7 results on '"Padmanabhan, Vasantha"'
Search Results
2. 289 Postnatal Obesity Amplifies the Effect of Prenatal Testosterone Excess in Reducing the Progesterone Negative Feedback Sensitivity in First-Generation Ewes
- Author
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Gurule, Sara C, primary, Sustaita-Monroe, Jessica F, additional, King, Leslie, additional, Garza, Viviana, additional, West, Sarah, additional, Weynand, Morgan, additional, Ecord, Emily, additional, Padmanabhan, Vasantha, additional, and Cardoso, Rodolfo C, additional
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- 2023
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3. 295 Effects of Prenatal Testosterone Excess on Puberty Attainment of First-Generation ewe Lambs
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Gurule, Sara C, primary, Sustaita, Jessica F, additional, Landers, Renata, additional, King, Leslie, additional, Garza, Viviana, additional, Bynum, Sarah, additional, Arrott, Dylan, additional, Padmanabhan, Vasantha, additional, and Cardoso, Rodolfo C, additional
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- 2022
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4. Postnatal Obesity Amplifies Gnrh-Induced Lh Release in Prenatal Testosterone-Treated Female Sheep.
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Sustaita-Monroe, Jessica F., Gurule, Sara C., King, Leslie, West, Sarah, Garza, Viviana, Earnhardt-San, Audrey L., Welsh, Thomas H., Padmanabhan, Vasantha, and Cardoso, Rodolfo C.
- Subjects
SHEEP ,ENDOCRINE diseases ,POLYCYSTIC ovary syndrome ,CORN oil ,CHILDBEARING age ,LAMBS ,PRECOCIOUS puberty - Abstract
Polycystic ovary syndrome (PCOS) is the most common hormonal disorder in females of reproductive age. Hypersecretion of luteinizing hormone (LH), partly due to increased pituitary sensitivity to gonadotrophin-releasing hormone (GnRH), is a significant cause of infertility in women with PCOS. Moreover, obesity amplifies the severity of reproductive dysfunction in PCOS. In sheep, testosterone (T) excess during gestational days (GD) 30 to 90 results in GnRH-mediated LH hypersecretion and recapitulates the PCOS phenotype. This study investigated 1) if midgestation (GD 60 to 90) is the susceptibility window for programming pituitary hypersensitivity to GnRH, and 2) the contribution of postnatal obesity in modulating LH responsiveness to GnRH. Suffolk ewes received T propionate (T; 100 mg i.m.) or corn oil (C; vehicle) twice weekly from GD 60 to 90 (term = 147 d). At 5 mo of age, T lambs were assigned randomly to either a maintenance (100% of NRC requirements) or overfed diet (130% of NRC requirements), and Control lambs were fed the maintenance diet. During the anestrous period (late summer), ewes (n = 8/group; ~17 mo of age) received a GnRH bolus injection (2 ng/kg) intravenously every 1.5 h and blood samples were collected at 15-min intervals for a 6-h period. Despite animals being in seasonal anestrous, few endogenous LH pulses were evident during the 6 h-sampling period. To avoid confounding, only clear responses to GnRH challenge that occurred within 15 to 45 min after each GnRH injection were considered for further analyses. Mean number of exogenous GnRH-induced LH responses that met these criteria did not differ between groups and averaged 1.81 ± 0.27 pulses/animal. The parameters of these GnRH-induced responses were analyzed as one-way ANOVA with Tukey's HSD post-hoc analysis. Mean LH pulse peak was greater (P < 0.05) in T overfed ewes (4.59 ± 0.49 ng/mL) compared with T maintenance (2.19 ± 0.61 ng/mL) and Control ewes (2.58 ± 0.53 ng/mL). Additionally, amplitude of LH pulses was greater (P < 0.05) in T overfed ewes (2.66 ± 0.39 ng/mL) compared with T maintenance (1.03 ± 0.48 ng/mL) and tended (P = 0.089) to be greater in T overfed compared with Control ewes (1.41 ± 0.42 ng/mL). LH pulse peak and amplitude in T maintenance did not differ from Control ewes. In conclusion, failure of GD 60 to 90 T treatment to increase GnRH responsiveness as opposed to our earlier finding of increased responsiveness in GD 30 to 90 T-treaded sheep indicates that the susceptibility window for programming pituitary hypersensitivity to GnRH lies between GD 30 to 60. Postnatal obesity may act as an independent activational signal in amplifying the pituitary sensitivity to GnRH in female sheep. This premise is supported by observations that obesity exacerbates pituitarymediated LH hypersecretion in women with PCOS. Research support: NIH-NICHD (R01HD099096). [ABSTRACT FROM AUTHOR]
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- 2023
- Full Text
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5. Postnatal Obesity Amplifies the Effect of Prenatal Testosterone Excess in Reducing the Progesterone Negative Feedback Sensitivity in First-Generation Ewes.
- Author
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Gurule, Sara C., Sustaita-Monroe, Jessica F., King, Leslie, Garza, Viviana, West, Sarah, Weynand, Morgan, Ecord, Emily, Padmanabhan, Vasantha, and Cardoso, Rodolfo C.
- Subjects
PROGESTERONE ,EWES ,CHILDBEARING age ,POLYCYSTIC ovary syndrome ,LAMBS ,TESTOSTERONE ,PROGESTERONE receptors - Abstract
Polycystic ovary syndrome (PCOS) is the leading cause of anovulatory infertility in women of reproductive age. Women with PCOS exhibit reduced sensitivity of the GnRH neuronal system to the inhibitory effects of both progesterone and estradiol. Additionally, obesity amplifies the severity of the PCOS phenotype. In sheep, testosterone (T) excess during gestational days (GD) 30-90 and 60-90 reduces neuroendocrine sensitivity to the progesterone negative feedback and recapitulates the PCOS phenotype. This study investigated the contribution of postnatal obesity in amplifying or mitigating the effects of midgestational T excess in disrupting the responsiveness to progesterone negative feedback in sheep. Suffolk ewes received T propionate (T; 100 mg i.m.) or corn oil (CO; vehicle) twice weekly from GD 60-90 (term = 147 d). At 5 mo of age, F
1 T lambs were assigned randomly to either a maintenance (100% of NRC requirements) or overfed diet (130% of NRC requirements) and control lambs were fed the maintenance diet. At 22 mo of age, F1 ewes (n = 8/group) were synchronized with two injections of PGF2α 11 d apart. After the second PGF2α administration, blood samples were collected daily for 14 d and progesterone concentrations were determined via radioimmunoassay. Ewes that were confirmed to be cycling and in the mid-luteal phase based on progesterone concentrations (progesterone = 1 ng/ml on day 10 and = 0.5 ng/ml on days 8-9 and 11-12) were used for LH pulse characterization. On day 10 after PGF2α synchronization (mid-luteal phase), blood samples were collected every 15 min for 6 h to characterize LH pulsatile secretion via radioimmunoassay. Data were analyzed as one-way ANOVA with Tukey's HSD post-hoc analysis. Frequency of LH pulses was greater (P < 0.05) in T maintenance (3.75 ± 0.41 pulses/6h) and T overfed ewes (3.50 ± 0.34 pulses/6h) compared with controls (2.00 ± 0.37 pulses/6 h). Luteinizing hormone pulse amplitude was greater (P < 0.05) in T overfed (2.03 ± 0.15 ng/mL) compared with T maintenance (1.44 ± 0.17 ng/mL), but not to controls (1.74 ± 0.21 ng/mL). Also, average LH concentration was greater (P < 0.05) in T overfed (2.03 ± 0.24 ng/mL), but not T maintenance (1.31 ± 0.35 ng/mL), compared with controls (0.93 ± 0.30 ng/mLl). In conclusion, these findings demonstrate the activational role of postnatal obesity in amplifying prenatal T-induced alterations in tonic LH secretion during progesterone negative feedback. The activational effect of postnatal obesity in increasing LH secretion and consequently thecal androgen production is likely a contributor to the severity of hyperandrogenic status in women with PCOS. Research support: NIH-NICHD (R01HD099096). [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
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6. Effects of Prenatal Testosterone Excess on Puberty Attainment of First-Generation ewe Lambs.
- Author
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Gurule, Sara C., Sustaita, Jessica F., Landers, Renata, King, Leslie, Garza, Viviana, Bynum, Sarah, Arrott, Dylan, Padmanabhan, Vasantha, and Cardoso, Rodolfo C.
- Subjects
PUBERTY ,LAMBS ,EWES ,POLYCYSTIC ovary syndrome ,CORN oil ,TESTOSTERONE - Abstract
Prenatal testosterone excess causes reproductive perturbations in sheep that recapitulate those seen in women with polycystic ovary syndrome (PCOS). Obesity has a significant role in the development and severity of the PCOS phenotype. Our objective was to investigate the effects of testosterone excess from gestational days (GD) 60-90 (unlike the GD 30-90 model, these animals are not virilized) and postnatal body weight (BW) gain on puberty in firstgeneration ewe lambs. Pregnant Suffolk ewes received testosterone propionate (T; 100 mg) or corn oil (C) i.m. twice weekly from GD 60-90 (term=147d). Ewe lambs were weaned ~3 mo of age. Control and T lambs were assigned to gain either 0.3 kg/d (C and T-maintenance) or 0.4 kg/d (T-overfed). Maintenance diet was designed to promote optimal growth without excess fat deposition. Overfed ration was designed to achieve a BW ~30% above that of maintenance. Progesterone concentrations were measured via radioimmunoassay in blood samples collected twice weekly from ewe lambs (n=15/group) during the first breeding season. Puberty was defined as when progesterone concentrations were < 0.5 ng/mL for four consecutive samples followed by three consecutive samples =0.5 ng/mL. Six animals (C, n=1; T-maintenance, n=3; T-overfed, n=2) did not attain puberty during the study and puberty was assigned as last day of sampling. Average daily gain was not different among treatments (C, 0.23±0.02kg; T-maintenance, 0.25±0.01kg; T-overfed, 0.27±0.02kg). Age at puberty did not differ between groups (C, 274.6±9.9d; T-maintenance, 270.0±11.3d; T-overfed, 266.0±10.2d). Similarly, BW at puberty did not differ across treatments (C, 50.44±2.2kg; T-maintenance, 52.5±2.4kg; T-overfed, 57.3±2.5kg). In conclusion, unlike GD 30-90 exposure which advanced puberty, GD 60-90 exposure did not affect age and BW at puberty in ewe lambs. Collectively, these studies suggest that GD 30-60 is a critical developmental window in which prenatal testosterone excess advances puberty in female sheep. Research support: NIH-NICHD (R01HD099096). [ABSTRACT FROM AUTHOR]
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- 2022
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7. A Priming Effect of Luteinizing Hormone Releasing Hormone on Bovine Pituitary Cells In Vitro
- Author
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Padmanabhan, Vasantha, Kesner, J. S., and Convey, E. M.
- Abstract
The capacity of pituitary glands to release luteinizing hormone (LH) in response to LH-releasing hormone (LHRH) in vivomay be increased by previous frequent exposures to small quantities of LHRH. This phenomenon, called LHRH self-priming, may play an important role in the control of LH secretion. Our initial objective was to determine whether LHRH self-priming occurs via a direct effect on bovine pituitary cells. Subsequently, we studied the effects of interval between LHRH exposures and source of pituitary glands (steers versuscows) on LHRH self-priming. Cells from bovine anterior pituitary glands were dispersed and mixed with Sephadex-G25, and the mixture was poured into glass columns. Columns were superfused and effluent medium was assayed for LH. Challenges were .1 ng LHRH/ml or 0 ng LHRH/ml (sham) each for 10 minutes. In one experiment, quantity of LH released by a second exposure to LHRH averaged 124 ± 6 ng/ml, which was greater than that released in response to an LHRH challenge (90 ± 4) given 40 min earlier. In a second experiment, variables were LHRH sequence (sham-LHRH versusLHRH-LHRH) and interval between challenges (40, 80, 160 and 320 min). Quantities of LH released in response to LHRH following the sham challenge or the first of two LHRH challenges were not different. However, LH released by a second LHRH challenge was 48, 39 and 48% greater (P<.01) than that released by the first when the interval between challenges was 40, 80 and 160 min, respectively. But when the interval was 320 min, no LHRH self-priming occurred. In a third experiment, variables were LHRH sequence (sham-LHRH versusLHRH-LHRH) and sex of the pituitary gland donor (cows versussteers). Interval between challenges was 50 minutes. Quantity of LH released after the second LHRH challenge was 50% greater (P<.01) than that released after the first LHRH challenge when cells were from pituitary glands of cows. Self-priming did not occur when cells were from pituitary glands of steers. However, this experiment compared a pool of pituitary cells from steers with one from cows, so there was no estimate of individual animal variation. Thus, our data do not prove that this difference exists but merely raises that possibility. We conclude that LHRH can self-prime bovine pituitary cells and that the degree to which priming occurs may be dependent upon the interval between exposures to LHRH.
- Published
- 1981
- Full Text
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