6 research outputs found
Expression of leptin and adiponectin in the rat oviduct
SUMMARY In mammals, the oviduct is an important source of factors that play key roles in
reproductive and developmental events. The major components of oviduct fluid are oviductspecific
glycoproteins, but other proteins are synthesized and secreted by the oviduct epithelium.
Leptin and adiponectin are two hormones originally identified in adipocytes that
play a critical role not only in the control of energy balance and metabolism but also in diverse
functions such as reproduction. This study investigates the presence and distribution of
leptin and adiponectin in the rat oviduct through a combination of immunohistochemistry
and reverse transcription–polymerase chain reaction techniques. Using both techniques, it
has been detected that the oviduct of cycling rats expresses leptin and adiponectin. Immunoreactivity
for both adipokines appears in the apical region of the secretory epithelial cells,
only in the isthmus and ampulla. The immunostain is stronger in the isthmus and changes
throughout the estrous cycle in the ampulla, increasing from proestrous to estrous. The results
presented here are a further contribution to the identification of leptin and adiponectin
produced and secreted by the oviduct epithelium, which must be taken into account for a
better understanding of the reproductive events that take place in this organ
Optimal bone strength and mineralization requires the type 2 iodothyronine deiodinase in osteoblasts
Hypothyroidism and thyrotoxicosis are each associated with an increased risk of fracture. Although thyroxine (T4) is the predominant circulating thyroid hormone, target cell responses are determined by local intracellular availability of the active hormone 3,5,3′-L-triiodothyronine (T3), which is generated from T4 by the type 2 deiodinase enzyme (D2). To investigate the role of locally produced T3 in bone, we characterized mice deficient in D2 (D2KO) in which the serum T3 level is normal. Bones from adult D2KO mice have reduced toughness and are brittle, displaying an increased susceptibility to fracture. This phenotype is characterized by a 50% reduction in bone formation and a generalized increase in skeletal mineralization resulting from a local deficiency of T3 in osteoblasts. These data reveal an essential role for D2 in osteoblasts in the optimization of bone strength and mineralization