Department of Animal Reproduction and Veterinary Radiology, Faculty of Veterinary Medicine and Animal Science, FMVZ, Universidade Estadual Paulista "Júlio de Mesquita Filho", UNESP, Botucatu, SP, Brazil.
Department of Animal Reproduction and Veterinary Radiology, Faculty of Veterinary Medicine and Animal Science, FMVZ, Universidade Estadual Paulista "Júlio de Mesquita Filho", UNESP, Botucatu, SP, Brazil.
Theriogenology. 2019 Dec;140:93-98. doi: 10.1016/j.theriogenology.2019.08.024. Epub 2019 Aug 21.
Tricyclic antidepressives, such as imipramine, indirectly induce ejaculation by increasing the noradrenaline concentration, which triggers an α-adrenergic response, whereas α-adrenergic agonists, such as xylazine and detomidine, directly trigger ejaculation by activating the α-1 adrenergic receptors. Furthermore, serum oxytocin concentrations in stallions increase drastically before ejaculation, but decline immediately thereafter, implicating the role of this hormone in emission. The objectives of the present study were to: 1) compare the efficiency of various protocols for inducing ex copula ejaculation in stallions, 2) evaluate the benefits of including oxytocin in the protocols, and 3) compare the semen characteristics of ex copula versus in copula ejaculates. Nine protocols were used to induce ex copula ejaculation using various combinations of xylazine (X; 0.66 mg/kg, iv); oxytocin (O; 20 IU, iv), imipramine (I; 3 mg/kg, orally), and detomidine (D; 0.02 mg/kg, iv). Imipramine was given 2 h prior to the administration of α-adrenergic agonist (detomidine or xylazine) and oxytocin. If ejaculation did not occur within 10 min after treatment with an α-adrenergic agonist, a half-dose of the same product was injected. Twelve sexually mature stallions (6-26 y) were used; 9 of 12 stallions responded to the treatment. Two stallions responded to X or XO, four stallions responded to IX and IXO, one stallion responded to DO, and five responded to IDO. Stallions that responded to detomidine did not respond to xylazine. No stallion ejaculated in response to D, ID, or IO. Erections and masturbation occurred only in imipramine-treated stallions. Sperm quality was similar among all the protocols and was not significantly different from those in in copula ejaculates collected with an artificial vagina. In a separate trial, none of these protocols induced ex copula ejaculation in 2-3 y old stallions. The side effects included sialorrhea after imipramine administration in all the stallions and sedation after administration of xylazine or detomidine. In conclusion, the new protocol, IDO, and the traditional protocol, IX, had similar results, with IDO being a useful alternative protocol in stallions for which IX was not effective. Therefore, attempts using both the protocols are encouraged, as stallions that ejaculated upon administration of detomidine did not ejaculate when xylazine was administered, whereas those that responded to xylazine did not respond to detomidine.
三环类抗抑郁药，如丙咪嗪，通过增加去甲肾上腺素浓度间接诱导射精，从而引发 α-肾上腺素能反应，而 α-肾上腺素能激动剂，如二甲苯胺和地托咪定，通过激活 α-1 肾上腺素能受体直接触发射精。此外，公马在射精前血清催产素浓度急剧增加，但随后立即下降，这表明该激素在排放中起作用。本研究的目的是：1）比较各种方案诱导公马体外射精的效率，2）评估在方案中加入催产素的益处，3）比较体外与体内射精的精液特征。使用了 9 种方案，通过各种组合的二甲苯胺（X；0.66mg/kg，iv）；催产素（O；20IU，iv）、丙咪嗪（I；3mg/kg，口服）和地托咪定（D；0.02mg/kg，iv）来诱导体外射精。丙咪嗪在给予 α-肾上腺素能激动剂（地托咪定或二甲苯胺）和催产素前 2 小时给予。如果在使用 α-肾上腺素能激动剂治疗后 10 分钟内未发生射精，则注射相同产品的半剂量。12 匹性成熟的种马（6-26 岁）被使用；12 匹种马中有 9 匹对治疗有反应。2 匹种马对 X 或 XO 有反应，4 匹种马对 IX 和 IXO 有反应，1 匹种马对 DO 有反应，5 匹种马对 IDO 有反应。对地托咪定有反应的种马对二甲苯胺没有反应。没有种马对 D、ID 或 IO 有反应。勃起和手淫仅发生在丙咪嗪治疗的种马中。所有方案的精子质量相似，与人工阴道采集的体内射精无显著差异。在另一个试验中，这些方案都没有在 2-3 岁的种马中诱导体外射精。副作用包括所有种马在给予丙咪嗪后出现流涎，以及给予二甲苯胺或地托咪定后出现镇静。总之，新方案 IDO 和传统方案 IX 具有相似的结果，IDO 是一种在 IX 无效的情况下对种马有用的替代方案。因此，鼓励尝试这两种方案，因为接受地托咪定治疗后射精的种马在接受二甲苯胺治疗时不会射精，而对二甲苯胺有反应的种马则不会对地托咪定有反应。
