Biomedical subjects

M Kamiyoshi

Publications and source records attributed to M Kamiyoshi.

At least 19 recordsLinked to original sources

PubMed2001

Expression of messenger RNA for gonadotropin receptor in the granulosa layer during the ovulatory cycle of hens.

The present experiments were conducted to evaluate the mRNA levels of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) in granulosa layers during the ovulatory cycle of hens, in relation to the release of LH and steroid hormones. After the release of LH, progesterone (P4) and estradiol-17beta (E2), found 4-5 h before ovulation, LHR and FSHR mRNA levels were observed to decrease in the granulosa layers of the largest (F1) and second largest (F2) preovulatory follicles, with the greatest in the LHR mRNA level of F1. P4 concentrations in the granulosa layers of F1 and F2 increased 4-5 h before ovulation, with greater in F1 than in F2. F2 concentrations in the theca layers were greater in F2 than in F1 throughout the ovulatory cycle. Also, the injection of ovine LH caused decreases in the mRNA levels of LHR and FSHR in the granulosa layers. However, these decreases were abolished by the injection of aminoglutethimide, an inhibitor of steroid synthesis. These results suggest that in hen granulosa cells, the mRNA levels of not only LHR but also FSHR are down-regulated by LH and the down-regulation may be mediated steroid hormones.

Aminoglutethimide↗

PubMed1998

Molecular cloning and functional expression of chicken luteinizing hormone receptor.

A complementary DNA for chicken luteinizing hormone (LH) receptor containing the entire coding region was isolated from chicken F1 granulosa cell cDNA library. Nucleotide sequence analysis revealed that there are characteristic GC-rich regions around the N-terminal part. Chicken LH receptor consists of a 19-residue signal peptide, a 366-residue extracellular domain, a 267-residue region containing seven transmembrane segments, and a 76-residue cytoplasmic C-terminal tail. The deduced amino acid sequence of the chicken LH receptor shares 67%, 69%, and 69% identity with the human, rat and porcine LH receptor sequences, respectively, and 51% with chicken FSH receptor. However, an insertion of about 30 amino acid residues is found in chicken LH receptor in the extracellular domain about 44 amino acid residues upstream of the first transmembrane segment. In addition, alternative splicing seems likely to occur at the point where the insertion starts (nucleotide position 933), resulting in the truncated forms of chicken LH receptor with only the extracellular domain. Northern blot analysis revealed the presence of multiple transcripts of LH receptor, a major 3.0-kb and minor 7-kb and 1.5-kb bands, in chicken F1 to F3 granulosa cells. The full length chicken LH receptor cDNA was transiently expressed in COS-7 cells and the transfected cells displayed a concentration-dependent increase in cAMP production when exposed to varying concentrations of chicken LH. This clearly indicates that the cloned cDNA encodes a functional chicken LH receptor protein.

Amino Acid Sequence↗

PubMed1998

Chicken lutropin acts like follitropin in rat ovarian follitropin receptor: an isoelectric focusing study.

This study investigates whether chicken lutropin (LH) specifically binds to rat ovarian follitropin (FSH) receptor and exerts FSH-like bioactivity. Glycoprotein fraction, prepared from the chicken anterior pituitary gland, was fractionated using isoelectric focusing within a pH range of 3.5-11. Analysis of the focused fractions, by a radioreceptor assay (RRA) specific for FSH in rats using rat ovarian homogenate as receptor source, and 125I-labeled rat FSH as radioligand, detected a large component having an isoelectric point of 10.25. This focusing profile obtained by RRA was quite similar to that obtained by a specific radioimmunoassay (RIA) for chicken LH, but clearly different from that obtained by a specific RIA for chicken FSH, indicating this RRA specifically recognizes chicken LH. Chicken LH fraction prepared from the electrofocused material was used for further studies. The chicken LH preparation was three times more potent than rat FSH in the RRA in displacing the radioligand bound to rat ovarian receptor, while chicken LH facilitated an 8-fold less production of estradiol in dispersed rat granulosa cells than rat FSH. These results suggest that chicken LH acts like rat FSH in rat ovarian FSH receptor, but receptor-binding activity is much higher than biological activity.

Animals↗

PubMed1998

Evaluation of a sensitive, in vitro bioassay for chicken thyroid stimulating hormone using FRTL-5 cells, a rat thyroid cell line.

An in vitro bioassay for mammalian thyroid stimulating hormone (TSH) based on TSH-induced cyclic adenosine 3',5'-monophosphate (cAMP) production in FRTL-5 cells, a rat thyroid cell line, was used to measure chicken TSH. The addition of chicken pituitary homogenate equivalent to > or = 25% of a chicken pituitary gland to cultured FRTL-5 cells increased cAMP within these cells in a dose-dependent manner. The glycoprotein fraction derived from the pituitary homogenate was further fractionated by isoelectric focusing within a pH range of 5 to 11. Analysis of the focused fractions by the bioassay detected three major components with isoelectric points of 9.30, 7.12, and 3.82, in addition to several minor ones distributed over a wide range of pH, from alkaline to acidic. The isoelectric focusing profile obtained by the bioassay was clearly different from those obtained by radioimmunoassay for chicken LH and radioreceptor assay for chicken FSH, indicating that fractions contained chicken TSH. The homogenate of the cephalic portion of the chicken anterior pituitary gland was 4.46 times more active than that of the caudal portion in the bioassay, which is consistent with previous findings on localization of TSH in the chicken pituitary. We conclude that the bioassay using FRTL-5 rat thyroid cells is a sensitive, specific, and time-saving method of measuring chicken TSH.

Analysis of Variance↗

PubMed1998

Complementary DNA sequence of chicken thyroid-stimulating hormone (TSH) beta subunit.

Chicken TSH beta subunit cDNA was cloned and sequenced. The cDNA encodes a putative signal peptide and a mature protein consisting of 20 and 114 amino acids, respectively. The amino acid sequence of chicken TSH beta subunit is highly conserved (98.5%) between chicken and Japanese quail, whereas it has a low homology between chicken and mammals (67-69%), an amphibian (58%) and fish (40-49%). Structural characteristics of TSH beta subunits of avian species are discussed in comparison with those of non-avian vertebrates.

Amino Acid Sequence↗

PubMed1997

Mesotocin receptor binding of cortical and medullary kidney tissues of the hen.

[125I]Mesotocin (MT) binding of membrane fractions of the cortical tissue and the medullary tissue (medullary cone) of the kidney of nonlaying hens was measured by the use of radioligand binding assays to determine the distribution of two distinct MT receptors within the hen kidney. The binding to [125I]MT in the medullary tissue was found to be highly competitive with unlabeled MT. In the cortical tissue, the binding was competitive with both unlabeled MT and arginine vasotocin. Kinetic and Scatchard analyses of specific binding revealed that the binding affinity was higher in the cortical tissue than in the medullary tissue, but the binding capacity was less in the cortical tissue. The localization of two distinct MT receptor having different binding properties may be related to the biphasic action of MT within the tissue of the kidney of the hen.

Animals↗

PubMed1996

Effects of progesterone, estrogen, and androgen on progesterone receptor binding in hen oviduct uterus (shell gland).

The specific [3H] progesterone binding per milligram of protein of the cytosolic fraction of the hen uterus was found to have decreased at 1 and 4 h after the injection of progesterone (P4), but increased at 4 and 8 h after the injection of estradiol-17 beta (E2), and at 1 and 4 h after the injection of testosterone (T). The equilibrium dissociation constant obtained by Scatchard analysis was not significantly different between the hens receiving steroid injections [P4], E2, T, and dihydrotestosterone (DHT)] and controls. The maximum binding capacity was lower in hens injected with P4 and greater in hens injected with E2, T, or DHT than in uninjected hens. The results suggest that the cytosolic progesterone receptor binding in the hen uterus may be modulated by the sex steroid hormones.

Analysis of Variance↗

PubMed1996

Mesotocin binding to receptors in hen kidney plasma membranes.

Radioligand assays were performed to demonstrate the presence of a receptor for mesotocin (MT) in the membrane fractions of the kidney of the hen. Specific [125I]MT bindings were decreased by the presence of Mg2+ and Ca2+, increased by the presence of EDTA, increased during the first 4 h of incubation and then reached a plateau, and increased with the increase in the protein concentration from 2.5 to 20 micrograms. The membrane fraction showed binding specificity to [125I]MT. The Scatchard plot revealed a curvilinear profile that indicated the presence of two classes of binding sites: a high affinity site and a low affinity site. The equilibrium dissociation constant was 0.08 +/- 0.01 nM (mean +/- SEM; n = 5) in the high affinity site and 0.87 +/- 0.08 nM (n = 5) in the low affinity site. The maximum binding capacity of the high and low affinity sites was 42 +/- 4 and 129 +/- 6 fmol/mg protein, respectively. The results suggest the presence of two distinct MT receptors in the kidney of the hen.

Animals↗

PubMed1995

Presence of vasoactive intestinal peptide receptor in the hen hypothalamus.

Radioligand assays of the membrane fraction of hen hypothalamic tissues involving the preoptic (HPOA) or median eminence (HMEA) areas revealed the presence of a specific binding component to chicken vasoactive intestinal peptide (cVIP) having properties of a receptor. The equilibrium dissociation constant (Kd) was 0.70 +/- 0.07 nM (Mean +/- SEM; N = 5) in HPOA and 1.02 +/- 0.15 nM (N = 5) in HMEA as estimated by Scatchard analysis of saturation studies, and was 0.91 +/- 0.11 nM (N = 3) (HPOA) and 1.25 +/- 0.09 nM (N = 3) (HMEA) as determined by a kinetic analysis. The maximum binding capacity (Bmax) obtained by Scatchard analysis was 167 +/- 19 fmol/mg protein (N = 5) (HPOA) and 133 +/- 17 fmol/mg protein (N = 5) (HMEA). The Kd and Bmax values obtained by Scatchard analysis were similar in the two areas of the hypothalamus and in both laying and nonlaying hens. Administration of cVIP in vivo caused a decrease in specific cVIP binding. These results suggest the presence of a VIP receptor in the hen hypothalamus.

Animals↗

PubMed1995

A vasoactive intestinal peptide binding component in hen granulosa cells.

In radioligand assays, the vasoactive intestinal peptide (VIP) binding component in the membrane fraction of granulosa cells of the ovary of the hen was shown to possess characteristic properties of a receptor, such as reversible binding, binding specificity, high-affinity, and limited capacity. The binding site was of a single class. The binding affinity was higher in the largest (F1) and the second largest follicle (F2) than in the third largest follicle (F3), and the binding capacity was greater in F2 and F3 than in F1. During the ovulatory cycle, changes in affinity and capacity were observed only in F1 shortly before ovulation. The results suggest the presence of VIP receptor in the hen granulosa cells and its binding is assumed to be related to the follicular growth and ovulation.

Animals↗

PubMed1995

An opiate receptor in the neurohypophysis of laying hens.

An opiate binding component in the membrane fraction of the neurohypophysis of the laying hen showed a high affinity, limited capacity, reversible binding, and binding specificity to [3H]diprenorphine. The binding sites were of a single class. The equilibrium dissociation constant was .30 +/- .03 nM (mean +/- SEM; n = 5) in Scatchard analysis and .31 +/- .02 nM (n = 5) in kinetic analysis. The maximum binding capacity determined by Scatchard analysis was 619 +/- 34 fmol/mg protein (n = 5). The association and dissociation rate constants determined by kinetic analysis were .088 +/- .002 nM-1 min-1 (n = 5) and .027 +/- .001 min-1 (n = 5), respectively. The results suggest that the binding component is regarded as being an opiate receptor.

Animals↗

PubMed1995

Diuretic and antidiuretic effects of mesotocin as compared with the antidiuretic effect of arginine vasotocin in the hen.

Mesotocin and arginine vasotocin were injected intravenously once at various dosage levels (.0025 to 25 micrograms/kg body weight) immediately after an intravenous injection of 15 mL/kg body weight saline solution into hens in which an artificial anus had been surgically created, and the volume of urine excreted during a 5-h period, following the injection, was measured. Arginine vasotocin caused a monophasic, dose-dependent decrease in urine volume. By contrast, mesotocin was biphasic: at .025 and .25 micrograms/kg body weight it decreased urine volume with the same efficacy as arginine vasotocin, whereas it dramatically increased urine volume at the higher doses (2.5 and 25 micrograms/kg body weight).

Animals↗

PubMed1994

Arginine vasotocin receptor binding in the hen uterus (shell gland) before and after oviposition.

The binding affinity and capacity of arginine vasotocin (AVT) receptor in the hen uterus changed during a period before and after oviposition. Three hours before oviposition, the binding capacity of the AVT receptor increased. An injection of prostaglandin (PG) F2 alpha caused an increase in the AVT receptor Bmax in the uterus, and indomethacin blocked the normal rise in the AVT receptor Bmax and PGF content prior to oviposition. However, just prior to oviposition, the binding affinity increased with a decrease in the binding capacity. A progesterone injection caused an increase in binding affinity and a decrease in binding capacity of the AVT receptor. The specific binding of the progesterone receptor in the uterus increased 2 h before oviposition and remained high until oviposition. Serum AVT levels increased at oviposition. An injection of AVT caused an increase in the affinity of the AVT receptor with a decrease in the capacity. The change in the affinity and capacity of AVT receptor at oviposition may result from the action of progesterone via increased progesterone receptor binding, and the action of AVT on its own receptors.

Animals↗

PubMed1994

Effect of estradiol-17 beta and progesterone on arginine vasotocin in nonlaying hens.

Effect of estradiol-17 beta (E2) and progesterone (P4) on serum arginine vasotocin (AVT) concentration was examined. Serum AVT concentration was lower in nonlaying hens than in laying hens. A single intramuscular injection of E2 or P4 into nonlaying hens caused an increase in serum AVT concentration, suggesting that estrogen and P4 may stimulate the release of AVT from the neurohypophysis.

Animals↗

PubMed1994

Changes in progesterone receptor binding of preoptic hypothalamus during an ovulatory cycle of the hen.

By the use of radioligand assays, cytosolic and nuclear fractions of hypothalamic tissue involving preoptic area (HPOA) of the hen was found to contain a specific [17 alpha-methyl-3H]promegestone ([3H]-R5020; a synthetic progesterone) binding component having properties of receptor for progesterone. The equilibrium dissociation constant (Kd) was different neither between cytosolic and nuclear fractions nor between the fractions of laying and nonlaying hens. The maximum binding capacity (Bmax) per milligram of tissue of both fractions was greater in laying hens than in nonlaying hens. During the ovulatory cycle of laying hens, the specific [3H]-R5020 binding in cytosolic fraction showed a decrease, with an increase in the nuclear fraction from 21 to 18 h and from 6 to 3 h before ovulation. Such a change was not observed in nonlaying hens during a 24-h day. The results suggest that progesterone receptors are present in the preoptic hypothalamus and may be related to the incidence of ovulation in the hen.

Animals↗

PubMed1993

Estrogen receptor binding in the hen hypothalamus and pituitary during the ovulatory cycle.

The equilibrium dissociation constant (Kd) and the maximum binding capacity (Bmax) of estrogen receptor in soluble (cytosolic) and insoluble (nuclear) fractions in a hypotonic buffer solution of hypothalamus containing preoptic (HPOA) and median eminence (HMEA) areas and of anterior pituitary (AP) of laying and nonlaying hens were examined by Scatchard analysis of specific [3H]estradiol-17 beta ([3H]-E2) binding. The Kd of receptor in all of the tissues was different neither between soluble and insoluble fractions, nor between laying and nonlaying hens. The Bmax in laying hens was greater in the insoluble fraction and lower in the soluble fraction than that in nonlaying hens, but the total binding capacity (sum of Bmax in the soluble and insoluble fractions) was not different between laying and nonlaying hens. In laying hens, the specific [3H]-E2 binding in the insoluble fraction of HPOA was found to increase at 21 h before ovulation and again at 8 to 6 h before ovulation, and of HMEA and AP at 18 to 11 h before ovulation. No change in the specific [3H]-E2 binding in the insoluble and soluble fractions was found in any of the tissues of nonlaying hens during a 24-h period. The results suggest that in laying hens, estrogen may act on the hypothalamus and pituitary at restricted hours during the ovulatory cycle.

Animals↗

PubMed1992

Arginine vasotocin binding component in the uterus (shell gland) of the chicken.

The plasma membrane fraction of the uterus of the chicken was found to contain a component that shows specific binding to arginine vasotocin (AVT), arginine vasopressin (AVP) and oxytocin (OT). This binding component possesses a higher affinity to AVT than to AVP or OT, and the affinity to AVT was higher in laying hens than in non-laying hens and immature pullets, while the maximum number of binding sites per mg protein was less in the laying hens. Intramuscular injections of either estradiol-17 beta, progesterone or testosterone into the immature pullets for six consecutive days caused an increase in the affinity and number of binding sites. The results suggest that AVT receptors are present in the chicken uterus and that their binding properties are affected by ovarian steroid hormones.

Animals↗

PubMed1992

Enhancement of progesterone receptor bindings by estradiol in pituitary cells of the hen.

Isolated cells from pituitaries of nonlaying hens were incubated in vitro with and without estradiol-17 beta (E2), and the amount of progesterone receptor binding in the cytosolic fraction of the cells was measured by an exchange assay. When the cells were incubated with 1.0 ng E2 for 1, 2, or 4 h, the progesterone receptor bindings were increased. The bindings were not increased when incubated together with cycloheximide, actinomycin-D, or alpha-amanitin. The results suggested that the cytosolic progesterone receptor binding of pituitary cells was enhanced by the action of estrogen through a protein-synthesizing pathway.

Animals↗