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ABSTRACT: The present study was performed to elucidate whether the angiotensin II (ANG II) receptor exists in the plasma membrane fraction of the neurohypophysis in hens, to estimate the time of action of ANG II on the neurohypophysis before and after oviposition, and to examine relationships between the action of ANG II on the neurohypophysis and those of estrogen and prostaglandin F(2α) (PGF(2α)) in relation to arginine vasotocin (AVT) release. The specific binding had a binding specificity to chicken ANG II (cANG II), reversibility, and saturation in the [(125)I]cANG II binding assay. Scatchard analysis revealed that the binding sites are of a single class. The equilibrium dissociation constant (K(d)) obtained by kinetic analysis and Scatchard analysis suggested a high affinity, and the maximum binding capacity (B(max)) obtained by Scatchard analysis suggested a limited capacity. These results suggest that an ANG II receptor exists in the neurohypophysis of hens. The K(d) and the B(max) value was significantly smaller in laying hens than in nonlaying hens, which suggests that bindings of the cANG II receptor change, depending on the difference in laying condition. Values of the K(d) and the B(max) decreased approximately 15 min before oviposition in laying hens, and decreased 1 h after an intramuscular injection of estradiol-17β and 5 min after an intravenous injection of cANG II in nonlaying hens. The amount of specific binding of PGF(2α) receptor in the neurohypophysis also decreased and AVT concentration in blood increased after the cANG II injection. It seems likely that the action of cANG II in the neurohypophysis increases due to the effect of estrogen approximately 15 min before oviposition, and the cANG II action stimulates AVT release through the increase in the PGF(2α) action in this tissue.
Poultry Science 11/2011; 90(11):2565-72. · 1.73 Impact Factor
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ABSTRACT: The specific binding component for prostaglandin F(2α) (PGF(2α)) that exists in the plasma membrane fraction of the oviduct uterus myometrium of laying hens was shown to possess receptor properties for PGF(2α), such as binding specificity to PGF(2α), binding saturation, high affinity, and limited capacity. The value of the equilibrium dissociation constant (K(d)) for the receptor was not different between laying hens and nonlaying hens, but the value of the maximum binding capacity (B(max)) was smaller in laying hens than in nonlaying hens. During an oviposition cycle, the K(d) value did not show a significant change, but the B(max) value decreased at 3 and 0.5 h before oviposition and 2 h after oviposition. Neither the K(d) nor B(max) value changed in nonlaying hens during a 24-h period. An intravenous injection of PGF(2α) (5 μg/hen) decreased the B(max) value, but not the K(d) value, of the PGF(2α) receptor. It is thought from the results that PGF(2α) may act directly on the oviduct uterus myometrium at a fixed time before and after oviposition in laying hens.
Poultry Science 08/2011; 90(8):1767-73. · 1.73 Impact Factor
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ABSTRACT: To demonstrate the presence of a receptor for calcitonin (CT) in the hen hypothalamus and to determine when CT acts on this tissue during the oviposition cycle, bindings of (125)I labeled CT in the plasma membrane fraction of the hen hypothalamus were measured by radioligand binding assay. The specific CT binding component in the plasma membrane fraction of the hypothalamus containing the preoptic area (HPOA) possessed properties of a receptor: binding specificity to CT, saturable binding, high affinity, and limited capacity. As for the median eminence area, no specific binding component was found in the present study. Therefore, the binding component for CT in the plasma membrane fraction of HPOA is likely to be a receptor for CT. In laying hens, the binding affinity of CT receptor increased at 30 min before oviposition and the binding capacity was decreased at 30 min before oviposition but not changed in nonlaying hens during a 24-h period. These results suggest that the action of CT on the hen HPOA may increase 30 min before oviposition.
Poultry Science 03/2011; 90(3):642-7. · 1.73 Impact Factor
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ABSTRACT: The presence of the receptor for parathyroid hormone-related peptide (PTHrP) and the effect of PTHrP on adrenocorticotropic hormone (ACTH) secretion in the hen anterior pituitary were examined. The plasma membrane fraction of the anterior pituitary was found to contain a specific chicken PTHrP (cPTHrP) binding component. The binding component had properties of a receptor, such as binding specificity to cPTHrP, reversibility, saturable binding, high affinity, and limited capacity; therefore, it was elucidated that the PTHrP receptor exists in the plasma membrane of the hen anterior pituitary. A third ventricular injection of cPTHrP in nonlaying hens caused a decrease in the chicken ACTH level of the anterior pituitary and an increase in the chicken ACTH level of blood plasma, with an increase in the binding affinity and a decrease in the binding capacity of PTHrP receptor in the anterior pituitary. The present study suggests that PTHrP may act directly on the anterior pituitary via its receptor binding and may enhance ACTH secretion from this tissue in hens.
Poultry Science 01/2011; 90(1):175-80. · 1.73 Impact Factor
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ABSTRACT: The present study was performed to elucidate whether estradiol-17β (E₂) would affect calcitonin (CT) receptor binding in the hen neurohypophysis. The equilibrium dissociation constant (K(d)) and the maximum binding capacity (B(max)) of the CT receptor in the plasma membrane fraction of the hen neurohypophysis were examined by Scatchard analysis of specific binding of (125)I-labeled chicken CT. A single i.m. injection of E₂ into nonlaying hens caused a decrease in K(d) and B(max) values of the CT receptor. The K(d) and B(max) values of the CT receptor were smaller in laying hens than in nonlaying hens. The present study suggests that E₂ may increase the action of CT on the neurohypophysis in hens.
Poultry Science 01/2011; 90(1):191-4. · 1.73 Impact Factor
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ABSTRACT: To demonstrate the presence of a receptor for calcitonin (CT) in the hen neurohypophysis and to estimate the time of action of CT on the neurohypophysis during the oviposition cycle in relation to arginine vasotocin (AVT) release, binding of (125)I-labeled chicken CT in plasma membrane fractions of the hen neurohypophysis was measured by the use of a radioligand binding assay. The binding specificity, reversibility, high affinity, and limited capacity are characteristics of a CT receptor. Therefore, it was elucidated that the CT receptor might exist in the plasma membrane of the neurohypophysis of hens. The binding affinity of CT receptor increased at 30 min before oviposition and the binding capacity was decreased at 15 min before oviposition. However, no change was found in non-laying hens during a 24-h period. Such changes in the CT receptor binding were found at 10 min after an i.v. injection of chicken CT into non-laying hens with an increase in the blood level of AVT. The changes in the binding affinity and capacity of CT receptor of the neurohypophysis may be related to AVT release partly at oviposition time in the hen.
Poultry Science 07/2010; 89(7):1473-80. · 1.73 Impact Factor
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ABSTRACT: The present study was performed to elucidate whether the receptor for calcitonin (CT) exists in the adrenocortical cells of hens and to determine the effect of CT on adrenocorticotropic hormone (ACTH)-stimulated corticosterone production in its cell. The binding site of CT in the membrane fraction of the adrenal gland in hens was determined using a [125I]CT binding assay system. The binding properties in the adrenal gland satisfied the criteria of a receptor-ligand interaction in terms of specificity, reversibility, and saturation. When the cortical cells were incubated in vitro with chicken ACTH in the presence of CT, greater corticosterone production was observed. The result suggested that CT acts directly on the adrenocortical cells via its receptor binding and increases responsiveness of ACTH on corticosterone production in the laying hen.
Poultry Science 10/2009; 88(10):2199-205. · 1.73 Impact Factor
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ABSTRACT: The present study was performed to elucidate whether the estrogen binding component regarded as a receptor exists in the plasma membrane fraction of neurohypophysis in hens and whether the binding of receptor changes with relation to oviposition. The specific binding for estradiol-17beta (E2) in the neurohypophysis of hens was demonstrated by the use of radioligand binding assays on the plasma membrane fraction of the tissue. The binding to [3H]E2 had a binding specificity to E2 and diethylstilbestrol, reversibility, and saturation. Scatchard analysis revealed that the binding sites are of a single class. The equilibrium dissociation constant obtained by Scatchard analysis and kinetic analysis suggested a high affinity, and the maximum binding capacity obtained by Scatchard analysis suggested a limited capacity. These properties are characteristics of a receptor, which suggests that an estrogen receptor exists in the plasma membrane of hen neurohypophysis. The equilibrium dissociation constant value of estrogen receptor of the neurohypophysis was not significantly different between laying hens and nonlaying hens, but the maximum binding capacity value was statistically smaller (the binding affinity is higher) in laying hens than in nonlaying hens. The specific binding of estrogen receptor showed a decrease at 1 h after an injection of diethylstilbestrol in nonlaying hens. The specific binding also decreased 3 h before oviposition in laying hens and maintained low value until just after oviposition. The present study suggests that estrogen may act directly on the neurohypophysis during 3 h before oviposition in hens.
Poultry Science 10/2009; 88(10):2206-11. · 1.73 Impact Factor
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ABSTRACT: To elucidate whether the receptor for prostaglandin (PG) F(2alpha), one of PG, exists in the neurohypophysis in hens and whether the binding of receptor changes with relation to oviposition, the PGF(2alpha) binding component in the membrane fraction of the neurohypophysis of laying hens was analyzed by radioligand binding assay using [5,6,8,9,11,12,14,15(n)-(3)H]PGF(2alpha). The binding component had characteristics of a receptor such as binding specificity, high affinity, and limited capacity for PGF(2alpha). Scatchard analysis indicated that the binding site was of a single class. The binding capacity of the receptor was smaller in laying hens than in nonlaying hens, whereas the binding affinity was not significantly different between these hens. When non-laying hens received an i.m. injection of estradiol-17beta or progesterone (0.5 mg/hen), the specific binding of the PGF(2alpha) receptor in the neurohypophysis was decreased. In laying hens, the specific binding decreased and the blood arginine vasotocin (AVT) concentration increased just after oviposition but did not change during a 24-h day in nonlaying hens. An i.v. injection of PGF(2alpha) (2 microg/hen) induced oviposition and caused an increase in the blood AVT concentration with a decrease in the specific binding of PGF(2alpha) receptor. The present study suggests a possibility that PGF(2alpha) may directly cause the AVT release from the neurohypophysis at oviposition time in hens.
Poultry Science 09/2009; 88(8):1712-8. · 1.73 Impact Factor
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ABSTRACT: The present study was performed to elucidate whether mesotocin (MT), one of avian neurohypophysial hormones, relates to the action of arginine vasotocin (AVT) on oviposition of hens. The ratio of AVT-induced oviposition was increased when 1 microg/hen of MT was injected together with AVT. An intravenous injection of 1 microg/hen of MT caused an increase in the binding affinity of the uterine AVT receptor and a decrease in the binding capacity. Blood MT concentrations measured by RIA increased approximately 1 min before oviposition during the period of the bearing-down behavior, but the AVT concentration did not change at this time. The blood AVT concentration dramatically increased within 1 min just after oviposition. The results suggest that MT may have an effect of enhancing the inducing oviposition by AVT through the increase in the sensitivity of the uterus to AVT at oviposition in hens.
Poultry Science 11/2008; 87(10):2107-11. · 1.73 Impact Factor
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ABSTRACT: [(125)I]mesotocin (MT) binding of membrane fractions of the oviduct uterus in laying hens and nonlaying hens was measured by the use of radioligand binding assay to elucidate the presence of MT receptor in the uterine tissue, and whether the binding to the receptor changes before and after oviposition. The uterine tissue of the hen was found to contain a specific [(125)I]MT binding component having properties of MT receptor (i.e., binding specificity, saturable binding, high affinity, and limited capacity). The equilibrium dissociation constant (K(d)) was 0.46 +/- 0.05 nM (x +/- SEM; n = 4) in laying hens holding a hard-shelled egg in the uterus (shell gland) and 0.78 +/- 0.02 nM (n = 4) in nonlaying hens. The maximum binding capacity (B(max)) was 0.28 +/- 0.03 pmol/mg of protein (n = 4) in laying hens and 0.19 +/- 0.01 pmol/mg of protein (n = 4) in nonlaying hens. The K(d) value of the laying hens varied from 0.37 to 0.91 nM during an oviposition cycle showing a decrease 30 min before oviposition and an increase 4 h after oviposition. The B(max) value also varied from 0.15 to 0.38 pmol/mg of protein showing an increase 3 h before oviposition, a decrease 30 min before oviposition, and an increase 4 h after oviposition. In the nonlaying hen, both values were almost constant during a 24-h day. The changes in the binding affinity and capacity of MT receptor of the uterus may be related to oviposition in the hen.
Poultry Science 04/2008; 87(3):546-50. · 1.73 Impact Factor
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ABSTRACT: The presence of receptor for chicken parathyroid hormone-related peptide (cPTHrP) in the cortical cells of the adrenal gland of the hen was demonstrated by radioligand binding assays. When the cortical cells were incubated in vitro with chicken adrenocorticotropic hormone (cACTH) in the presence of cPTHrP, greater production of corticosterone was observed than when incubated with cACTH alone. The results suggest that PTHrP may act directly on the adrenocortical cells via its receptor binding and increase the response to ACTH for corticosterone secretion in the hen.
Poultry Science 10/2005; 84(9):1463-9. · 1.73 Impact Factor
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ABSTRACT: The prostaglandin F (PGF) concentration of the uterus (shell gland) of the hen oviduct, measured by a radioimmunoassay, was found to increase slightly 6 h before oviposition and steeply immediately after oviposition. An intravenous injection of arginine vasotocin (AVT) caused the increase in the uterine PGF concentration and induced oviposition. When indomethacin was injected before the injection of AVT, the uterine PGF concentration was not increased, and the incidence of oviposition was reduced. Estrogen injection caused an increase in the uterine PGF concentration at 1 and 2 h after injection. Specific binding of the estrogen receptor of the uterine tissue increased 9 and 7 h before oviposition. The slight increase in the uterine PGF concentration 6 h before oviposition may be due to the action of estrogen via its receptor, and the steep increase immediately after oviposition may be caused by AVT released at the time of oviposition.
Poultry Science 10/2004; 83(10):1745-9. · 1.73 Impact Factor
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ABSTRACT: An intravenous injection of arginine vasotocin (AVT) at 16 h before the expected oviposition of the initial egg of an egg-laying sequence caused bearing down for oviposition. Oviposition was increased up to 100% by increasing the dose of AVT up to 1 microg, but it decreased when the dose was 10 and 20 microg. Bearing down was observed even when the oviposition was not induced by the injection of a higher dose of AVT. The results of the present experiment suggest that bearing down is not necessarily caused by the entering of egg into the vagina, but instead may be caused by hormonal stimulus of AVT receptors present in vaginal tissue.
Poultry Science 03/2003; 82(2):345-6. · 1.73 Impact Factor
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ABSTRACT: The equilibrium dissociation constant (Kd) and the maximum binding capacity (Bmax) of receptors for parathyroid hormone (PTH)/parathyroid hormone-related peptide (PTHrP) and calcitonin (CT) in the membrane fraction of the calvaria and the kidney of chickens were examined from 1 d after the hatch up to 24 wk of age by the use of radioligand binding assays. The Kd values of the PTH/PTHrP receptor in both tissues were decreased at 10 and 24 wk in female birds, whereas the values were increased at 24 wk in male birds. The Bmax values of the PTH/PTHrP receptor in both tissues were decreased at 10 wk and returned to baseline at 24 wk in female birds. The values were increased at 24 wk in male birds. The Kd and Bmax values of CT receptors in the both tissues were constant during the experimental period in female and male birds. The results suggest that the binding properties of PTH/PTHrP receptor and of CT receptor may be influenced by gonadal hormones relating to sexual maturation.
Poultry Science 09/2001; 80(8):1231-5. · 1.73 Impact Factor
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ABSTRACT: Parathyroid hormone (PTH) receptor binding property in the membrane fraction of the endometrium of the shell gland (uterus) of the guineafowl was analyzed by the use of [125I]PTH-related peptide (PTHrP) binding assays. Specificity, reversibility, and saturation of binding were demonstrated. Scatchard plots revealed a single class of binding sites. The equilibrium dissociation constant (Kd) was 0.50 to 1.15 nM in laying birds and 1.07 to 1.16 nM in nonlaying birds. The maximum binding capacity (Bmax) per milligram of membrane protein was 65.2 to 110.9 femtomoles (fmol) in laying birds and 105.8 to 120.6 fmol in nonlaying birds. Both Kd and Bmax values changed within the above range during an oviposition cycle in laying birds, showing a decrease during the period of eggshell formation. No change was found in nonlaying birds. The results suggest that PTH/PTHrP receptors are present in the shell gland of the guineafowl, and their binding may be related to eggshell formation.
Poultry Science 05/2000; 79(4):575-9. · 1.73 Impact Factor
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ABSTRACT: In this study, parathyroid hormone (PTH) receptor binding was examined in the membrane fraction of the endometrium of the shell gland of laying and nonlaying hens by the use of (125)I-PTH-related peptide (PTHrP) binding assays. Specific (125)I-PTHrP binding was found in the endometrium of the shell gland and increased during the first 1 h of incubation and then reached a plateau. Specific (125)I-PTHrP binding increased in line with an increase in protein concentration from 10 to 80 microg. The membrane fraction had specific binding to (125)I-PTHrP. The Scatchard plot analysis revealed a linear profile that indicated the presence of one type of receptor. The equilibrium dissociation constant (K(d)) and the maximum binding capacity (B(max)) in the shell gland decreased 19 h before oviposition in egg-laying hens and remained low for about 20 h during the period of calcification. In contrast, the K(d) and the B(max) in nonlaying hens were constant throughout a 24-h period. These results suggest that PTH acts on the endometrium of the shell gland during the eggshell calcification.
General and Comparative Endocrinology 03/2000; 117(2):182-8. · 3.27 Impact Factor
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ABSTRACT: Prostaglandin F (PGF) concentrations in the serum of laying and nonlaying hens and of cocks at various times during a day were measured by radioimmunoassay. The serum concentration of PGF was higher in laying hens than in nonlaying hens or cocks without regard to time of day. In all birds, the concentration showed a peak at 2 h after onset of light (0700 h). In laying hens on the day of laying the fourth egg of a sequence, two peaks were found: one at 2 h after onset of light and another at the time immediately after oviposition. The results suggest that the serum concentration of PGF in both male and female chickens shows a daily change and that in laying hens it also shows a change associating with oviposition.
Poultry Science 07/1999; 78(6):906-8. · 1.73 Impact Factor
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ABSTRACT: Cytosolic and nuclear fractions of the uterus (shell gland) of the hen's oviduct were found to contain a specific [17alpha-methyl-3H]-methyltrienolone ([3H]R1881; a synthetic androgen) binding component having properties of an androgen receptor; i.e., binding specificity, high affinity, and limited capacity. The value of the equilibrium dissociation constant (Kd) was of the order of 10(-9), and did not differ between laying and nonlaying hens. The maximum binding capacity (Bmax) per gram of tissue of both fractions was greater in laying hens than in nonlaying hens. When 5alpha-dihydrotestosterone was administered exogenously, the Bmax of the cytosolic fraction decreased and that of the nuclear fraction increased without any change in Kd. The specific binding in both fractions was at an increased level from 4 to 11 h before oviposition, suggesting that androgen binding may be related to certain events during an early stage of shell formation in the uterus of laying hens.
Poultry Science 02/1999; 78(1):107-13. · 1.73 Impact Factor
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ABSTRACT: The presence of receptor for arginine vasotocin (AVT) in the vagina of the oviduct of the hen was demonstrated by the use of radioligand binding assays on membrane fractions of the tissue. The binding to [125I]AVT was highly competitive with unlabeled AVT. Scatchard analysis revealed that the binding sites are of a single class. The equilibrium dissociation constant (Kd) was 0.48+/-0.05 nM (x+/-SEM; n = 6) in laying hens holding a hard-shelled egg in the uterus (shell gland) and 1.01+/-0.02 nM (n = 6) in nonlaying hens. The maximum binding capacity (Bmax) was 0.41+/-0.04 pmol/mg protein (n = 6) in laying hens and 0.81+/-0.01 pmol/mg protein (n = 6) in nonlaying hens. The Kd value of the laying hens varied from 0.39 to 1.20 nM during an oviposition cycle, showing an increase just prior to oviposition, and the Bmax value also varied from 0.30 to 0.66 pmol/mg protein, showing a gradual increase after 6 h prior to oviposition. In the nonlaying hen, both values were almost constant during a 24-h day. The changes in the binding affinity and capacity of AVT receptor of the vagina may be related to oviposition in the hen.
Poultry Science 12/1998; 77(11):1699-703. · 1.73 Impact Factor
