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Densytometric analysis of diosgenin in extracts from callus tissue of Polygonatum verticillatum (L.) All.

100%
Szybka-Hrynkiewicz P., Janeczko Z.
Biotechnologia
|
2004
|
issue 2
93-99
EN
In this study, we examined the effect of plant growth regulators (2, 4-D, 6-BAP) and steroidal hormone (17-beta-estradiol) on a quantity of diosgenin in callus tissue of Polygonatum verticillatum (L.) All. The callus grown in in vitro conditions on MS medium with: 1/1, 2/2, 5/5, 10/10 ([mg/dm3] 2,4-D/[mg/dm3] 6-BAP) and 1/1/1, 2/2/2, 5/5/5, 10/10/10 ([mg/dm3] 2,4-D/[M/dm3] 17beta-estradiol/[mg/dm3] 6-BAP) was used for the densytometric analysis to determine the presence of diosgenin. The content of diosgenin ranged from 0,0642 to 1,1458%. An increase in diosgenin content due to addition of 6-BAP and 2,4-D was observed. The developed procedure was estimated by statistical analysis which indicates that it can be used for routine analysis.
2
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Central estrogen-like effect of genistein on growth hormone secretion in the ewe

100%
Misztal T., Wankowska M., Gorski K., Romanowicz K.
Acta Neurobiologiae Experimentalis
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2007
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vol. 67
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issue 4
411-419
EN
The present study tested a hypothesis, whether plant-derived genistein influences the secretion of growth hormone (GH) in ewes, acting directly within the central nervous system (CNS). Starting six weeks after ovariectomy, ewes were infused intracerebroventricularly with genistein (n = 5) or 17beta-estradiol (n = 5), both in a total dose of 40 microg/400 microl/4 h, or with a vehicle (control, n = 5). All infusions were performed from 10:00 AM to 2:00 PM and blood samples were collected from 8:00 AM to 8:00 PM at 10-min intervals. Five genistein- and three vehicle-infused ewes were slaughtered the following morning. The plasma GH concentration was assayed by the radioimmunoassay method, and immunoreactivity of GH in the adenohypophysis was determined by immunohistochemistry. In genistein-infused ewes, mean plasma GH concentration was significantly higher during the whole period of infusion than the concomitant concentration in vehicle-infused ewes. However, examining data within group, GH secretion rose gradually, reaching a significant value during the second phase of genistein infusion. In 17beta-estradiol-infused animals, a significant increase in GH concentration was noted during the first two hours of the infusion, in comparison with vehicle-infused and also in comparison with genistein-infused ewes. Although a gradual increase in basic GH secretion continued in all treated groups during the afternoon and evening, mean plasma GH concentrations in genistein- and 17beta-estradiol-infused ewes were still significantly higher than in the vehicle-infused. The percentage of GH-positive cells in the adenohypophysis and the density of immunoreactive material in these cells decreased significantly in genistein-infused ewes, compared to the control, indicating diminished hormone storage. In conclusion, genistein as 17beta-estradiol, is an effective stimulator of GH secretion in ewes and may exert its effect at the level of the CNS.
3
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Neural systems mediating the negative feedback actions of estradiol and progesterone in the ewe

84%
Goodman R. L.
Acta Neurobiologiae Experimentalis
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1996
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vol. 56
|
issue 3
727-741
EN
The ewe shows a marked seasonal variation in the effect of ovarian steroids on pulsatile GnRH secretion.In the breeding season progesterone inhibits GnRH pulse frequency, while estradiol suppresses puilse amplitude.In anestrus, both steriods inhibit pulse frequency.The effects of progestrone in both seasons are mediated by endogenous opioid peptides (EOP) that act in the preoptic area (POA) and medial basal hypothalmus (MBH).However, knife cut studies indicate that actions in the MBH are most important.Moreover, blockade of EOP receptors activates GnRH perikarya in the MBH, but not those in the POA.Thus interactions between EOP and GnRH neurons within the MBH may be critical for progesterone negative feedback.The neural systems mediating estradiol suppression of GnRH pulse amplitude in the breeding season are largely unknown, although alpha-adrenergic neurons nay be involved.The seasonal variation in inhibition of GnRH pulse frequency by estradiol is postulated to be mediated by a group of dopaminergic (DA) neurons that have three important properties: (1)they inhibit GnRH pulse frequency; (2) their activity is stimulated by estradiol; and (3) they are functional in anestrus, but not the breeding season.Recent work examining the effects of lesions of DA neyrone and the ability of estradiol to induce Fos inDA cells srongly suggest that DA neurons in the retrochiasmatic area (A15) and POA (A14) have all three characteristics.We thus propose that these DA neurons are responsible for the seasonal variation in the ability of estradiol to inhibit GnRH pulse frequency.
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