RESUMEN
Previous studies have shown that both the signal transducer and activator of transcription 5 (STAT5) and the CCAAT enhancer binding proteins (C/EBPs) are involved in the regulation of casein gene expression by mammary epithelial cells. Prolactin (Prl) activation of STAT5 is necessary for casein gene expression. The extracellular matrix (ECM) regulates also casein gene expression. Here, we have investigated whether ECM regulates C/EBPs activity in primary rabbit mammary epithelial cells. Isolated primary mammary cells were cultured on plastic or on floating collagen I gel. Prolactin induced alphas 1-casein gene expression when cells were cultured on collagen but not on plastic. It is noteworthy that activated STAT5 was detected in both culture conditions. Several STAT5 isoforms (STAT5a, STAT5b, and other STAT5 related isoforms, some with lower molecular weight than the full-length STAT5a and STAT5b) were detected under the different culture conditions. However, their presence was not related to the expression of alphas 1-casein gene. The binding of nuclear factors to a C/EBP specific binding site and the protein level of C/EBPbeta differed in cells cultured on plastic or on collagen but these parameters were not modified by Prl. This suggests that C/EBP binding activity was regulated by ECM and not by Prl. Interestingly, these modifications were correlated to the expression of the alphas 1-casein gene. Hence, the activation of the alphas 1-casein gene expression depends on two independent signals, one delivered by Prl via the activation of STAT5, the other delivered by ECM via C/EBP.
Asunto(s)
Mama/metabolismo , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Caseínas/genética , Colágeno/metabolismo , Matriz Extracelular/metabolismo , Regulación de la Expresión Génica , Proteínas de la Leche , Animales , Apoptosis , Mama/citología , Mama/efectos de los fármacos , Técnicas de Cultivo de Célula/métodos , Células Cultivadas , Citosol/metabolismo , ADN/genética , ADN/metabolismo , Proteínas de Unión al ADN/metabolismo , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Plásticos/metabolismo , Prolactina/farmacología , Unión Proteica/efectos de los fármacos , Isoformas de Proteínas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Conejos , Elementos de Respuesta/genética , Factor de Transcripción STAT5 , Transactivadores/metabolismoRESUMEN
The origins and routes of the postganglionic sympathetic nerve supply to the upper and lower uterus and to the cervix were investigated in the rat by using denervation procedures combined with immunohistochemistry and retrograde tracing. The sympathetic nerve fibers of the upper part of the uterus arise from the ovarian plexus nerve. They mainly originate (90%) from neurons of the suprarenal ganglia (SRG) and of the T10 to L3 ganglia of the paravertebral sympathetic chain. Fluoro-Gold injections into different regions of the upper uterus showed that the SRG neurons mainly provide innervation to the tubal extremity (52%) rather than to the uterine portion below this area (26%). Very few neurons of the celiac ganglion or the aorticorenal ganglia participated in this innervation. Most of the sympathetic innervation of the lower uterus and the cervix (90%) originates from neurons of the paravertebral ganglia T13 to S2, principally at the L2-L4 levels. By using immunocytochemistry, we show that very few tyrosine hydroxylase-positive neurons of the pelvic plexus project to these areas, where they represent only 3% of the sympathetic nerve supply. Again, very few neurons of the inferior mesenteric ganglion (IMG) supply the lower uterus and the cervix. The comparison between retrograde tracing experiments in intact animals and after the removal of the IMG shows that very few sympathetic postganglionic axons from the paravertebral chain pass through the IMG to reach the lower uterus and the cervix. In contrast, these axons mainly project to splanchnic nerves bypassing the IMG to connect with the hypogastric nerves. In addition, some axons supplying the lower uterus follow the superior vesical arteries and then reach the organ. Taken together, these results show that the upper region of the uterus receives a sympathetic innervation that is different in origin and route from that of the lower uterus and the cervix. Such a marked region-specific innervation suggests that nerve control of the myometrial activity may be functionally different between the oviduct and the cervical ends of the uterus.
Asunto(s)
Cuello del Útero/inervación , Ganglios Simpáticos/anatomía & histología , Ratas Sprague-Dawley/anatomía & histología , Estilbamidinas , Animales , Femenino , Colorantes Fluorescentes , Ganglios Simpáticos/química , Ganglios Simpáticos/enzimología , Norepinefrina/análisis , Pelvis/inervación , Ratas , Simpatectomía , Fibras Simpáticas Posganglionares/química , Fibras Simpáticas Posganglionares/enzimología , Simpatomiméticos/análisis , Tirosina 3-Monooxigenasa/análisisRESUMEN
Expression and androgen regulation of the gene for neuronal nitric oxide synthase (NOS I) were examined in neurons of the major pelvic ganglia in male rats. Some of these postganglionic neurons innervate the penis and produce nitric oxide, which is believed to play a major role in penile erection. Rats were either castrated or sham operated and implanted with SILASTIC brand capsules filled with powdered testosterone (T) or 5alpha-dihydrotestosterone (5alphaDHT) or left empty. After 4 days, the number of neurons intensely stained for NADPH-diaphorase as well as those giving a NOS I signal in in situ hybridization experiments increased in castrated rats treated with testosterone by 31% and 42%, respectively, relative to those in untreated castrated rats. This suggests that the increase in NADPH-diaphorase activity resulted from enzyme synthesis and was due to a modification of NOS I messenger RNA (mRNA) accumulation. After 7 days, Northern blot analysis showed that castration produced a decrease in the amount of NOS I mRNA relative to that of ribosomal RNA. This decrease was almost prevented by T treatment. No significant differences were observed by reverse transcriptase-PCR between 7-day and 28-day treatments. However, in 7-day castrated rats treated with 5alphaDHT, NOS I signals relative to those of hypoxanthine phosphoribosyltransferase, taken as reference, were significantly higher than those in castrated rats and resembled those in sham-castrated rats, suggesting that 5alphaDHT was probably more potent than testosterone in preventing the decrease in NOS I mRNA levels elicited by castration. These results show that NOS I can be positively regulated by androgens and are consistent with the suggestion that these steroids play a role in the physiological processes of penile erection.
Asunto(s)
Andrógenos/farmacología , Ganglios Autónomos/citología , Plexo Hipogástrico/citología , Neuronas/enzimología , Óxido Nítrico Sintasa/genética , ARN Mensajero/análisis , Animales , Secuencia de Bases , Northern Blotting , Cartilla de ADN/análisis , Cartilla de ADN/química , Cartilla de ADN/genética , Dihidrotestosterona/farmacología , Ganglios Autónomos/química , Ganglios Autónomos/enzimología , Regulación Enzimológica de la Expresión Génica , Plexo Hipogástrico/química , Plexo Hipogástrico/enzimología , Hibridación in Situ , Masculino , NADPH Deshidrogenasa/análisis , Neuronas/metabolismo , Orquiectomía , Reacción en Cadena de la Polimerasa , ARN Mensajero/química , ARN Mensajero/genética , Ratas , Ratas Sprague-Dawley , Testosterona/farmacologíaRESUMEN
The post-partum secretion of LH, FSH and prolactin was monitored in 15 suckling and 6 non-suckling Préalpes du Sud ewes lambing during the breeding season by measuring plasma hormone concentrations daily at 6-h intervals and also weekly at 20-min intervals for 6 h from parturition to resumption of regular cyclic ovarian activity. There was a constant phenomenon in the resumption of normal patterns of FSH and LH secretion: there was a rise in FSH values culminating on average on Day 4 post partum and returning subsequently to values observed during the oestrous cycle, and concurrently an increase in the frequency and amplitude of LH pulses more progressive in suckling than in non-suckling ewes which led to an elevation of LH mean concentrations and occurrence of an LH surge. Since neither the FSH secretory pattern nor FSH mean values differed between suckling and non-suckling ewes, the results suggested that LH pulsatile pattern was a major limiting factor for the resumption of normal oestrous cycles. Before regular oestrous cycles resumed other changes in preovulatory LH surges also occurred: (i) they increased in duration and probably in amplitude; (ii) they were preceded by an acceleration in LH pulse frequency and a large decrease in FSH values as in normal cyclic ewes; and (iii) at least in non-suckling ewes they occurred concurrently with a prolactin surge.
Asunto(s)
Gonadotropinas Hipofisarias/sangre , Lactancia/sangre , Periodo Posparto/sangre , Ovinos/sangre , Animales , Estro/sangre , Femenino , Hormona Folículo Estimulante/sangre , Hormona Luteinizante/sangre , Embarazo , Prolactina/sangreRESUMEN
The antigenic properties of human prolactin (HPr) were studied using various methods of radio-immuno assay. The homologous system, the difficulty of which resides in the preparation of the tracer, easily permits measurement of physiological levels. In this systems, blood prolactin in the monkey, has an antigenicity comparable with that of human prolactin, whereas growth hormone and human chorionic somatotropin have feeble or nil antigenic relationship with HPr. Human, sheep and pig prolactins have variable antigenic cross-reactions depending on the immune serum used. These antigenic cross reactions may be applied to the isolation of amniotic prolactin Human blood prolactin has several components of different molecular weight, but antigenicity comparable with that of pituitary HPr.