The role of leptin in female reproduction is fairly well established in mammals, whereas reports concerning leptin action in birds are scarce. The aim of the present study was to detect leptin receptor (LEP-R) mRNA and to localize the leptin receptor protein in the oviduct of laying hens 2h after ovulation by the RT-PCR method and immunocytochemical staining. The RT-PCR reaction demonstrated expression of the long form of leptin receptor mRNA in all examined oviductal parts (infundibulum,magnum, isthmus and shell gland) and theweakest level was found in the isthmus. The expression of the short isoform was lower than the long formin all examined tissue samples and no differences between oviductal parts were observed. Immunostaining specific for leptin receptor was found in the walls of all examined oviductal parts. The intensity of the immunopositive reaction was the strongest in the epithelium of all examined parts of the oviduct and in the endothelium and muscles of blood vessels. The weakest immunopositive reaction was observed in tubular glands, the connective tissue layer and in circular and longitudinal muscles. The results obtained in this experiment suggest that the oviductmay be a target tissue for leptin,where this polypeptide hormonmay participate in egg formation and/or its transport through the oviduct of the domestic hen.
The aim of the present investigation was to study peroxidase activity in different subcellular fractions of thyroid and oviduct and to ascertain whether there is any difference between the two sexes of peroxidase activity of the thyroid gland or between the thyroid and oviduct of a wild avian species, the tree pie (Dendrocitta vagabunda). Peroxidase activity was maximum in the soluble supernatant fraction of both the tissues with acetate buffer at pH 5.5, but the enzyme activity was highest even in low concentration of the substrate (H2O2) in the thyroid gland. Thiourea, thiouracil and azide inhibited enzyme activity in both thyroid and oviduct. While ascorbic acid inhibited peroxidase activity in the thyroid gland, it stimulated in the oviduct. Moreover, the enzyme activity was maximally inhibited by ascorbic acid in the thyroid and by thiourea in the oviduct. Peroxidase activity was highest with NAD+ in the thyroid and cytochrome C in the oviduct. Peroxidase activity was higher in females. It is suggested that avian thyroid/oviduct peroxidase activity may differ somewhat from that of mammals and possibly also in the peroxidase activity between the thyroid and oviduct of the tree pie.
The purpose of the present study was: (1) to demonstrate immunocytochemically the localization of histamine in the wall of four chicken oviductal parts, i. e. infundibulum, magnum, isthmus, and shell gland, (2) to identify the presence of mast cells in chicken oviduct, and (3) to determine histamine concentration in oviductal tissue by the spectrofluorometric method. Experiments were carried out on Isa Brown laying hens decapitated just after oviposition. The specific immuno-reactivity for histamine and the presence of mast cells were found in the wall of all the examined oviductal parts. The immuno-reactive histamine was localized in epithelium, tubular glands, connective tissue layer, circular and longitudinal muscles, and endothelium and muscles of blood vessels. The intensity of immuno-positive reaction was as follows: infundibulum > shell gland > magnum = isthmus and correlated with quantitatively determined histamine level and tissue density of mast cells. It is suggested that mast cells are the main source of histamine in the chicken oviduct.
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