Browsing by Subject "Leptin"

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    Effects of the feeding level in early gestation on body reserves and the productive and reproductive performance of primiparous and multiparous sows
    (Elsevier, 2022-05-28) Carrión-López, M. José; Madrid, Josefa; Martínez-Miró, Silvia; Hernández, Fuensanta; Orengo, Juan; Producción Animal
    Early gestation may be the best period for sows to recover body reserve losses from previous lactation. The aim of this study was to investigate the effect of different levels of restricted feeding in early gestation on the body status, productive and reproductive performance, and hormonal-metabolic status of primiparous and multiparous sows. A total of 130 sows were randomly assigned to one of three feeding levels: Treatment I, which sows were fed at the level commonly used from day 3 to 28 of gestation (2.5 kg⋅d-1 of a diet with 2.18 Mcal NE⋅kg-1 and 13.72 g CP⋅kg-1), and Treatments II and III, where feed was increased by 25% and 50%, respectively. Sow body status, litter size and weight, early mortalities, reproductive rates, weaning-to-estrus interval, and hormones linked to metabolism were recorded. The highest weight gain, body condition score, and backfat thickness were found in sows fed Treatment III compared to those fed the usual feeding level (Treatment I). No differences among treatment groups were found in litter size or litter weight, although a tendency for more live born piglets and fewer stillbirths was found in sows fed Treatment III. In contrast, litters from sows fed at higher feeding levels had a higher mortality at 72 h compared to those fed at the lowest feeding level (I), which was partly linked to a higher percentage of piglets culled at birth and piglets weighing less than 800 g. There were no differences in conception and farrowing rates, leptin, progesterone, insulin, or cortisol among treatment groups applied in early gestation. In conclusion, increasing the feeding level in sows during early gestation to improve their short-term productive and reproductive performance remains controversial. Further studies are needed to focus on how the restricted feeding level applied could affect the viability and proportion of low-weight piglets.
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    Histological assessment for femora of ovariectomized obesity (db/db) mice carrying mutated leptin receptor
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2016) Tanaka, Yusuke; Hasegawa, Tomoka; Yamada, Tamaki; Yamamoto, Tomomaya; Sasaki, Muneteru; Hongo, Hiromi; Tsuboi, Kanako; Haraguchi, Mai; Luiz de Freitas, Paulo Henrique; Li, Minqi; Oda, Kimimitsu; Totsuka, Yasunori; Tei, Kanchu; Amizuka, Norio
    In order to provide a clue to understand the interplay between leptin and estrogen, we have examined femoral metaphyses of ovariectomized db/db mice carrying a mutated leptin receptor. We performed ovariectomy (OVX) or sham-operation (sham) on 12- week old female wild-type and db/db mice, and then, after 8 weeks, divided the animals into four groups: wild-type sham, wild-type OVX, db/db sham and db/db OVX. Samples from all groups were prepared for histochemical and ultrastructural examinations. As a result, db/db sham mice showed a reduced number and thickness of metaphyseal trabeculae and excessive adipose tissue when compared to wild-type sham mice. The wild-type OVX group exhibited markedly diminished trabecular number, as well as lower populations of osteoblasts and osteoclasts in comparison to wild-type sham group. On the other hand, trabecular numbers were similar for the two db/db groups, suggesting that the effect of the ovariectomy, i.e., estrogen deficiency may be lessened in this animal model. Leptin receptor was mainly found in osteoblasts and in bone marrow stromal cells including adipocytes. In addition, the expression of estrogen receptor did not seem to change after OVX in wild-type mice and in db/db mice. Both db/db sham and OVX mice featured many adipocytes close to the metaphyseal chondroosseous junction, while osteoblasts accumulated glycogen granules and lipid droplets. Therefore, it seems likely that the disruption of leptin signaling in db/db mice shifts the cell differentiation cascade towards the adipocyte lineage, resulting in an osteoporotic bone independently of estrogen deficiency.
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    Leptin secretion by white adipose tissue and gastric mucosa
    (Murcia : F. Hernández, 2007) Cammisotto, P.G.; Bendayan, M.
    Leptin is a hormone that plays a central role in the regulation of food intake and energy expenditure. Originally discovered in mature white adipocytes, it was subsequently isolated from the gastric mucosa. This tissue contains a large number of epithelial endocrine and exocrine cells secreting leptin in the blood stream and in the gastric lumen, respectively. Light and electron microscopy have shown that adipocytes and gastric epithelial cells contain leptin along their rough endoplasmic reticulum-Golgi-granules secretory pathway. Both tissues synthesize a soluble form of the leptin receptor that is secreted bound to leptin in the blood and into the gastric juice. This soluble receptor protect leptin and enhances its half-life. Despite the similarities in the mechanisms of leptin secretion by adipocytes and gastric epithelial cells, they are in fact radically different. In gastric cells leptin follows a rapid regulated secretion pathway whereas adipocytes secrete leptin in a constitutive slow fashion. These differences can be explained by the specific roles play by leptin originating from these two different tissues. Gastric leptin is involved in the short-term regulation of digestion, including delay of gastric emptying, absorption of nutrients by the intestinal wall and secretion of gastric, intestinal and pancreatic hormones. On the other hand, leptin secreted by white adipocytes acts primarily on the hypothalamus for the long-term regulation of food intake. Therefore, the coordination of adipose and gastric leptins ensures the proper management of food processing and energy storage.