Endocrine and reproductive characteristics in sheep and cattle following exposure to Acacia berlandieri sympathomimetic amines and/or adrenocorticotropic hormone (ACTH)-induced cortisol elevation /
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Toxic plants occur on ranges throughout Texas. Acacia berlandieri offers nutritious browse, yet toxic effects may occur due to sympathomimetic actions of phenolic amines. Elevated stress hormones can alter reproductive function. Experiments (Exps. 1,2,3,4) were conducted to evaluate effects of phenolic amines, or exogenous ACTH, on reproductive processes. In Exp.1, wethers treated with N-methyl-β-phenethylamine (NMPA) at 0 (NMPAO), 2 (NMPA2) and 4 (NMPA4) mg/kg BW had norepinephrine (NE) peak times (PKTS) of 34.5, 17.8 and 3.6 min, respectively (P <.06). No effects on LH post-GnRH challenge (500 ng) were detected. Exp. 2 revealed a lower (P <.06) LH peak amplitude (PKAMP) following GnRH in NMPA2 vs NMPA0 and NMPA4 wethers. In NMPA2 wethers, PKT was more rapid (P <.05), and cortisol PKAMP was greater (P <.05). In Exp. 3, LH peak height (PKHT), PKAMP, and mean concentration post-GnRH, were inhibited (P <.05) for both NMPA and NMPA + tyramine (NMPA+T) vs Control animals Conversely, NMPA and NMPA+T animals had greater mean cortisol concentration (P <.06), PKAMP (P <.05) PKHT (P <.09) and greater (P <.08) NE concentration, and more rapid (P <.05) NE PKT. In Exp. 4, heifers were treated with either saline (Control), 2 mg/kg BW MNPA, or with 80 IU of ACTH, twice daily during a 4 d superovulation regimen. Blood samples were collected pre and post-treatment. Cortisol response was greater (P <.05) in ACTH and NMPA vs Control heifers. Ultrasonography revealed no overall effects on pools of small (<4mm), large (> 8mm), or total follicles. On d 2 and 3 there were fewer medium (4-8 mm) follicles in NMPA heifers. On d 4, there were fewer medium follicles in ACTH heifers. Control heifers exhibited standing estrus earlier (P <.05) vs NMPA or ACTH heifers. Reproductive dysfunctions (estrus absent, ovulation absent, CL formation absent; P4 <1 ng/ml) were more frequent (P <.05) in NMPA (5/11) vs ACTH (2/12) or Control (0/10) heifers. Neither NMPA nor ACTH affected mean number of embryos or their quality. Plant phenolic amines may induce sympathetic responses with subsequent inhibition of LH-dependent reproductive processes. |
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| Item Description: | Vita. "Major subject: Physiology of Reproduction." |
| Physical Description: | xv, 113 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |