RESUMEN
The male gonadal tissue can be a sensitive target to the reprogramming effects of testosterone (T) during prenatal development. We have demonstrated that male lambs born to dams receiving T during pregnancy-a model system to the polycystic ovary syndrome (PCOS)-show a decreased number of germ cells early in life, and when adult, a reduced amount of sperm and ejaculate volume. These findings are a key to put attention to the male offspring of women bearing PCOS, as they are exposed to increased levels of androgen during pregnancy which can reprogram their reproductive outcome. A possible origin of these defects can be a disruption in the expression of the anti-Müllerian hormone (AMH), due to its critical role in gonadal function at many postnatal stages. Therefore, we addressed the impact of prenatal T excess on the expression of AMH and factors related to its expression like AP2, SOX9, FSHR, and AR in the testicular tissue through real-time PCR during the peripubertal age. We also analyzed the testicular morphology and quantified the number of Sertoli cells and germ cells to evaluate any further defect in the testicle. Experiments were performed in rams at 24 wk of age, hence, prior puberty. The experimental animals (T-males) consisted of rams born to mothers receiving 30 mg testosterone twice a wk from Day 30 to 90 of pregnancy and then increased to 40 mg until Day 120 of pregnancy. The control males (C-males) were born to mothers receiving the vehicle of the hormone. We found a significant increase in the expression of the mRNA of AMH and SOX9, but not of the AP2, FHSR nor AR, in the T-males. Moreover, T-males showed a dramatic decrease in the number of germ cells, together with a decrease in the weight of their testicles. The findings of the present study show that before puberty, T-males are manifesting clear signs of disruption in the gonadal functions probably due to an alteration in the expression pattern of the AMH gene. The precise way by which T reprograms the expression of AMH gene remains to be established.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Maduración Sexual/efectos de los fármacos , Ovinos/fisiología , Testículo/fisiología , Testosterona/administración & dosificación , Animales , Hormona Antimülleriana , Peso Corporal/efectos de los fármacos , Femenino , Masculino , Tamaño de los Órganos/efectos de los fármacos , Embarazo , Efectos Tardíos de la Exposición Prenatal , ARN Mensajero/genética , ARN Mensajero/metabolismo , Maduración Sexual/fisiología , Testosterona/farmacologíaRESUMEN
Prenatal exposure to excess testosterone has a profound impact on reproductive and metabolic functions in young and adult female sheep. Nevertheless, few studies have addressed the impact of prenatal exposure to an excess of androgens on reproductive and metabolic functions in males. The aim of the present study was to assess the impact of prenatal exposure to an excess of testosterone or dihydrotestosterone on the luteinizing hormone (LH) pulse characteristics during sexual development in male sheep. Control male sheep (C-males) and males born to mothers exposed to twice weekly injections of 30 mg testosterone or dihydrotestosterone from day 30-90 and 40 mg from day 90-120 of gestation (T-males, DHT-males) were studied at 5, 10, and 20 weeks of age, ages that represent infancy, early prepubertal, and late prepubertal stages of sexual development in this species, respectively. Patterns of LH pulsatility showed that T- and DHT-males exhibited a higher secretion of LH during the 6-h study and a higher amplitude of the LH pulses compared with C-males. Moreover, nadir of the pulses was higher in T- and DHT-males compared with C-males. Frequency of LH pulses, however, was not different within ages or between groups. These results show that males can be responsive to prenatal androgenization and suggest that treatment transiently alters the amplitude of LH pulses probably as the result of defects in the pituitary responsiveness pattern or in the gonadotropin-releasing hormone (GnRH) release pattern.
Asunto(s)
Andrógenos/efectos adversos , Hormona Luteinizante/sangre , Exposición Paterna/efectos adversos , Efectos Tardíos de la Exposición Prenatal/sangre , Ovinos/sangre , Ovinos/crecimiento & desarrollo , Animales , Dihidrotestosterona/efectos adversos , Femenino , Masculino , Embarazo , Efectos Tardíos de la Exposición Prenatal/etiología , Testosterona/efectos adversosRESUMEN
This study was designed to: 1) characterize the effect of ovulation-inducing factor (OIF) on pituitary LH secretion in ovariectomized (OVX) llamas; and 2) determine the effect of OIF on LH secretion in OVX llamas pretreated with estradiol-17ß (E-17ß) or estradiol benzoate (EB). In Experiment 1, intact and OVX llamas (n = 5 or 6 per group) were assigned to a two by two factorial design: 1) Intact llamas treated with 1 mL of phosphate buffered saline (PBS); 2) Intact llamas treated with 1 mg of purified OIF; 3) OVX llamas treated with 1 mL of PBS; or 4) OVX llamas treated with 1 mg of purified OIF. In Experiment 2, intact and OVX llamas (n = 5 or 6 per group) were randomly assigned to the following groups: 1) Intact llamas treated with 1 mg of purified OIF; 2) OVX llamas treated with 1.0 mL of PBS; 3) OVX llamas treated with 1.0 mg of purified OIF; 4) OVX llamas primed with E-17ß, followed by 1.0 mg of purified OIF. Experiment 3 was similar as described for Experiment 2, except that priming was done with EB. In Experiment 1, animal category by treatment and animal category by treatment by time interactions tended (P = 0.08) to affect LH concentration. The effect of OIF on LH released was partly restored (P < 0.05), to the values observed for the intact OIF-treated females, when OVX llamas were primed with E-17ß or BE (Experiments 2 and 3). We concluded that peripheral estradiol concentrations in llamas partially modulates the effect of OIF on pituitary LH secretion; however, other ovarian factor(s) could also participate in this modulatory action.
Asunto(s)
Camélidos del Nuevo Mundo/fisiología , Estradiol/metabolismo , Hormona Luteinizante/metabolismo , Ovario/fisiología , Hipófisis/metabolismo , Proteínas de Plasma Seminal/farmacología , Animales , Femenino , Masculino , Ovariectomía/veterinaria , Inducción de la Ovulación , Semen/químicaRESUMEN
Prolactin (PRL) is a pituitary hormone that plays important roles in mammalian reproductive physiology, specially lactation. The regulation of PRL secretion shows important species differences. To study PRL regulation in a subhuman primate, the Cebus apella, we developed an heterologous radioimmunoassay using an antibody against rhesus PRL (anti-m5PRL) and a Cebus apella pituitary extract as PRL standard. The assay has a sensitivity that allows measurements of cebus PRL in small amounts of Cebus apella plasma obtained from animals in different physiological conditions. Plasma cebus PRL concentrations (+/-SEM) varied in different reproductive stages. PRL concentration in adult Cebus apella females that have regular menstrual cycles (161.6 +/- 15.0 mIU/ml) was similar to that found in adult (100.3 +/- 7.6 mIU/ml) and prepuberal males (101.2 +/- 3.9 mIU/ml). PRL concentration was higher in pregnant (677.8 +/- 11.8 mIU/ml) and in nursing (625.0 +/- 47.0 mIU/ml) Cebus apella females than in 15-d post-partum non-nursing (369.0 +/- 19.0 mIU/ml) and cycling females. PRL concentration in Cebus apella newborns (719.0 +/- 49.2 mIU/ ml) was similar to that found in pregnant and nursing females, and higher than in the other females as well as adult and prepuberal males. These differences in PRL concentration in different physiological conditions are similar to that observed in humans and other primates. A PRL response to thyrotropin releasing hormone (TRH) was demonstrated in 2 nursing Cebus apella females, similar to the response found in nursing woman and rhesus. Altogether, the data presented support the proposal that the assay developed to measure PRL in Cebus apella is an adequate tool to study the physiology of PRL in this species.
Asunto(s)
Cebus/sangre , Prolactina/análisis , Radioinmunoensayo/métodos , Animales , Femenino , Masculino , Ciclo Menstrual/fisiología , Prolactina/fisiologíaRESUMEN
Prolactin (PRL) is a pituitary hormone that plays important roles in mammalian reproductive physiology, specially lactation. The regulation of PRL secretion shows important species differences. To study PRL regulation in a subhuman primate, the Cebus apella, we developed an heterologous radioimmunoassay using an antibody against rhesus PRL (anti-m5PRL) and a Cebus apella pituitary extract as PRL standard. The assay has a sensitivity that allows measurements of cebus PRL in small amounts of Cebus apella plasma obtained from animals in different physiological conditions. Plasma cebus PRL concentrations (+/-SEM) varied in different reproductive stages. PRL concentration in adult Cebus apella females that have regular menstrual cycles (161.6 +/- 15.0 mIU/ml) was similar to that found in adult (100.3 +/- 7.6 mIU/ml) and prepuberal males (101.2 +/- 3.9 mIU/ml). PRL concentration was higher in pregnant (677.8 +/- 11.8 mIU/ml) and in nursing (625.0 +/- 47.0 mIU/ml) Cebus apella females than in 15-d post-partum non-nursing (369.0 +/- 19.0 mIU/ml) and cycling females. PRL concentration in Cebus apella newborns (719.0 +/- 49.2 mIU/ ml) was similar to that found in pregnant and nursing females, and higher than in the other females as well as adult and prepuberal males. These differences in PRL concentration in different physiological conditions are similar to that observed in humans and other primates. A PRL response to thyrotropin releasing hormone (TRH) was demonstrated in 2 nursing Cebus apella females, similar to the response found in nursing woman and rhesus. Altogether, the data presented support the proposal that the assay developed to measure PRL in Cebus apella is an adequate tool to study the physiology of PRL in this species
Asunto(s)
Animales , Femenino , Cebus/sangre , Prolactina/análisis , Radioinmunoensayo/métodos , Ciclo Menstrual/fisiología , Prolactina/fisiologíaRESUMEN
Puberty in sheep is initiated by a complex neuroendocrine interplay which cascades into an increased LH pulsatility at this time. Blood-borne amino acids have been proposed as metabolic signals for the stimulation of GnRH/LH secretion, a mandatory requirement for pubertal onset. In previous experiments we have demonstrated that a 1 h infusion of L-arginine (ARG) was capable of stimulating the LH secretion in prepubertal ewes. The aim of the present study was to further examine the effect of an intravenous infusion of ARG on LH secretion. Prepubertal ewes were infused for 6 h with 15 (Group ARG15, n = 5) or 30 g (Group ARG30, n = 5) of L-ARG dissolved in 500 mL saline (pH 7.4), while saline was administered as control (Group S, n = 5). Since ARG is metabolized to ornithine (ORN), equimolar doses of L-ORN were additionally tested (Group ORN12 and ORN24, n = 5, respectively). Blood samples were obtained at 15 minute intervals during and after experimental infusions to characterize the LH pulsatile secretion. The resulting hormone data arrays were searched for significant fluctuations by the PULSAR program. The LH pulse frequency was found to be higher in groups of ARG treated than in saline or ORN infused sheep during the 6-h infusion period: 5.6 +/- 1.0 (ARG15) vs. 5.0 +/- 0.5 (ARG30) vs. 2.0 +/- 0.9 (S, p < 0.01) vs. 3.4 +/- 0.9 (ORN12) vs. 3.4 +/- 0.9 pulses/6 h (ORN24, p < 0.05). The total number of pulses was higher in ARG infused lambs than in saline or ORN infused animals: 11.2 +/- 1.2 (ARG15) vs. 10 +/- 1.1 (ARG30) vs. 13.8 +/- 1.4 (S) vs. 5.8 +/- 1.7 (ORN12) vs. 5.8 +/- 2.0 pulses/12h (ORN24), respectively. The LH mean secretion was comparable during both 6-h periods in all groups. Results of our experiments demonstrate increased LH pulse frequencies during ARG infusions, suggesting an action of ARG to stimulate hypothalamic GnRH release. Thus, ARG may be a critical determinant for enhanced LH pulsatility as a prerequirement for the onset of puberty in the sheep.
Asunto(s)
Arginina/farmacología , Hormona Luteinizante/metabolismo , Ornitina/farmacología , Análisis de Varianza , Animales , Arginina/administración & dosificación , Femenino , Infusiones Intravenosas , Cinética , Hormona Luteinizante/sangre , Ornitina/administración & dosificación , Valores de Referencia , Maduración Sexual , Ovinos , Factores de TiempoRESUMEN
Photography is important in everyday dentistry. Using acquired skill it is possible for anyone to produce a reasonable clinical photograph. To obtain good results it is necessary to be aware of the controlling factors: the lens, camera, lighting direction, length of exposure and the type and color balance of the film. The following text should help the clinician to choose equipment best suited to his/her practice.