & Godke, R. A. (1999). The effects of equine somatotropin (eST) on follicular development and circulating plasma hormone profiles in cyclic mares treated during different stages of the estrous cycle. Domestic Animal Endocrinology, 16(1), 57-67.
Cochran RA, et al. The Effects of Equine Somatotropin (eST) On Follicular Development and Circulating Plasma Hormone Profiles in Cyclic Mares Treated During Different Stages of the Estrous Cycle. Domest Anim Endocrinol. 1999;16(1):57-67. PubMed PMID: 10081663.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of equine somatotropin (eST) on follicular development and circulating plasma hormone profiles in cyclic mares treated during different stages of the estrous cycle. AU - Cochran,R A, AU - Leonardi-Cattolica,A A, AU - Sullivan,M R, AU - Kincaid,L A, AU - Leise,B S, AU - Thompson,D L,Jr AU - Godke,R A, PY - 1999/3/19/pubmed PY - 2001/3/28/medline PY - 1999/3/19/entrez SP - 57 EP - 67 JF - Domestic animal endocrinology JO - Domest. Anim. Endocrinol. VL - 16 IS - 1 N2 - The effects of exogenous equine somatotropin (eST) administration on ovarian activity and plasma hormone levels were evaluated on horse and pony mares. The objectives of this study were to determine the effects of eST on follicular development and circulating concentrations of leutinizing hormone (LH), estradiol, progesterone, and insulin-like growth factor I (IGF-I) in cyclic horse and pony mares. Sixteen mares received daily injections (i.m.) of eST at a concentration of 25 micrograms/kg body weight on either Days 6 through 12 (Treatment A) or 13 through 19 (Treatment B) postovulation. In addition, contemporary mares were similarly given the carrier vehicle and served as controls (Treatments C and D). Blood samples were collected at 24-hr intervals and ultrasonographic evaluations were performed on the ovaries of each mare at 48-hr intervals beginning on the first day of treatment and ending either on the day of ovulation or 5 d postovulation. Circulating levels of insulin-like growth factor-I (IGF-I) were increased in treated mares by Day 3 post-treatment (P < 0.05). Also, mares in Treatment B exhibited a decrease in plasma estradiol concentrations (P < 0.05) when compared with control mares on Days 1 through 5 postovulation of the post-treated estrous cycle. In addition, circulating leutinizing hormone levels were different for mares in Treatment A compared with controls on Days--8 through--1 pre-ovulation (P < 0.05). All follicles present on the ovaries of each mare were measured and placed into one of five categories based on their diameter. Neither the mean number of follicles per size category > or = 8 mm in diameter nor the mean follicular diameter within each size category differed among treatment and control mares. However, eST treatment significantly increased the number of follicles < or = 7 mm on the ovaries of mares treated early in the estrous cycle when compared with control mares on Days 3 and 7 post-treatment and at the onset of standing estrus. SN - 0739-7240 UR - https://www.unboundmedicine.com/medline/citation/10081663/The_effects_of_equine_somatotropin__eST__on_follicular_development_and_circulating_plasma_hormone_profiles_in_cyclic_mares_treated_during_different_stages_of_the_estrous_cycle_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0739-7240(98)00046-0 DB - PRIME DP - Unbound Medicine ER -