Автор неизвестен - Krmulture in iran - страница 6

Страницы:
1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53 

0.10c

0.12d

0.04d

2.5

1.58

0.48

0.23

0.13

0.20

1.06

1.08

1.09

1.16

1.13

1.59

n=6

+

+

+

+

+

±

+

+

+

+

+

0.19d/a

0.03b/a

0.02a/a

0.01a/a

0.02a/a

0.05c

0.03c

0.02c/b

0.06c

0.06c

0.03d

2.5x3

1.44

0.49

0.19

0.12

0.23

1.04

0.04

0.32

0.13

0.45

0.07

n=6

+

+

+

+

+

+

+

+

+

+

+

 

0.15c/a

0.04c/a

0.02ab/a

0ab/a

0.02ab/a

0.06d

0.01 a

0.03bc/a

0ab

0.02c

0a

2.5

0   48   96 144 192 240 288 336 384 432 480 528

Hours after injection

Figure 1 Serum 176-estradiol level in pre-spawning female rainbow trout injected or not with Letrozole (mg AI kg-1). Each value represents the mean + standard error. Serum 176-esradiol (E2) levels which are similar (P>0.05) within each group are identified by the same letter before slash. Serum 176-esradiol (E2) levels which are similar (P>0.05) among the groups are identified by the same letter before slash. n= number of fish in each group. C= control .The       ▲andx indicate the different treatments

Treatment_17g-20fi-P (ng ml-1)/ hours after injection

 

0

6

24

48

96

144

192

288

384

480

528

C

n=6

0.29 +

0.03a/a

0.20 +

0.04a

0.27 +

0.03a/a

0.31 +

0.04a/a

0.10 +

0.04 a

0.17 +

0.03a/a

0.25 +

0.06a/a

0.18 +

0.06a

0.23 +

0.01a/a

0.16 +

0.05a/a

2.15 +

0.24 b

1.0

n=6

0.21 +

0.04a/a

1.16 +

0.06d

0.6 +

0.08b/b

1.69 +

0.08f/b

0.91 +

0.04c

0.57 +

0.04b/b

0.38 +

0.03a/a

0.58 +

0.03b

0.33 +

0.04a/b

0.39 +

0.03b/c

1.52 +

0.05e

2.5

n=6

0.26 +

0.02a/a

3.19 +

0.19d

2.36 +

0.07c/c

2.34 +

0.07c/c

3.47 +

0.11c

0.69 +

0.07b/b

0.36 +

0.02c/a

0.30 +

0.03a

0.48 +

0.05ab/c

0.27 +

0.03a/ bc

2.14 +

0.09c

2.5x3

n=6

0.25 +

0.01a/a

3.08 +

0.19c

2.29 +

0.05c/c

2.33 +

0.06c/c

3.56 +

0.12f

0.66 +

0.06b/b

2.60 +

0.04cd/b

3.15 +

0.17e

2.65 +

0.04cd/d

2.57 +

0.04cd/d

2.89 +

0.05de

4

0  48 96 144 192 240 288 336 384 432 480 528

Hours after injection

Figure 2 Serum 17a-206-P level in pre-spawning female rainbow trout injected or not with Letrozole (mg AI kg-1). Each value represents the mean + standard error. Serum 17a-206-P levels which are similar (P>0.05) within each group are identified by the same letter before slash. Serum 17a-206-P levels which are similar (P>0.05) among the groups are identified by the same letter before slash. n= number of fish in each group. C= control. The symbols       ▲andx indicate the different treatments.

Treatment testosterone (ng ml-1)/ hours after injection

 

0

6

24

48

96

144

192

288

384

480

528

C

2.01

1.80

1.60

2.60

3.04

3.54

4.47

4.96

5.73

6.07

6.81

n=6

±

±

±

±

±

±

±

±

±

±

±

0.07b

0.07ab

0.03a/a

0.04c/a

0.11d

0.06e/c

0.10f/c

0.0.19f/b

0.07g/c

0.16h/c

0.08i/c

1.0

3.18

3.39

2.61

2.64

3.17

2.97

3.29

3.40

3.39

3.47

3.57

n=6

±

±

±

±

±

±

±

±

±

±

±

0.19bc

0.24bc

0.06a/b

0.06c/b

0.04bc

0.04b/a

0.05bc/a

0.09bc/a

0.07bc/a

0.04c/a

0.05c/b

2.5

2.22

2.15

2.92

4.46

4.87

3.24

3.67

3.63

3.53

3.81

3.68

n=6

±

±

±

±

±

±

±

±

±

±

±

0.03a

0.01a

0.05b/c

0.04e/c

0.18f

0.06c/b

0.07d/b

0.06d/a

0.07d/a

0.07d/a

0.06d/b

2.5x3

2.29

2.11

2.96

4.42

5.24

3.25

3.41

3.69

5.47

4.80

2.77

n=6

±

±

±

±

±

±

±

±

±

±

±

 

0.04a

0.04a

0.04bc/c

0.07e/c

0.18g

0.04cd/b

0.16cd/ ab

0.27d/a

0.11g/b

0.14f/b

0.12b/a

7.5

0   48 96 144192 240 288 336 384432 480528 Hours after injection

Figure 3 Serum testosterone level in pre-spawning female rainbow trout injected or not with Letrozole (mg AI kg-1). Each value represents the mean ± standard error. Serum testosterone levels which are similar (P>0.05) within each group are identified by the same letter before slash. Serum testosterone levels which are similar (P>0.05) among the groups are identified by the same letter before slash. n= number of fish in each group. C= control . The symbols ♦, ■, ▲andx indicate the different treatments.

Figure 4 Effects of Letrozole on the oocyte diameter from pre- spawning female rainbow trout.Each bar represents the mean± SEM from females each treatment group.Oocyte diameters which are similar (P>0.05), as determined by Duncan's test among groups (C= control, LET1= 1 mg Letrozole kg-1, LET2.5= 2.5 mg Letrozole kg-1and LET 3x2.5= 2.5 mg Letrozole kg-1weekly) are identified by the same superscript letter. Number of fish used in each group is three.

 

a

 

 

0

0

0

0

 

LET2.5

Treatment

LET 3x2.5

Figure 5 Effects of Letrozole on the gonadosomatic index(GSI) from pre- spawning female rainbow trout. Each bar represents the mean± SEM from females each treatment group.GSI which are similar (P>0.05), as determined by Duncan's test among groups (C= control, LET1= 1 mg Letrozole kg-1, LET2.5= 2.5 mg Letrozole kg-1and LET 3x2.5= 2.5 mg Letrozole kg-1weekly) are identified by the same superscript letter. Number of fish used in each group is three. Gonadosomatic index= ovary weight /body weight x100.

9

b

b

6

3

0

C

LET 1

In several teloest species, reduced growth and lower flesh quality coincides with sexual maturation and precocious maturation is a problem in commercial fish farming. Therefore, reliable methods to control the onset of puberty are required (Afonso, Iwama et al. 1999). Different strategies have been developed in order to circumvent this drawback (Lee. et al., 2004). Our aim of studying the effect of Letrozole was to assess this approach as a possible method of controlling several maturities in trout. Efficiency in blocking pubertal maturation might also be imported by starting injection of aromatase inhibitor much earlier prior to puberty onset (Afonso, Iwama et al. 1999, Ankley, Kahl et al. 2002). Due to aromatase gene expression and activity are high at pre-spawning adult females, we chosed this life period (Halm. et al., 2001, Panter. et al., 2004). At time 0 (as shown in Fig.1), the low levels of 17a-20p-P and the high levels of serum 17P-estradiol observed in all groups showed that females were before the final maturation process. 17P-estradiol are key components controlling oocyte growth(Campbell. et al., 2003). Levels similar at time 0 were reported by Afonso et al (1999) in vitellogenic Coho salmon. At time 0 (as shown in Fig.1), the low levels of 17a-20p-P and the high levels of serum 17P-estradiol observed in all groups showed that females were before the final maturation process. 17P-estradiol are key components controlling oocyte growth (Campbell, Dickey et al. 2003). Levels similar at time 0 were reported by Afonso et al (1999) in vitellogenic Coho salmon. Basal E2 levels were twice as high in untreated females compared to treated females from 24 h up to 96 h after injection with Letrozole and serum E2 levels were significantly lower in females injected with 2.5 mg AI kg-1 weekly. Also decreases in E2 levels (6 h after injection) in the groups injected with Letrozole suggest that this anti- steroid inhibit aromatase, the enzyme that converts androgens to estrogens. Synthetic estrogen level possibly through two mechanisms, one mechanism is through aromatization of testosterone and the other is a decrease in converting steroid in to estrogen. Our result shows that a carful time and dose ­

response study has to be performed to determine dosages and times that will influence on changes of steroid hormones. There are no previous studies of the effects of Letrozole on serum steroid levels in females of different species of fish before spawning but similar results were obtained by Kelloff, Lubet, Lieberman, Eisenhauer, Steele, Crowell, Hawk, Boone and Sigman (1998) that a dose responsive increase in blood serum steroid was observed in trout injected with 50 mg Fadrozole kg-1per day. Shilling et al (1999) used Letrozole (CGS20267) and aminoglotethimide (AG) as non- steroid invitro for activity in trout ovarian microsomes and showed that Letrozole reduced aromatase activity a maximum of 90% in dose- dependent manner. But Letrozole and Clorimazole fed to juvenile rainbow trout at doses up to 1000 ppm for 2 weeks were not effective in suppressing 17 P- estradiol levels (Shilling, Carlson et al. 1999). Our invivo data show that the mechanism and efficiency of inhibition of Fadrozole are different. Also similar E2 levels have been exhibited in vitellogenic Coho salmon. Afonso et al (1999)demonstrated that the aromatase inhibitor Fadrozole was capable of reducing E2 biosynthesis in female Coho salmon In the adult female rat, Letrozole (0.3-1 mg kg-1 daily) completely interrupted ovarian cyclicity and reduced uterine weight and serum estradiol (E2) concentration (Bhatnagar. et al., 1990, Bhatnagar. et al., 1993, Schieweck. et al., 1993). It took a 4xconcentrated (10 mg AI kg-1) sample of Fadrozole (Afonso, Iwama et al. 1999) to inhibit aromatase to the same levels as the Letrozole at 2.5 mg AI kg-1 which suggest differences in concentration of the compounds due to the anti- aromatase effect of Letrozole is very potent (Seralini and Moslemi 2001, Sun. et al., 2010). Our results indicate that groups injected with AI contain potent component that can suppress aromatase cytochrom P450 (Sioufi. et al., 1997, Haynes, Dowsett et al. 2003). Our results showed that in the groups injected with Letrozole, serum 17a-20P-P levels significantly increased at 6 h after injection (premature increase) and in the group injected with 2.5 mg AI kg-1 weekly demonstrated that serum E2 levels was declined up to 528h after injection, and serum 17a-20P-P levels significantly increased pre spawning and remained high from 192 to

528h after injection. But in the other two groups injected with Letrozole, the increase in serum17a-20P-P levels observed at pre-spawning (6 h after injection) was transient. Similar results were obtained by Afonso et al (1999) in vitellogenic Coho salmon. Letrozole had a global inhibitory effect on serum testosterone and estrogen in female trout. This is in accordance with the fact that in fish aromatase inhibitor plays a prominent role in the regulation of steroidogenesis (Piferrer. et al., 1994, Suzuki. et al., 2004, Uchida. et al., 2004). In this experiment, female trout in their one year were injected with Letrozole. Letrozole effect on ovarian development was assessed by oocyte diameter and GSI. The letrozole with 2.5 mg AI kg-1 weekly was efficient enough to decrease mean GSI and oocyte diameter that show the weekly injection of Letrozole has a specific effect in delaying ovarian development. The delay of sexual maturity previously observed after injection of Fadrozole in Coho salmon (Afonso, Iwama et al. 1999). Bhatnagar et al (1993)reported that Letrozole inhibits the conversion of androstendione to estrone in human and blocks estrogen- dependent uterine growth and negative feedback on FSH secretion. Also peter and Yu (1997) expressed that in teleosts estrogens are responsible for growth and maturation of oocytes and together with testosterone and progesterone, they regulate final oocyte maturation and ovulation (Lahnsteiner. et al., 2006).This suggests that estrogens are important for oocyte development in female fish and exposure to compounds that inhibit estrogen synthesis can affect sexual development in rainbow trout. In this study, due to transitory effect of Letrozole on Serum E2 levels in the other two groups didn t have affected on GSI and oocyte diameter. This is similar to finding of Afonso et al (1999) on Coho salmon.In conclusion, we show for the first time that Letrozole displayed marked inhibitory effect on gonad development and serum sex steroid in trout. Letrozole a synthetic aromatase inhibitore that belongs to a class of indirectly acting anti-estrogens can decrease synthesis of endogenous estrogens from androgens by aromatase inhibitor. The data suggest that those effects depend on the time and dosage of injection of Letrozole. The study also showed that weekly injections with Letrozole decreased GSI and oocyte

diameter in pre- spawning period of female trout. Technology of aromatase inhibitor might also be a promising method for controlling the onset of puberty in aquaculture species.

References

Afonso, L. O. B., G. K. Iwama, J. Smith & E. M. Donaldson (1999). "Effects of the aromatase inhibitor fadrozole on plasma sex steroid secretion and ovulation rate in female coho salmon, Oncorhynchus kisutch, close to final maturation. ." General and Comparative Endocrinology 113: 221-229.

Afonso, L. O. B., G. K. Iwama, J. Smith & E. M. Donaldson (2000). "Effects of the aromatase inhibitor fadrozole on reproductive steroids and spermation in male coho salmon (Oncorhynchus kistuch) during sexual maturation." Aquaculture 188(175-187).

Ankley, G. T., M. D. Kahl, K. M. Jensen, M. W. Hornung, J. J. Korte, E. A. Makynen & R. L. Leino (2002). "Evaluation of the aromatase inhibitor fadrozole in a short- term reproduction assay with the fathead minnow (Pimephales promelas)." Toxicological of Sciences 67: 121- 130.

Bajetta, E., N. Zilembo, E. Bichisao, P. Pozzi & L. Toffolatti (2000). "Steroidal aromatase inhibitors in eldery patients." Critical Reviews in Oncology Hematology 33: 137-142.

Bhatnagar, A. S., C. Batzl, A. Hausler & V. Nogu6s (1993). "The role of estrogen in the feedback regulation of follicle-stimulating hormone secretion in the female rat." Journal of Steroid Biochemistry and Molecular Biology 47: 161-166.

Bhatnagar, A. S., A. Hausler, K. Schieweck, M. Lang & R. Bowman (1990). "Highly selective inhibition of estrogen biosynthesis by CGS 20267, a new non-steroidal aromatase inhibitor." Journal of Steroid Biochemistry and Molecular

Biology 37: 1021-1027.

Campbell, B., J. T. Dickey & P. Swanson (2003). "Endocrine Changes During Onset of Puberty in Male Spring Chinook Salmon,Oncorhynchus tshawytscha." Biology of Reproduction 69: 2109-2117.

Guzman, J. M., B. Norberg, J. Ramos, Mylonas C. C. & E. L. Manan6s (2008). "Vitellogenin, steroid plasma levels and spawning performance of cultured female Senegalese sole (Solea senegalensis)." General and Comparative Endocrinology 156: 285-297.

Halm, S., M. Rand-Weaver, J. P. Sumpter & C. R. Tyler (2001). "Cloning and molecular characterization of an ovarian-derived (brain-like) P450 aromatase cDNA and development of a competitive RT-PCR assay to quantify its expression in the fathead minnow (Pimephales promelas)." Fish Physiology and Biochemistry 24: 49-62.

Harris, J. & D. J. Bird (2000). "Modulation of the fish immune system by hormones." Veterinary Immunology and Immunopathology 77: 163-176.

Haynes, B. P., M. Dowsett, W. R. Miller, J. M. Dixon & A. S. Bhatnagar (2003).

"The pharmacology of letrozole." Journal of Steroid Biochemistry 87: 35-45.

Kelloff, G. J., R. A. Lubet, R. Lieberman, K. Eisenhauer, V. E. Steele, J. A.

Crowell, E. T. Hawk, C. W. Boone & C. C. Sigman (1998). "Aromatase inhibitors as potential cancer chemopreventives." Cancer Epidemiol Biomarkers

Prev 7: 65-78.

Lahnsteiner, F., B. Berger, M. Kletzl & T. Weismann (2006). "Effect of 17beta-estradiol on gamete quality and maturation in two salmonid species." Aquatic Toxicology 79: 124-131.

Lange, I. G., A. Hartel & H. H. H. Meyer (2003). "Evolution of oestrogen functions in vertebrates." Journal of Steroid Biochemistry 83: 219-226.

Lee, P., H. King & N. Pankhurst (2004). "Prelimnary assessment of sex inversion of farmed Atlantic salmon by dietary and immersion androgen treatments.N. AM. ." Aquaculture 66: 1-7.

LI, G. L., X. C. Lin & H. R. Lin (2005). "Aromatase inhibitor letrozole induces sex inversion in the protogynous red spotted grouper (Epinephelus akaara)." Acta Physiologica Sinica 57: 473-479.

Navas, J. M. & H. Segner (2000). "Antiestrogenicity of beta-naphthoflavone and PAHs in cultured rainbow trout hepatocytes: evidence for a role of the arylhydrocarbon receptor." Aquatic Toxicology 51: 79-92.

Noaksson, E., U. Tjamlund, A. T. C. Bosveld & L. Balk (2001). "Evidence for

endocrine disruption in perch (Perca fluviatilis) and roach (Rutilus rutilus) in a remote Swedish lake in the vicinity of a public refuse dump." Toxicology and Applied Pharmacology 174: 160-176.

Panter, G. H., T. H. Hutchinson, K. S. Hurd, A. Sherrenb, R. D. Stanleya & C. R.

Tylerc (2004). "Successful detection of (anti-)androgenic and aromatase inhibitors in pre-spawning adult fathead minnows (Pimephales promelas) using easily measured endpoints of sexual development." Aquatic Toxicology 18: 11­21.

Peter, R. E. & K. L. Yu (1997). "Neuroendocrine regulation of ovulation in fishes: basic and applied aspects." Reviews in Fish Biology and Fisheries 7: 173-197.

Piferrer, F., S. Zanuy, M. Carrillo, Solar. I. I., Devlin. R.H. & Donaldson. E.M. (1994). "Brief treatment with an aromatase inhibitor during sex differentiation causes chromosomally female salmon to develop as normal, functional males." Journal of Experimental Zoology 270: 244-262.

Schieweck, K., A. S. Bhatnagar, C. Batzl & M. Lang (1993). "Anti-tumor and endocrine effects of non-steroidal aromatase inhibitors on estrogen-dependent rat mammary tumors." Journal of Steroid Biochemistry and Molecular Biology 44:

633-636.

Selvaraj, N., G. Shetty, K. Vijayalakshmi, Bhatnagar A. S. & N. R. Moudgal (1994). "Effect of blocking oestrogen synthesis with a new generation aromatase inhibitor CGS 16949A on follicular maturation induced by preguant mare serum gonadotropin in the immature rat." Journal of Endocrinolog 142: 563-570.

S6ralini, G. & S. Moslemi (2001). "Aromatase inhibitors: past, present and future." Molecular and Cellular Endocrinology 178: 117-131.

Shilling, A. D.,   D. B. Carlson & D. E. Williams (1999). "Rainbow trout,

Oncorhynchus mykiss, as a model for aromatase inhibition." Journal of Steroid Biochemistry and Molecular Biology 70: 89-95.

Sioufi, A.,  N. Gauducheau,  V. Pineau,  F. Marfil,  A. Jaouen,  J. M. Cardot, J.

Страницы:
1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53 


Похожие статьи

Автор неизвестен - 13 самых важных уроков библии

Автор неизвестен - Беседы на книгу бытие

Автор неизвестен - Беседы на шестоднев

Автор неизвестен - Богословие

Автор неизвестен - Божественность христа