Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
Reprod Domest Anim. 2021 Nov;56(11):1456-1463. doi: 10.1111/rda.14010. Epub 2021 Sep 3.
The objective was to determine effects of a single parenteral dose of melatonin on testicular blood flow indices, testicular echogenicity and plasma testosterone concentrations in rams during the physiological breeding season. We hypothesized that melatonin enhances testicular blood flow, echogenicity and plasma testosterone concentrations during the breeding season in rams. During the breeding season, 12 sexually mature Ossimi rams were randomly allocated to either a melatonin group (n = 8) that received 18 mg of melatonin in 1 ml of corn oil (injected SC) or a control group (n = 4) that received 1 ml corn oil only. Blood collection and ultrasonographic assessment of the testes and supratesticular arteries were conducted immediately before treatment (W0) and once weekly for 6 weeks after melatonin injection (W1-W6). Mean plasma testosterone concentrations were greater (p < .05; at least 1 ng/ml) in the melatonin-treated group compared to the control group from W4 to W6 after treatment. A decrease (p < .05) in both resistive index (RI) and pulsatility index (PI) began 1 week after melatonin injection (W1) and persisted until the end of the experiment, with mean RI and PI values in the melatonin group lower (p < .05) than those in the control group on W3 and W4. Furthermore, plasma testosterone concentrations in melatonin-treated rams were inversely correlated to both RI and PI (r = -.7 and -.6, respectively, p < .01). Testicular echogenicity decreased (p < .05) 1 week after melatonin injection (W1) and remained lower (p < .05) in the melatonin-treated group compared to the control group until the end of the study (W6). In conclusion, melatonin administration significantly altered testicular blood flow and echogenicity and increased plasma testosterone concentrations in Ossimi rams during the breeding season.
目的是确定在生理繁殖季节中，单次给予褪黑素对公羊睾丸血流指数、睾丸回声和血浆睾酮浓度的影响。我们假设褪黑素可增强公羊在繁殖季节的睾丸血流、回声和血浆睾酮浓度。在繁殖季节，将 12 只性成熟的奥希米公羊随机分配到褪黑素组（n = 8）或对照组（n = 4）。褪黑素组接受 18 毫克褪黑素溶于 1 毫升玉米油（皮下注射），对照组仅接受 1 毫升玉米油。在治疗前（W0）和褪黑素注射后每周一次共 6 周（W1-W6）进行采血和睾丸及睾丸上动脉的超声评估。与对照组相比，治疗后第 4 周到第 6 周，褪黑素处理组的平均血浆睾酮浓度更高（p <.05；至少 1ng/ml）。褪黑素注射后 1 周（W1），阻力指数（RI）和搏动指数（PI）开始下降（p <.05），并持续至实验结束，褪黑素组的平均 RI 和 PI 值在第 3 周和第 4 周低于对照组（p <.05）。此外，褪黑素处理组的血浆睾酮浓度与 RI 和 PI 呈负相关（r = -.7 和 -.6，分别为 p <.01）。褪黑素注射后 1 周（W1），睾丸回声降低（p <.05），且褪黑素处理组直至研究结束（W6）仍低于对照组（p <.05）。结论：在繁殖季节，褪黑素给药可显著改变奥希米公羊的睾丸血流和回声，并增加血浆睾酮浓度。
