Changes in thyroid hormones, leptin, ghrelin and, galanin following oral melatonin administration in intact and castrated dogs: a preliminary study

Abstract

Background Melatonin regulates metabolism and metabolism related hormones in mammalians. Castration has some adverse effects on the metabolic hormones of dog. This study was conducted to determine the effects of oral melatonin administration on metabolic hormones, as well as to compare changes of these hormones after administration of melatonin in castrated and intact dogs. Twenty healthy mixed breed mature male dogs were divided randomly into four groups ( n = 5): melatonin (3 mg/10 kg(, castrated, castrated and melatonin treated, and negative control. Blood sample was collected from jugular vein weekly for 1 month. Results T3 and T4 hormones had a significant decrease within 1 month following administration of melatonin. No significant change was observed in concentration of FT3 and FT4 hormones. Leptin and ghrelin hormones also had a significant decrease in this period. Leptin and ghrelin had a more significant decrease in “non-castrated and melatonin treated” group compared to “castrated and melatonin treated” group. Galanin had a significant decrease but this neurotransmitter had no significant change in “non-castrated and melatonin treated” group in comparison to “castrated and melatonin treated” group. Conclusions It seems that daily administration of melatonin capsule in all dogs can probably decrease concentration of T3 and T4 hormones and balance other metabolic hormones following castration. Methods The dogs underwent castration, melatonin treatment and blood sampling.

The Effects of Melatonin Treatment on Oxidative Stress Induced by Ovariohysterectomy in Dogs

“…Their results showed that melatonin increased the level of serotonin but decreased the level of cortisol in intact and castrated dogs [16]. Taheri et al (2019) also studied the effects of melatonin administration on the levels of thyroid hormones, leptin, and ghrelin in intact and castrated male dogs. They observed that melatonin could regulate metabolic hormones and mitigate the metabolic side-effects of castration [18].…”

“…Taheri et al (2019) also studied the effects of melatonin administration on the levels of thyroid hormones, leptin, and ghrelin in intact and castrated male dogs. They observed that melatonin could regulate metabolic hormones and mitigate the metabolic side-effects of castration [18]. Furthermore, melatonin has been shown to regulate the activation or inhibition of several transcription factors related to antioxidant response, which can justify the antioxidative effects of this substance [29].…”

“…As in our previous studies, melatonin was administrated daily just before and after spaying. Also, since the effect of anesthesia on oxidative stress had to be examined in comparison with other groups [16][17][18][19], the dogs were divided into ve equal groups (n = 5) in a case-control randomized study (Fig. 1).…”

“…Under special conditions, the neuroendocrine cells of other organs, including the thyroid gland, retina, skin, and gastrointestinal tract, can also produce melatonin in vertebrates [15]. In our previous experiments, we found that melatonin could have anti-oxidative, anti-in ammatory, and anti-stress effects and regulate the secretion of metabolic hormones in dogs following castration [16][17][18][19].…”

Removal of melatonin receptor type 1 signalling induces dyslipidaemia and hormonal changes in mice subjected to environmental circadian disruption

“…36 The serum ghrelin level peaks during the resting phase and is mainly regulated by food intake. 37,38 Some studies have also reported that melatonin also decreases ghrelin levels in dogs and rats, 39,40 while in humans, plasma melatonin concentration correlated negatively with ghrelin, thus suggesting a possible role for melatonin in the regulation of ghrelin concentration. 41 Ghrelin is also a key regulator in glucose homeostasis, and it regulates insulin secretion via heterodimerization of G-protein-coupled receptor GSH-R and somatostatin-5 42 ; this could explain why MT 1 KO females have an increase in plasma insulin after ECD.…”