Pubertal changes in the secretion of gonadotropic hormones, testicular gonadotropic receptors and testicular function in the ram

Yarney, T.A.; Sanford, L. M.

doi:10.1016/0739-7240(89)90016-7

Cited by 15 publications

(29 citation statements)

References 36 publications

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“…La concentración promedio de LH siguió un patrón similar a lo reportado previamente para corderos Blackbelly (14) y varias razas de lana (1,2,3,21,22) . Se observaron concentraciones bajas durante las primeras semanas de vida (2,3) , alcanzando concentraciones máximas entre las 11 y 13 semanas de edad, dependiendo de la raza (3,22) , seguido por una disminución o variaciones mínimas a partir de entonces.…”

Section: Discussionunclassified

“…Se observaron concentraciones bajas durante las primeras semanas de vida (2,3) , alcanzando concentraciones máximas entre las 11 y 13 semanas de edad, dependiendo de la raza (3,22) , seguido por una disminución o variaciones mínimas a partir de entonces. En el presente estudio, se detectaron pulsos de baja amplitud desde las 2 semanas de edad, lo cual coincide con lo reportado para razas de lana (1,21) , lo que indica que, aunque inmaduro, existe un eje reproductivo funcional a edades muy tempranas.…”

Section: Discussionunclassified

“…En el presente estudio, se detectaron pulsos de baja amplitud desde las 2 semanas de edad, lo cual coincide con lo reportado para razas de lana (1,21) , lo que indica que, aunque inmaduro, existe un eje reproductivo funcional a edades muy tempranas. La amplitud de los pulsos a los 28 días fue similar a la reportada previamente para razas de lana de la misma edad (22) . La frecuencia de pulsos a las 2 semanas fue mayor en los corderos del presente estudio, comparado con corderos de razas de lana de un mes de edad (22) , en los que la frecuencia no alcanzó valores comparables a los corderos de este estudio hasta los 90 días.…”

Section: Discussionunclassified

“…La amplitud de los pulsos a los 28 días fue similar a la reportada previamente para razas de lana de la misma edad (22) . La frecuencia de pulsos a las 2 semanas fue mayor en los corderos del presente estudio, comparado con corderos de razas de lana de un mes de edad (22) , en los que la frecuencia no alcanzó valores comparables a los corderos de este estudio hasta los 90 días.…”

Section: Discussionunclassified

“…El aumento progresivo de las concentraciones y la amplitud de los pulsos de T coincide con lo encontrado anteriormente en razas de lana (1,4,22) ; éste es inicialmente desencadenado por el aumento de la frecuencia y (o) magnitud de los pulsos de LH (4,21,24) , y por el incremento de la actividad esteroidogénica testicular y la capacidad de respuesta a la estimulación LH (2,21,22) . A pesar de la disminución de la secreción de LH después de la semana 12, las concentraciones de T continuaron aumentando hasta la semana 24; se ha observado que durante este tiempo aumenta el número de células de Leydig (25) y el número de receptores para LH (22,26) , se mejora la actividad enzimática genotype and genotype by age interaction were not significant.…”

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Development of the endocrine reproductive axis in hair breed ram lambs

Montiel-Olguín

Ávila

Amezcua

et al. 2016

Rev. Mex. Cienc. Pecu.

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RESUMENLos objetivos fueron caracterizar los perfiles de LH y testosterona (T) y la respuesta a GnRH en corderos de pelo. Estudio 1: se utilizaron corderos Blackbelly (n=4), Pelibuey (n=5), Blackbelly x Pelibuey (Cruzas; n=8). A las 2, 4, 8, 12, 16, 20 y 24 semanas de edad, se obtuvieron muestras de sangre cada 15 min durante 6 h, para caracterizar los perfiles de LH y T. No hubo diferencia entre genotipos a ninguna edad, para ninguna variable de LH y T (P>0.05); el efecto de la edad fue significativo (P<0.05): la concentración promedio de LH fue menor en la semana 2 (P<0.05), alcanzó el valor más alto en la 12, y disminuyó en la 16 (P<0.05). La concentración promedio de T aumentó constantemente entre 2 y 24 semanas (P<0.05). Estudio 2: se utilizaron corderos Blackbelly (n=4), Pelibuey (n=4), Cruzas (n=4). A las mismas edades, los corderos se desafiaron con GnRH (3, 9, 27 ng•kg -1 peso) y se obtuvieron muestras de sangre entre -15 y 180 min. En las semanas 8 y 12, la respuesta de LH fue mayor en los corderos Pelibuey, en comparación con Blackbelly. La respuesta de T tendió a ser diferente entre genotipos (P<0.10), con Blackbelly mostrando la menor respuesta. En conclusión, el desarrollo de los perfiles de LH y T no fue diferente entre genotipos, pero los corderos Pelibuey presentaron mayor capacidad de respuesta a GnRH en las semanas 8 y 12; es necesario determinar si estas diferencias tienen implicaciones sobre la capacidad reproductiva de los animales adultos.PALABRAS CLAVE: Blackbelly, Pelibuey, LH, Testosterona, Desarrollo sexual. ABSTRACTThe objectives were to characterize the profiles of LH and testosterone (T) and the response to GnRH administration in hair ram lambs. Study 1: seventeen lambs were used: Blackbelly (n=4), Pelibuey (n=5), Blackbelly x Pelibuey (Crossbred; n=8). At 2, 4, 8, 12, 16, 20 and 24 wk of age, blood samples were collected every 15 min for 6 h, to characterize LH and T profiles. There was no significant difference between genotypes at any age, for any variable of LH and T profiles (P>0.05). The effect of age was significant (P<0.05): mean LH concentration was lower on wk 2 (P<0.05), achieved the highest value on wk 12, and decreased on wk 16 (P<0.05). Mean T concentration increased steadily between wk 2 and 24 (P<0.05). Study 2: twelve lambs were used: Blackbelly (n=4), Pelibuey (n=4), Crossbred (n=4). At the same ages, lambs were challenged with GnRH (3, 9, 27 ng•kg -1 BW) and blood samples were obtained between -15 and 180 min from GnRH administration. On wk 8 and 12, LH response to GnRH was greater in Pelibuey, as compared with Blackbelly. Testosterone response tended to be different between genotypes (P<0.10), with Blackbelly showing the smallest response. In conclusion, the sexual endocrine development, as evaluated by the non-stimulated LH and T profiles, was not different among genotypes; however, Pelibuey elicited the greatest responsiveness to GnRH administration at 8 and 12 wk of age. Whether or not such differences have implications on the reproductive capacity of the adul...

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Section: Discussionunclassified

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Development of the endocrine reproductive axis in hair breed ram lambs

Montiel-Olguín

Ávila

Amezcua

et al. 2016

Rev. Mex. Cienc. Pecu.

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Prolactin in the Male: 25 Years Later

Bartke

2004

Journal of Andrology

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In an article published 25 years ago in the first volume of the Journal of Andrology (Bartke et al, 1980), we reported evidence of involvement of prolactin (PRL) in the control of testicular growth in the golden hamster. In this seasonally breeding species, testes undergo regression in the fall and recover their size and activity the following spring. PRL-secreting transplants of anterior pituitaries augmented the stimulatory effect of treatment with human chorionic gonadotropin on the recrudescence of the regressed testes, while treatment with an inhibitor of PRL release, bromocriptine, delayed recrudescence of the testes and the seminal vesicles induced by exposure to long photoperiods. Role of PRL in the Control of Seasonal Breeding in the Male HamsterStudies conducted in our laboratory following the abovereferenced report of the effects of bromocriptine (Bartke et al, 1980) reaffirmed the role of photoperiod-induced alterations in plasma PRL levels in the control of seasonal transitions between periods of full testicular activity and testicular quiescence in the golden hamster and identified a number of mechanisms involved in the actions of PRL. In the male golden hamster, PRL acts at multiple levels of the hypothalamic-pituitary-testicular axis. In the hypothalamus, it modifies the turnover of neurotransmitters involved in the control of the pituitary (Steger et al, , 1984. In the pituitary, it influences the number of androgen receptors (Prins et al, 1988). Actions of PRL on the hypothalamic-adenohypophyseal system result in the stimulation of follicle-stimulating hormone (FSH) synthesis and release Steger et al, 1983;Carrillo et al, 1984) and reduction of the sensitivity of gonadotropin release to negative testosterone feedback Our studies of the role of PRL in seasonal breeders were supported by NICHD.Correspondence to: Dr Andrzej Bartke, Departments of Physiology and Internal Medicine, Southern Illinois University School of Medicine, 801 N Rutledge, Springfield, IL 62794-9628 (e-mail: abartke@siumed.edu).Received for publication May 7, 2004; accepted for publication May 8, 2004. ( Bartke et al, 1984;Matt et al, 1984). This latter effect is of particular interest, because the major shifts observed in the sensitivity of luteinizing hormone (LH) and FSH release to feedback control by gonadal steroids accompany annual cycles of reproductive activity in both sexes of many (presumably all) seasonal breeders and are critically important for transitions between reproductive activity and quiescence. Reduced sensitivity of the hypothalamus and the pituitary to negative feedback of sex steroids during annual reactivation of the gonads resembles the endocrine changes that take place during puberty in both seasonal and nonseasonal breeders, including humans.In the hamster testis, PRL, along with the gonadotropins, regulates the expression of its own receptors (Klemcke et al, 1984(Klemcke et al, , 1986Amador et al, 1985) and LH receptors (Bex et al, 1978; and enhances the responsiveness of Leydig cells to LH stim...

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Testicular development in male lambs prenatally exposed to a high‐starch diet

Mossa

Bebbere

Ledda

et al. 2018

Molecular Reproduction Devel

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Maternal nutrition during critical gestation periods impacts on offspring in later life; effects of high-starch maternal diet on testicular development in lambs were addressed. Dairy ewes were fed diets providing either 27% (Starch, S) or 11% (Fiber, F) of starch from mating to lambing (∼147 days; S147, F147) or for the last 75 days of gestation (S75, F75). Testes of single male lambs were measured and then sampled for histological and gene expression analyses at selected ages. Testicular dimensions and weight were similar among groups, but the total area of seminiferous tubules increased with age and tended to be higher (p = 0.057) in lambs from starch- than fiber-fed ewes. Sertoli and germ cells number increased with age, but was not influenced by maternal diet. Transcript abundances of androgen receptor (AR), insulin-like growth factor 1 (IGF1), and hydroxysteroid (17-beta) dehydrogenase 3 (HSD17B3) was similar between S147 and F147 lambs (p > 0.1). Abundance of luteinizing hormone/choriogonadotropin receptor (LHCGR) and steroidogenic acute regulatory protein (STAR) was higher in young vs older lambs, whereas insulin-like growth factor 2 (IGF2) levels increased with age. The expression of vascular endothelial growth factor A (VEGFA), Anti-Müllerian hormone (AMH), IGF1, follicle stimulating hormone receptor (FSHR), and insulin-like growth factor 2 receptor (IGF2R) was not influenced by maternal diet or lamb age (p > 0.1). In conclusion, a high-starch maternal diet did not influence gene expression, but may have affected testicular structure in infant offspring, as seen by an increase in the total area of seminiferous tubules.

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Pubertal changes in the secretion of gonadotropic hormones, testicular gonadotropic receptors and testicular function in the ram

Cited by 15 publications

References 36 publications

Development of the endocrine reproductive axis in hair breed ram lambs

Development of the endocrine reproductive axis in hair breed ram lambs

Prolactin in the Male: 25 Years Later

Testicular development in male lambs prenatally exposed to a high‐starch diet

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