Inducción hormonal del desove con GnRHa y su modulación con hormona del crecimiento en trucha arcoiris (Oncorhynchus mykiss)
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2000
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Facultad/escuela
Idioma
es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
La inducción del desove en peces, es realizada usualmente a través de la inyección
de la hormona liberadora de gonadotropina (GnRH). Sin embargo, este tratamiento puede
comprometer la viabilidad de las ovas, ya que las señales endocrinas que regulan la
maduración y ovulación del ovocito se ven forzadas. De esta manera, es importante conocer
estas señales endocrinas que están en relación con este proceso, como la hormona del
crecimiento (GH) y el factor de crecimiento de tipo insulínico (IGF).
En este estudio, se realizaron inyecciones intraperitoneales de 20 ug/Kg p.c. de desGly10
Ala6-LHRH-etilamida (GnRHa), con y sin. hormona del crecimiento bovina (bGH)
con una concentración de 100 ug/Kg p.c., administrada a través de un vector oleoso o salino
en hembras de truchas arcoiris. Semanalmente fue registrado cada desove y se tomaron
muestras de sangre para la determinación de la concentración de testosterona (T), 17f3-
estradiol (17f3-E) y 17a-hidroxiprogesterona (17a-HP) a través de RIA. Las ovas obtenidas
se fecundaron con un pool de semen y fueron incubadas hasta las 70 unidades térmicas
acumuladas (UTA), momento en el cual la tasa de desarrollo embrionario fue evaluada.
La coinyección de GnRHa y bGH mostraron una cinética menor en la tasa de
desove que en el tratamiento de GnRHa. Durante el periodo periovulatorio 17a-HP mostró
una media de 2,7 ±. 0,2 ng/ml, mientras que al momento de la ovulación_ llegó a 61,0 ±. 5,5
ng/ml. Por su parte GnRHa oleoso presentó bajos niveles de embrionación respecto a la
coinyección (P<0,05). Sin embargo, ambos tratamientos mostraron niveles
significativamente más bajos de 17a-HP respecto al control (P<0,05). La mayoría de los
niveles de testosterona y 17f3-estradiol, no mostraron disferencias significativas respecto de
. grupo control-vector.
Estos resultados muestran efectos positivos del tratamiento con bGH en la inducción
al desove, sugiriendo ser una señal alternativa o complementaria en la maduración (calidad
de las ovas) y proceso de ovulación.
The fish spawning induction is usually assayed by the administration of synthetic analog gonadotropin releasing hormone (GnRHa), but this treatment can induce deleterious effects in egg viability. Then, a deficiency in oocyte maturation and ovulation endocrine signals can be forced by this treatment. For this respect, is important to know other endocrine signals, like growth hormone (GH) and insulin like growth factor (IGF). In the present study, we assayed intraperitoneal injections of 20 J..l.g/fg des-Gly10[DAla6]- LHRH-etylamide (GnRHa), with or without bovine growth hormone (bGH) 100 J..l.g/Kg; injected through an oil or saline suspension in rainbow trout females two weeks before population spawning. Control were not manipulated and vector only received an oil/saline injection. Blood samples were taken weekly at the injection in control-vector group and at ovulation time for testosterone (T), 17J3-estradiol (17J3-E) and 17a-hidroxiprogesterone (17aHP) RIA determination. We also score the ovulation frequency through the reproductive period. Eggs were fertilized and incubated until 70 accumulate termic units (ATU), where the embrionic development was evaluated. The coinjection of GnRHa and bGH show lower spawning rate than GnRH single injection. During periovulatory time 17a-HP shows a mean of 2.7 ± 0.2 ng/ml, while at ovulation level increase to 61.0 ± 5.5 ng/ml (P<O.OOI). GnRHa in oil suspension present low levels of 17a-HP in early spawning fishes vs the control ones (P=0.006), associated with a poor embryonic development. GnRHa!bGH coinjection, keep high embryonic development, although 17a-HP even continue being low. Both treatments show a tendency to improve this progestogenic level in delayed spawnings. Most of all testosterone and 17J3 estradiol levels did not show significant differences from the control control-vector group. This results shows that GH positive effects are not through the stimulation of progestogenic pathway, suggesting an altemative or complementary signal in oocyte' maturation (egg quality) and ovulation process.
The fish spawning induction is usually assayed by the administration of synthetic analog gonadotropin releasing hormone (GnRHa), but this treatment can induce deleterious effects in egg viability. Then, a deficiency in oocyte maturation and ovulation endocrine signals can be forced by this treatment. For this respect, is important to know other endocrine signals, like growth hormone (GH) and insulin like growth factor (IGF). In the present study, we assayed intraperitoneal injections of 20 J..l.g/fg des-Gly10[DAla6]- LHRH-etylamide (GnRHa), with or without bovine growth hormone (bGH) 100 J..l.g/Kg; injected through an oil or saline suspension in rainbow trout females two weeks before population spawning. Control were not manipulated and vector only received an oil/saline injection. Blood samples were taken weekly at the injection in control-vector group and at ovulation time for testosterone (T), 17J3-estradiol (17J3-E) and 17a-hidroxiprogesterone (17aHP) RIA determination. We also score the ovulation frequency through the reproductive period. Eggs were fertilized and incubated until 70 accumulate termic units (ATU), where the embrionic development was evaluated. The coinjection of GnRHa and bGH show lower spawning rate than GnRH single injection. During periovulatory time 17a-HP shows a mean of 2.7 ± 0.2 ng/ml, while at ovulation level increase to 61.0 ± 5.5 ng/ml (P<O.OOI). GnRHa in oil suspension present low levels of 17a-HP in early spawning fishes vs the control ones (P=0.006), associated with a poor embryonic development. GnRHa!bGH coinjection, keep high embryonic development, although 17a-HP even continue being low. Both treatments show a tendency to improve this progestogenic level in delayed spawnings. Most of all testosterone and 17J3 estradiol levels did not show significant differences from the control control-vector group. This results shows that GH positive effects are not through the stimulation of progestogenic pathway, suggesting an altemative or complementary signal in oocyte' maturation (egg quality) and ovulation process.
Notas
Tesis (Ingeniero en Acuicultura)
Palabras clave
Trucha Arco Iris, Huevos