The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
K. Muralidhar - One of the best experts on this subject based on the ideXlab platform.
-
mode of action of inhibin like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of Pineal Research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
-
Mode of action of inhibin‐like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of pineal research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
S. Duraiswami - One of the best experts on this subject based on the ideXlab platform.
-
mode of action of inhibin like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of Pineal Research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
-
Mode of action of inhibin‐like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of pineal research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
-
Inhibin‐like “antigonadotropic” activity in the ovine pineal
Journal of pineal research, 1992Co-Authors: Lakshmi Bhagat, S. DuraiswamiAbstract:In an attempt to define the antigonadotropic activity associated with the protein/peptide extracts of ovine pineals, melatonin- and steroid-free fractions obtained after subjecting crude ovine pineal acetone powder to soft gel chromatography were tested in three bioassay systems: (1) the conventional compensatory ovarian hypertrophy inhibition assay in rats, (2) the coupled bioassay in immature mice that enables one to distinguish factors acting at the level of the pituitary from those acting at the gonadal level, and (3) the classical in vitro pituitary cell culture assay for inhibin. The large molecular weight fraction, referred to as PI, behaved like a classical Antigonadotropin as it suppressed compensatory ovarian hypertrophy following unilateral ovariectomy. Further, it not only lowered the basal and gonadotropin releasing hormone (GnRH)-stimulated release of follicle stimulating hormone (FSH) by the cultured pituitary cells, but also inhibited the human chorionic gonadotropin (hCG)-induced uterine weight gain in the coupled assay, thus acting like inhibin in these two assay systems. In addition, it showed immunological cross-reactivity with ovine testicular inhibin. The present results strongly support the view that inhibin-like activity may be the major player in what has so far been referred to as antigonadotropic activity.
Eli Y Adashi - One of the best experts on this subject based on the ideXlab platform.
-
Rat Ovarian Insulin-Like Growth Factor Binding Protein-4: A Hormone-Dependent Granulosa Cell-Derived Antigonadotropin
The Journal of the Society for Gynecologic Investigation: JSGI, 1997Co-Authors: Lechoslaw Putowski, Richard M. Rohan, Doo Seok Choi, Wendy J. Scherzer, Elisabetta Ricciarelli, John Mordacq, Kelly E. Mayo, Eli Y AdashiAbstract:OBJECTIVE TO assess the in vivo regulation of ovarian insulin-like growth factor binding protein-4 (IGFBP-4) mRNA expression by gonadotropins and estrogen. METHODS Whole ovarian RNA, obtained from two models of follicular development, was extracted and analyzed by Northern blotting. Immature rats were treated with pregnant mare serum gonadotropin (PMSC) followed 48 hours later with hCG, or alternatively were hypophyseciomized and treated with FSH and/or diethylstilbestrol (DES). Localization ojTGFBP-4 expression was assessed in the former study by in situ hybridization. Finally, the ability of human IGFBP-4 to antagonize FSH-stimulated progesterone accumulation was assessed in vitro. RESULTS The ovarian content of IGFBP-4 transcripis increased threefold (P
-
Rat ovarian insulin-like growth factor binding protein-4: a hormone-dependent granulosa cell-derived Antigonadotropin.
Journal of the Society for Gynecologic Investigation, 1997Co-Authors: Lechoslaw Putowski, Richard M. Rohan, Doo Seok Choi, Wendy J. Scherzer, Elisabetta Ricciarelli, John Mordacq, Kelly E. Mayo, Eli Y AdashiAbstract:OBJECTIVE To assess the in vivo regulation of ovarian insulin-like growth factor binding protein-4 (IGFBP-4) mRNA expression by gonadotropins and estrogen. METHODS Whole ovarian RNA, obtained from two models of follicular development, was extracted and analyzed by Northern blotting. Immature rats were treated with pregnant more serum gonadotropin (PMSG) followed 48 hours later with hCG, or alternatively were hypophysectomized and treated with FSH and/or diethylstilbestrol (DES). Localization of IGFBP-4 expression was assessed in the former study by in situ hybridization. Finally, the ability of human IGFBP-4 to antagonize FSH-stimulated progesterone accumulation was assessed in vitro. RESULTS The ovarian content of IGFBP-4 transcripts increased threefold (P < .05) at 12 hours after PMSG but was near baseline at 24 and 48 hours. The abundance of IGFBP-4 mRNA increased (P < .05) again at 6 and 24 hours after hCG. The expression of IGFBP-4 was localized to granulosa cells of preantral (untreated) and small antral (12 hours after PMSG) follicles. No IGFBP-4 expression was noted in large (gonadotropin-primed) antral follicles. Hypophysectomy increased (P < .05) the ovarian content of IGFBP-4 mRNA by 1.5-fold, an effect further enhanced (1.8-fold; P < .05) by the provision of FSH and DES. In vitro studies revealed the ability of increasing concentrations (0.01-1 microgram/mL) of recombinant human IGFBP-4 to inhibit the FSH-supported accumulation of progesterone. CONCLUSION Increased expression after administration of PMSG, hCG, and FSH/DES suggests that IGFBP-4 is a dynamic and hormonally responsive component of the ovarian cycle. The lack of expression in preovulatory follicles and its antigonadotropic actions in vitro imply that the attenuated expression of IGFBP-4 may constitute a requirement for successful follicular maturation.
-
In Vivo Hormonal Regulation of Insulin-Like Growth Factor Binding Protein-5 mRNA in the Immature Rat Ovary
The Journal of the Society for Gynecologic Investigation: JSGI, 1995Co-Authors: Lechoslaw Putowski, Eli Y Adashi, Doo Seok Choi, Wendy J. Scherzer, John Mordacq, Kelly E. Mayo, Richard M. RohanAbstract:Objective Despite the potential importance of insulin-like growth factor binding protein-5 (IGFBP-5) to follicular development, the hormonal regulation of tfris antgonadotropic IGFBP has not been investigated. Therefore, it was the objective of this study to eludicate the role of gonadotropins and estrogen in the in vivo regulation of IGFBP-5 mRNA expression. Methods Two models of follicular development in immature rats were used. Specifically, rats were hypophysectomized and treated with FSH and/or diethylstilbestrol (DES). Alternatively, terminal follicular development was induced in intact immature rats by pregnant mare serum gonadotropin (PMSG) and hCG. The IGFBP-5 mRNA in whole ovarian RNA was assayed by Northern blot hybridization. Localization of expression in PMSG mid HCG-stimulated (ovaries was further assessed by in situ hybridization. Results Expression of IGFBP-5 mRNA was increased in ovaries from hypophysectomized rats. Treatmet with FSH and/or DES did not alter the abundance of this mRNA. Treatment with PMSG induced a transient increase in IGFBP-5 expression that was localized in a subset of α-inhibin-negative follicles. At later times after PMSG, IGFBP-5 expression persisted in the surface epithelium but was not detected in large preovulatory follicles. In vitro studies affirmed the antigonadotropic action of IGFBP-5. Conclusion In vivo expression oj IGFBP-5 in the rat ovary is moderated by hormonal treatment both in terms of total expression and follicular localization.
-
insulin like growth factor igf binding protein 1 is an Antigonadotropin evidence that optimal follicle stimulating hormone action in ovarian granulosa cells is contingent upon amplification by endogenously derived igfs
Advances in Experimental Medicine and Biology, 1994Co-Authors: Eli Y Adashi, Carol E Resnick, Ron G Rosenfeld, David R Powell, Riitta Koistinen, Eevamarja Rutanen, Markku SeppalaAbstract:Implicit in the antigonadotropic property of IGFBPs is the presumption that they sequester endogenously-generated IGFs thereby diminishing their access to cognate cell surface receptors and hence their cellular hormonal action. This communication examines this concept and the relevance of endogenous IGF to FSH action.
-
Granulosa cell-derived insulin-like growth factor (IGF) binding proteins are inhibitory to IGF-I hormonal action. Evidence derived from the use of a truncated IGF-I analogue.
The Journal of clinical investigation, 1992Co-Authors: Eli Y Adashi, Carol E Resnick, Ron G Rosenfeld, Elisabetta Ricciarelli, Eleuterio R. Hernandez, C Tedeschi, Luis Botero, Ehud Kokia, Arye Hurwitz, C Carlsson-skwirutAbstract:An increasing body of information now suggests that insulin-like growth factor (IGF) binding proteins (BPs) may serve as Antigonadotropins at the level of the ovary. It is the objective of the present communication to evaluate the functional role of endogenous (granulosa cell-derived) IGFBPs by exploiting the unique properties of des(1-3)IGF-I, a naturally occurring IGF-I analogue characterized as a weak ligand of IGFBPs but not of type I IGF receptors. Given IGFBP-replete circumstances, des(1-3)IGF-I proved more potent (10-fold) than its intact counterpart in promoting the follicle stimulating hormone (FSH)-stimulated accumulation of progesterone by cultured rat granulosa cells. In contrast, des(1-3)IGF-I proved virtually equipotent to the unmodified principle under IGFBP-deplete circumstances. Taken together, these findings are in keeping with the notion and that the apparently enhanced potency of des(1-3)IGF-I (under IGFBP-replete conditions) is due to its diminished affinity for endogenously generated IGFBPs and that rat granulosa cell-derived IGFBPs are inhibitory to IGF (and thus inevitably to gonadotropin) hormonal action. Accordingly, the reported ability of gonadotropins to attenuate IGFBP release by granulosa cells may be designed to enhance the bioavailability of endogenously generated IGFs in the best interest of ovarian steroidogenesis.
Lakshmi Bhagat - One of the best experts on this subject based on the ideXlab platform.
-
mode of action of inhibin like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of Pineal Research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
-
Mode of action of inhibin‐like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy
Journal of pineal research, 1994Co-Authors: Lakshmi Bhagat, S. Duraiswami, K. MuralidharAbstract:Bhagat L, Duraiswami S, Muralidhar K. Mode of action of inhibin-like pineal Antigonadotropin is different from melatonin during compensatory ovarian hypertrophy. J. Pineal Res. 1994:16:193–197. Abstract Both melatonin and pineal antigonadotropic peptides have the same end effect, i. e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal Antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemiovariec-tomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.
-
Inhibin‐like “antigonadotropic” activity in the ovine pineal
Journal of pineal research, 1992Co-Authors: Lakshmi Bhagat, S. DuraiswamiAbstract:In an attempt to define the antigonadotropic activity associated with the protein/peptide extracts of ovine pineals, melatonin- and steroid-free fractions obtained after subjecting crude ovine pineal acetone powder to soft gel chromatography were tested in three bioassay systems: (1) the conventional compensatory ovarian hypertrophy inhibition assay in rats, (2) the coupled bioassay in immature mice that enables one to distinguish factors acting at the level of the pituitary from those acting at the gonadal level, and (3) the classical in vitro pituitary cell culture assay for inhibin. The large molecular weight fraction, referred to as PI, behaved like a classical Antigonadotropin as it suppressed compensatory ovarian hypertrophy following unilateral ovariectomy. Further, it not only lowered the basal and gonadotropin releasing hormone (GnRH)-stimulated release of follicle stimulating hormone (FSH) by the cultured pituitary cells, but also inhibited the human chorionic gonadotropin (hCG)-induced uterine weight gain in the coupled assay, thus acting like inhibin in these two assay systems. In addition, it showed immunological cross-reactivity with ovine testicular inhibin. The present results strongly support the view that inhibin-like activity may be the major player in what has so far been referred to as antigonadotropic activity.
Fathalla Belal - One of the best experts on this subject based on the ideXlab platform.
-
Voltammetric study of danazol and its determination in capsules and spiked biological fluids.
Journal of pharmaceutical and biomedical analysis, 2005Co-Authors: Mohamed A. Al-omar, A. Al-majed, M. Sultan, Elrasheed A. Gadkariem, Fathalla BelalAbstract:Abstract The voltammetric behaviour of danazol DZ (Antigonadotropin) was studied using cyclic voltammetry, direct current, differential pulse polarography (DPP) and alternating current polarography. Danazol exhibited irreversible cathodic waves over the pH range of 1–5 in Britton Robinson buffers. At pH 1 (the analytical pH), a well-defined wave with E1/2 of −1.04 V versus Ag/AgCl reference electrode was obtained. The diffusion current constant ( I d ) was 4.8 ± 0.14 μA.L.m mole −1 and the current–concentration plot was rectilinear over the range from 5 × 10 −6 to 1 × 10 −4 M with correlation coefficient ( n = 11) of 0.995. The calculated detection limit was 1 × 10 −6 M using the DPP mode. The wave was characterized as being irreversible, diffusion-controlled although adsorption phenomenon played a limited role in the electrode process. The proposed method was applied to commercial capsules and the average percentage recovery was in agreement with that obtained by the official USP method. The method was extended to the in vitro determination of DZ in spiked human urine and plasma samples, the percentage recoveries were 96 ± 4 and 97 ± 5, respectively. A proposal of the electrode reaction was postulated.
-
Short communication Voltammetric study of danazol and its determination in capsules and spiked biological fluids
2005Co-Authors: M. Al-omar, A. Al-majed, M. Sultan, Fathalla BelalAbstract:The voltammetric behaviour of danazol DZ (Antigonadotropin) was studied using cyclic voltammetry, direct current, differential pulse polarography (DPP) and alternating current polarography. Danazol exhibited irreversible cathodic waves over the pH range of 1–5 in Britton Robinson buffers. At pH 1 (the analytical pH), a well-defined wave with E1/2 of −1.04 V versus Ag/AgCl reference electrode was obtained. The diffusion current constant (Id) was 4.8 ± 0.14A.L.m mole −1 and the current–concentration plot was rectilinear over the range from 5 × 10 −6 to 1 × 10 −4 M with correlation coefficient ( n = 11) of 0.995. The calculated detection limit was 1 × 10 −6 M using the DPP mode. The wave was characterized as being irreversible, diffusion-controlled although adsorption phenomenon played a limited role in the electrode process. The proposed method was applied to commercial capsules and the average percentage recovery was in agreement with that obtained by the official USP method. The method was extended to the in vitro determination of DZ in spiked human urine and plasma samples, the percentage recoveries were 96 ± 4 and 97 ± 5, respectively. A proposal of the electrode reaction was postulated. © 2004 Elsevier B.V. All rights reserved.