Serum concentrations of leptin in pregnant and non‐pregnant bitches

Abstract

Leptin regulates body weight and several physiological processes including reproduction. We evaluated the circulating levels of leptin in pregnant and non‐pregnant bitches as well as their correlation with body weight, food intake and number of foetuses. Nineteen healthy German shepherd bitches were used and divided in two groups (pregnant n = 12 and non‐pregnant n = 7). Blood samples were collected every 15 days starting from ovulation (Day 0) throughout pregnancy (pregnant group, P) or throughout luteal phase (non‐pregnant group, NP) In pregnant bitches, leptin concentrations increased from the day of ovulation (1.32 ± 0.06 ng/ml) up to day 45 (1.51 ± 0.06 ng/ml; p < .01) and returned to baseline values from day 60 post‐ovulation. In non‐pregnant bitches, leptin concentrations remained constant throughout the whole observation period (estimated marginal mean ± SE=1.33 ± 0.38 ng/ml). Pairwise comparisons showed significant differences between P and NP at day 45 post‐ovulation (p < .05). Multivariable models indicated that, controlling for time and litter size, there was a positive relationship between leptin concentration and BW (p < .05) although Pearson coefficients showed that the correlation between BW and leptin was only significant in NP animals at day 45 (r = 0.76, p < .05). The multivariable approach also suggested that, holding BW and time constant, leptin concentrations tend to increase as the number of puppies increased (p = .06). Our study supports indirectly the contribution of the feto‐placental unit to the circulating maternal leptin concentration.

Impact of Goji Berries (Lycium barbarum) Supplementation on the Energy Homeostasis of Rabbit Does: Uni- and Multivariate Approach

“…By using weekly sampling, these authors highlighted short-term changes during pregnancy, especially in insulin and leptin. These changes suggested a condition of insulin and leptin resistance that characterizes the pregnancy of many mammals including women [30,32,[42][43][44][45]. In the present study, the changes were assessed at longer intervals but the concentrations at early and late pregnancy were comparable to those of Menchetti et al [31].…”

“…In fact, during this physiological status, the pregnant animal enhances the feed intake and the mobilization of the body reserves as an adaption mechanisms to the modification in energetic request [26][27][28]. Different hormones (insulin, leptin, T3, T4 and cortisol) and metabolites such as glucose and non-esterified fatty acids (NEFA) are implicated in maintaining energy homeostasis during pregnancy in different species [29][30][31][32]. To our knowledge, no studies have evaluated the impact of the goji berries enriched diet on the hormonal control of the energetic homeostasis during pregnancy of the rabbit does.…”

Energy homeostasis in rabbit does during pregnancy and pseudopregnancy

“…Leptin could also have functions in the metabolic allocation of nutrients during the transition from pregnancy to lactation, when the energetic priority shifts from the building of energetic stores within the body to the release of energy from these stores (Block et al, 2001). Results of the present study indicated leptin concentrations return to concentrations similar to those of PP does during late pregnancy and after birth which also occurs in women, bitches, and cows but not in ewes (Block et al, 2001;McFadin et al, 2002;Pérez-Pérez et al, 2018;Troisi et al, 2020).…”

“…Plasma leptin concentrations are greater in P compared with PP does, particularly in the second and third week of pregnancy (about +20%). There is also this leptin pattern in women, rodents, cows, and bitches (Kawai et al, 1997;Block et al, 2001;Reitman et al, 2001;Cardinali et al, 2017;Troisi et al, 2020); however, both the biological and physiological functions of leptin appear to be species-specific during pregnancy. The increase observed in the P does appears to be lesser than in other species.…”

“…In women, compared to the adipose tissue leptin production (Reitman et al, 2001;Pérez-Pérez et al, 2018), placental leptin production contributes to pregnancy hyperleptinemia; on the contrary in rats and mice, the placenta is not a major source of leptin (Kawai et al, 1997;Gustafson et al, 2019). Troisi et al (2020) have recently reported that leptin concentrations increase proportionally with the number of puppies that are in utero in bitches, suggesting a contribution of the feto-placental units to the maternal leptin. The contribution of the placenta and the adipose tissue to circulating leptin concentrations in rabbit does remains to be further investigated, because in the present study, there was no association between the number of rabbit kits born and leptin concentration.…”