Melatonin improves testicular haemodynamics, echotexture and testosterone production in Ossimi rams during the breeding season

Abstract

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.

Exogenous L-carnitine Administration Ameliorates the Adverse Effects of Heat Stress on Testicular Hemodynamics, Echotexture, and Total Antioxidant Capacity in Rams

“…In this study, there was a significant change in TEs; these changes might be due to increased testicular perfusion with blood. Moreover, the relation between the testicular echogenic and hemodynamic changes has been reported ( 25 ) and changes in TE affect the testicular functions ( 10 , 21 , 23 ). Explanation of increases in TE observed at 1 h might be attributed to the higher vascular irrigation.…”

“…Decreased testicular blood perfusion in heat-stress conditions was reported in rams ( 10 , 11 ) and goat buck ( 23 ). Several attempts have been reported to improve the testicular hemodynamics by administering exogenous treatments in rams and goat bucks with potential outcomes, that finally reflected on the whole male fertility, such as melatonin, gonadotropin-releasing hormone (GnRH), and luteinizing hormone (LH) ( 12 , 19 , 24 , 25 ). L-carnitine (LC) is a vitamin-like bioenergetic amino acid that exists ubiquitously in different tissue types, such as heart, skeletal muscle, testes, and epididymis.…”

Melatonin improves post‐thaw sperm quality after mild testicular heat stress in rams

“…This is apparently the first report regarding effects of melatonin injection on post-thaw sperm quality in rams exposed to mild testicular HS, with melatonin conferring post-thaw sperm with significantly better total and progressive motility, acrosome integrity and mitochondrial membrane potential, plus lower sperm abnormalities and DFI%. We injected melatonin 2 week before HS, as it needs 2-4 week to take effect (El-Shalofy et al, 2021Samir et al, 2020).…”

Ageing affects plasma steroid concentrations and testicular volume, echotexture and haemodynamics in rams

“…These differences might be, in part, due to the relatively higher levels of plasma estradiol‐17β in mature and aged rams, a potent vasodilator (Rosenfeld et al, 2002). The reduced RI and PI values were accompanied with subsequent increase in the testicular blood flow, which directly correlated with spermatogenesis and steroidogenesis (El‐Shalofy et al, 2021c; Hedia et al, 2019).…”