RESUMEN
PURPOSE OF THE STUDY: The prevalence of vitamin D deficiency in pediatric populations is high. In the present study we analyzed associations between vitamin D therapy and pain, mobility, fatigue, and daily functioning in children with musculoskeletal/orthopedic conditions suffering from chronic and recurrent pain, but also diagnosed with vitamin D deficiency. MATERIAL AND METHODS: Children with different musculoskeletal/orthopedic conditions and vitamin D deficiency were prescribed to receive vitamin D over 6 months. Thirty-five children (18 males; age 10.48 ± 3.87 years) completed a 6-month follow-up. Self- and parent/proxy rating scales were used to evaluate pain, movement, fatigue, and daily functioning. RESULTS: At a six-month follow-up assessment involving child- and parent-reported scores, worst pain intensity significantly decreased (p ≤ 0.03) after vitamin D therapy, as well as functioning problems related to pain (p ≤ 0.01). The children reported better movement and balance with less fatigue. The parents reported better functioning in everyday activities of their children. CONCLUSION: This pilot study showed that vitamin D therapy possibly reduces pain intensity and improves mobility and daily functioning in children with musculoskeletal/orthopedic disorders, chronic recurrent pain, and vitamin D deficiency. Further follow-up and randomized studies are required in order to assess the validity of clinical recommendations.
Asunto(s)
Dolor Musculoesquelético/diagnóstico , Dolor Musculoesquelético/tratamiento farmacológico , Dimensión del Dolor/efectos de los fármacos , Deficiencia de Vitamina D/diagnóstico , Deficiencia de Vitamina D/tratamiento farmacológico , Vitamina D/uso terapéutico , Adolescente , Niño , Fatiga/tratamiento farmacológico , Femenino , Estudios de Seguimiento , Humanos , Masculino , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/tratamiento farmacológico , Dolor Musculoesquelético/sangre , Proyectos Piloto , Prevalencia , Vitamina D/análogos & derivados , Vitamina D/sangre , Deficiencia de Vitamina D/sangreRESUMEN
Rhabdomyosarcoma (RMS) is a highly malignant cancer. Over the last two decades, prognosis for RMS patients has significantly improved, with the exception of those in the high-risk group. In order to identify new prognostic factors, we investigated the expression of nestin in RMS cells and its correlation with clinicopathological features and patient outcome. The analysis of overall survival for all patients (N = 30) revealed 1-, 2-, 3-, 4-, and 5-year survival rates of 93.3, 83.3, 66.7, 63.3, and 63.3%, respectively. Nestin overexpression significantly correlated with survival (P = 0.044). Survival of patients with ≤ 50% nestin-positive cells was 90, 70, and 40% after 1, 2, and 3 years, respectively, and remained unchanged until the end of the investigation period. The study group composed of patients exhibiting nestin expression in >50% of cells showed 1-, 2-, 3-, and 4-year survival rates of 95, 90, 80, and 75%, respectively, remaining stable at 75% for the fifth year of observation. A nestin-positive expression rate lower than 50% was observed more frequently in older patients (43.60 ± 27.58 years; P = 0.028). In addition, higher rates of nestin expression were observed in most embryonal RMS specimens and low-grade tumors, in early stages of the disease, and among younger patients. Our results lead us to propose nestin as possible positive prognostic factor in RMS.
Asunto(s)
Biomarcadores de Tumor/biosíntesis , Nestina/biosíntesis , Pronóstico , Rabdomiosarcoma/genética , Adolescente , Adulto , Anciano , Biomarcadores de Tumor/genética , Niño , Preescolar , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Lactante , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Nestina/genética , Rabdomiosarcoma/patologíaRESUMEN
The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g(-1) of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu(2+) ions but it is very low for Fe(2+) ions, not exceeding 10%.
Asunto(s)
Iones , Metales Pesados/química , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Metales , Tamaño de la Partícula , Protones , Espectrofotometría Atómica , Espectrofotometría Ultravioleta/métodos , Factores de Tiempo , Árboles , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , MaderaAsunto(s)
Ecotoxicología/métodos , Genómica/métodos , Metabolómica/métodos , Proteómica/métodos , Proyectos de Investigación , Toxicogenética/métodos , Exposición a Riesgos Ambientales , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/toxicidad , Contaminación Química del Agua/prevención & controlRESUMEN
In this study we compared the effects of PCB126 and PCB153 on adult rat testicular androgenesis and the status of antioxidant enzymes in the interstitial cell compartment 96h after local intratesticular application. Obtained results indicated PCB126-induced inhibition of conversion of progesterone (P) and Δ(4)-androstenedione (A(4)) to testosterone (T), and stimulation of conversion of P to T induced by PCB153, while combined application had no effect. Activities of antioxidant enzymes were unchanged, except of decreased activity of SOD in PCB126-treated group. In parallel experiments, adult purified Leydig cells challenged with PCB congeners were incubated for 2h in the presence of corresponding steroid substrates. Results demonstrated that in the presence of subsaturating substrate concentrations PCB126 induced inhibition of conversion of P and A(4) to T at nM to µM doses, while PCB153 caused stimulation at nM concentrations. Further studies should indicate possible mechanism(s) of modulation of androgenesis by tested PCB congeners.
Asunto(s)
Cromatografía de Gases/métodos , Contaminantes Ambientales/análisis , Sedimentos Geológicos/química , Bifenilos Policlorados/análisis , Suelo/análisis , Animales , Bioensayo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cromatografía de Gases/instrumentación , Croacia , Citocromo P-450 CYP1A1/metabolismo , Monitoreo del Ambiente/métodos , Contaminantes Ambientales/toxicidad , Hepatocitos/efectos de los fármacos , Hepatocitos/enzimología , Bifenilos Policlorados/toxicidad , RatasRESUMEN
Starting from a 16-oximino derivative of 5-androstene the newly-synthesized 16-oximino-17-hydroxy-17-substituted derivatives 2-4 gave by the Beckmann fragmentation reaction the corresponding D-seco derivatives 6-9. Besides, in the case of the 17-hydroxy-17-methyl-16-oximino derivative 2, as a result of the rearrangement, the hydrolysis product 5 of the 16-oximino group with the opposite configuration at the C-17 was obtained. By the Oppenauer oxidation and/or by dehydration of 7 with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), the corresponding derivatives 12, 13, and 14 were obtained. The structures of 6 and 12 were unambiguously proved by the appropriate X-ray structural analysis. Kinetic analysis for anti-aromatase activity showed that compound 12 expressed the highest inhibition in the denucleated rat ovarian fraction in comparison to other androstene derivatives (IC(50) was 0.42 microM). In comparison to aminoglutethimide (AG) activity, it was 3.5 times lower. The inhibition was competitive, with K(i) of 0.27 microM. Introduction of additional units of unsaturation (compounds 13 and 14) in D-seco derivatives did not increase anti-aromatase activity.
Asunto(s)
Androstanos/química , Androstanos/farmacología , Inhibidores de la Aromatasa , Animales , Benzoquinonas/farmacología , Unión Competitiva , Cristalografía por Rayos X , Femenino , Hidrólisis , Concentración 50 Inhibidora , Cinética , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Ratas , Ratas WistarRESUMEN
Polychlorinated biphenyl (PCB)-based transformer fluids belong to a class of environmentally persistent mixtures with known toxic effects. Here, we studied the acute effects of Askarel (which contains Aroclor 1260) and two substitute transformer fluids (the silicone oil-based DC561 and the mineral oil-based ENOL C) on rat testicular steroidogenesis. Single intraperitoneal (ip; 10 mg/kg body weight) or bilateral intratesticular (itt; 25 microg/testis) injections of Askarel markedly decreased serum androgen levels 24 hr after administration. In acute testicular cultures from these animals, chorionic gonadotropin-stimulated progesterone and androgen productions were severely attenuated. When itt was injected or added in vitro, Askarel inhibited 3ss-hydroxysteroid dehydrogenase (3ssHSD), stimulated 17[alpha]-hydroxylase/lyase (P450c17), and did not affect 17ss-hydroxysteroid dehydrogenase in testicular postmitochondrial fractions. The ip-injected Askarel did not affect 3ssHSD, but inhibited P450c17, suggesting that a more intensive metabolism of peripherally injected Askarel reduces the circulating levels of active ingredients below the threshold needed for inhibition of 3ssHSD and generates a derivative that inhibits P450c17. In contrast to Askarel, itt-injection (25 microg/testis) of DC561 and ENOL C did not affect in vivo and in vitro steroidogenesis. These findings show the acute effects of Askarel, but not silicone and mineral oils, on testicular steroidogenesis.
Asunto(s)
Arocloros/efectos adversos , Bifenilos Policlorados/efectos adversos , Hormonas Testiculares/biosíntesis , Testículo/fisiología , Animales , Técnicas de Cultivo , Infusiones Parenterales , Masculino , Ratas , Ratas Wistar , Testículo/efectos de los fármacosRESUMEN
Polychlorinated biphenyls (PCBs) are complex mixtures of congeners that exhibit carcinogenic and toxicant activities in a variety of mammalian tissues. Here, we studied the acute in vivo and in vitro effects of a commercially used PCB product, Aroclor 1248 (A1248), a mixture of tri-, tetra-, and pentachloro congeners. Single intraperitoneal (i.p.) or bilateral intratesticular (i.t.) injections of A1248 decreased serum androgen levels in both groups 24 h after injection. Chorionic gonadotropin-stimulated androgen production by acute testicular cultures from both groups was also reduced, and progesterone production was attenuated in cultures from i.t.-treated animals. The capacity of the postmitochondrial fractions from testes of i.t.-treated animals to convert pregnenolone to progesterone and progesterone to testosterone was reduced as well. In vitro studies revealed that a 10- to 15-min exposure of postmitochondrial testicular fractions and intact interstitial cells from normal animals to A1248 in a subnanomolar concentration range was sufficient to attenuate the conversion of pregnenolone to progesterone and progesterone to testosterone. At micromolar concentrations, A1248 added in vitro also inhibited the conversion of Delta(4)-androstendione to testosterone without affecting the viability of interstitial cells. These results indicate that A1248 down-regulates the testicular androgenesis by an acute inhibition of 3beta-hydroxysteroid dehydrogenase, 17alpha-hydroxylase/lyase, and 17beta-hydroxysteroid dehydrogenase activities.
Asunto(s)
Andrógenos/biosíntesis , Arocloros/farmacología , Testículo/efectos de los fármacos , Testículo/metabolismo , 17-Hidroxiesteroide Deshidrogenasas/antagonistas & inhibidores , 3-Hidroxiesteroide Deshidrogenasas/antagonistas & inhibidores , Androstenodiona/metabolismo , Animales , Gonadotropina Coriónica/farmacología , Dihidrotestosterona/sangre , Inhibidores Enzimáticos/farmacología , Masculino , Pregnenolona/metabolismo , Progesterona/metabolismo , Ratas , Ratas Wistar , Esteroide 17-alfa-Hidroxilasa/antagonistas & inhibidores , Testosterona/sangre , Testosterona/metabolismoRESUMEN
The messenger role of nitric oxide (NO) in immobilization stress-induced inhibition of testicular steroidogenesis has been previously suggested. In accord with this, here, we show that the intratesticular injection of isosorbide dinitrate (ISDN; 2x2.5 mg/testis), an NO donor, mimicked the action of stress on serum testosterone concentrations and hCG-stimulated testosterone production in rat testicular tissue. When added in vitro, ISDN inhibited testicular 3beta-hydroxysteroid dehydrogenase and 17alpha-hydroxylase/lyase. Immobilization stress and injections of ISDN also decreased the activity of catalase, glutathione peroxidase, glutathione transferase, and glutathione reductase in the interstitial compartment of testis. When stressed rats were treated concomitantly with bilateral intratesticular injections of N(omega)-nitro-L-arginine methyl ester, a non-selective NOS inhibitor (2x600 microg/testis), the activities of antioxidative enzymes, as well as serum testosterone concentration, were partially normalized. These results indicate that stress-induced stimulation of the testicular NO signalling pathway leads to inhibition of both steroidogenic and antioxidant enzymes.
Asunto(s)
Antioxidantes/metabolismo , Óxido Nítrico/metabolismo , Esteroides/biosíntesis , Estrés Fisiológico/metabolismo , Testículo/metabolismo , Animales , Catalasa/antagonistas & inhibidores , Gonadotropina Coriónica/farmacología , Inhibidores Enzimáticos/farmacología , Glutatión Peroxidasa/antagonistas & inhibidores , Glutatión Reductasa/antagonistas & inhibidores , Glutatión Transferasa/antagonistas & inhibidores , Técnicas In Vitro , Dinitrato de Isosorbide/farmacología , Masculino , NG-Nitroarginina Metil Éster/farmacología , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Ratas , Ratas Wistar , Testículo/efectos de los fármacos , Testosterona/biosíntesis , Testosterona/sangreRESUMEN
The immobilization stress induces an acute inhibition of testicular steroidogenesis that is mediated by the nitric oxide (NO) signaling pathway. Here we compared the effects of 2-h immobilization stress on in vivo and in vitro rat steroidogenesis at two time points, 0 h and 6 h after the end of the stress session. As expected, serum androgens and human chorionic gonadotropin (hCG)-stimulated progesterone and testosterone production by testicular tissue were inhibited at 0 h, and also at the 6-h time point. Both the acute and sustained inhibitions of in vitro steroidogenesis were accompanied by a significant increase in nitrite, a stable oxidation product of NO. To clarify which subtype of NO synthase (NOS) (constitutive (cNOS) or inducible (iNOS)) participates in down-regulation of testicular steroidogenesis, aminoguanidine hydrochloride (AG), a selective iNOS inhibitor, was employed. Intratesticular injection of AG prevented the sustained, but not the acute, stress-induced decrease in serum testosterone. When added in vitro, it also prevented the sustained decrease in steroid production and increase in nitrite production by testicular tissue, both in a dose-dependent manner and with EC microM. Furthermore, AG added in vivo and in vitro effectively blocked the sustained decrease in 3beta-hydroxysteroid dehydrogenase (3betaHSD) and 17alpha-hydroxylase/C17-20 lyase (P450c17) activities. In all concentrations employed, AG did not affect serum androgens and in vitro steroid and nitrite production in unstressed animals. These results indicate that the NO signaling pathway participates in acute and sustained stress-induced down-regulation of testicular steroidogenesis, presumably through its direct action on 3betaHSD and P450c17. The acute NO production is controlled by cNOS and the sustained production of this messenger is controlled by iNOS.
Asunto(s)
Óxido Nítrico Sintasa/metabolismo , Transducción de Señal , Estrés Psicológico/metabolismo , Testículo/efectos de los fármacos , Testosterona/metabolismo , Animales , Dihidrotestosterona/metabolismo , Inhibidores Enzimáticos/farmacología , Guanidinas/farmacología , Masculino , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico Sintasa de Tipo III , Nitritos/metabolismo , Progesterona/metabolismo , Ratas , Ratas Wistar , Restricción Física , Estadísticas no Paramétricas , Testículo/metabolismo , Factores de TiempoRESUMEN
Previous studies indicate that acute immobilization stress (IMO; 2 h) impaired testicular steroidogenesis primarily at the testicular level decreasing the activity of certain steroidogenic enzymes. In the present study unstressed rats as well as IMO rats (2 h) were treated by intratesticular injection of naltrexone methobromide (NMB; peripheral opioid receptor antagonist; 36 microg/testis) or vehicle at the beginning of and at 1 h of the IMO period. In IMO rats the activity of P450c17 was significantly reduced as well as the activity of NADPH-P450 reductase (which catalyzes the transfer of electrons from NADPH to cytochrome P450), while the activity of NADH-b5 reductase was not affected. Present data confirmed previous results that acute IMO reduced testicular P450c17 activity and implicate that decreased activity of NADPH-P450 reductase could be responsible for the inhibition of P450c17 under IMO conditions, while NADH-b5 reductase is probably not involved. NMB treatment antagonized the inhibitory effect of IMO on P450c17 and NADPH-P450 reductase activities. Such results put forward the implication that endogenous opioid peptides are involved in mediating the inhibitory effect of IMO on testicular steroidogenesis, and allow the speculation that NADPH-P450 reductase could be a possible site of such an inhibition.
Asunto(s)
Células Intersticiales del Testículo/enzimología , NADH NADPH Oxidorreductasas/metabolismo , Naltrexona/análogos & derivados , Estrés Fisiológico , Testículo/efectos de los fármacos , 17-alfa-Hidroxiprogesterona/análogos & derivados , 17-alfa-Hidroxiprogesterona/metabolismo , Androstenodiona/metabolismo , Animales , Reductasas del Citocromo/metabolismo , Citocromo-B(5) Reductasa , Masculino , NADPH-Ferrihemoproteína Reductasa , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Progesterona/metabolismo , Compuestos de Amonio Cuaternario , Ratas , Ratas Wistar , Esteroide 17-alfa-Hidroxilasa/metabolismo , Esteroides/metabolismo , Testosterona/metabolismoRESUMEN
The participation of the nitric oxide (NO) pathway in downregulation of testicular steroidogenesis in normal and stressed rats was investigated both in vivo and in vitro. In Leydig cells from normal animals, isosorbide dinitrate, an NO donor, decreased the human chorionic gonadotropin (CG)-stimulated and progesterone-derived androgen production. Also, the intratesticular injection of a precursor of NO, arginine (10 mg/testis), transiently decreased serum androgen levels and inhibited human CG-stimulated androgen production in acute testicular cultures. These effects were eliminated in rats cotreated with Nomega-nitro-L-arginine methyl ester (L-NAME) (2 X 600 microg/each testis). Acute immobilization stress (2 h) decreased serum androgen levels and inhibited human CG-stimulated androgen production in vitro. These effects were accompanied by a significant increase in nitrite, a stable oxidation product of NO, in testicular cultures. Bilateral intratesticular injection of L-NAME prevented the stress-induced decrease of human CG-stimulated androgen production, and significantly reduced the nitrite levels. These results implicate NO in normal and stress-impaired testicular steroidogenesis.
Asunto(s)
Óxido Nítrico/fisiología , Esteroides/biosíntesis , Estrés Psicológico/metabolismo , Testículo/metabolismo , Animales , Arginina/farmacología , Inhibidores Enzimáticos/farmacología , Inmovilización , Masculino , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Nitritos/sangre , Ratas , Ratas Wistar , Testículo/efectos de los fármacos , Testosterona/sangreRESUMEN
From September 1991 to December 1992, during the war in Croatia, the General Hospital in Slavonski Brod served as an evacuation centre. During that period 197 patients with war-related penetrating craniocerebral injuries were admitted. They were analyzed according to wound characteristics, operability, mortality, operative and post-operative complications, and their condition after hospital discharge and follow-up. A less aggressive surgical approach was accepted in our surgical strategy, recommended in recent studies, followed by an aggressive intensive management. All patients received antibiotics ("war scheme") and anticonvulsants. Early results of treatment do not differ significantly from other recent studies (Vietnam, Israel) in respect to both mortality and complications. Follow-up was difficult. Most of the patients were Bosnia and Herzegovina citizens who were refugees and banished to foreign countries; thus their addresses were unknown. They are consequently lost to follow-up. A less aggressive surgical approach proved to be justified. Routine use of antibiotics and anticonvulsants lowered the infection rate and early seizure incidence to an acceptable level. Late seizure incidence is similar to those previously reported.
Asunto(s)
Lesiones Encefálicas/cirugía , Guerra , Heridas Penetrantes/cirugía , Adolescente , Adulto , Antibacterianos/uso terapéutico , Anticonvulsivantes/uso terapéutico , Lesiones Encefálicas/diagnóstico por imagen , Lesiones Encefálicas/mortalidad , Croacia/epidemiología , Desbridamiento , Epilepsia/etiología , Epilepsia/prevención & control , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Tomografía Computarizada por Rayos X , Heridas Penetrantes/diagnóstico por imagen , Heridas Penetrantes/mortalidadRESUMEN
The present study examined the effects of naloxone (N) and naltrexone-methobromide (NMB; an opioid receptor antagonist that does not cross the blood-brain barrier) on testicular steroidogenesis during acute immobilization stress (IMO; 2 h) in adult rats. Unstressed rats as well as IMO rats were treated by unilateral intratesticular injection of N (20 micrograms/testis), NMB (36 micrograms/testis), or vehicle at the beginning of and at 1 h of the IMO period. In IMO rats serum T levels were significantly reduced, while serum luteinizing hormone levels were not affected. N and NMB normalized serum T levels in IMO rats and had no effects in controls. In IMO rats the activities of 3 beta-hydroxysteroid dehydrogenase (HSD) and P450(17 alpha, lyase) were significantly reduced, while the activity of 17 beta-HSD was not affected. N and NMB antagonized the inhibitory effect of IMO on 3 beta-HSD and P450(17 alpha, lyase) but did not alter enzyme activity in freely moving rats. Acute IMO decreased basal and human chorionic gonadotropin-stimulated androgen production by hemitestis preparation, but N (10(-4) M) added directly to the incubation medium blocked the decrease and had no effect on testes from freely moving control rats. These results support the conclusion that endogenous opioid peptides are potentially important paracrine regulators of testicular steroidogenesis under stress conditions.
Asunto(s)
Naloxona/farmacología , Naltrexona/análogos & derivados , Antagonistas de Narcóticos/farmacología , Estrés Fisiológico/metabolismo , Testículo/efectos de los fármacos , Testículo/metabolismo , 3-Hidroxiesteroide Deshidrogenasas/metabolismo , Animales , Inyecciones , Masculino , Naloxona/administración & dosificación , Naltrexona/administración & dosificación , Naltrexona/farmacología , Compuestos de Amonio Cuaternario , Ratas , Ratas Wistar , Restricción Física , Testosterona/biosíntesis , Testosterona/sangreRESUMEN
In rats, acute immobilization (IMO) stress (2 h) induced a fall in the serum androgen concentrations (T+DHT) without detectable changes in serum luteinizing hormone (LH) values. In vitro studies, using a suspension of Leydig cells from adult rat testis, demonstrated that acute stress inhibited conversion of progesterone (P) or 17hydroxyprogesterone (17OHP) to T while conversion of androstendione (delta 4 A) was not affected. Acute IMO reduced activity of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and decreased basal and hCG-stimulated progesterone and androgen production. Chronic IMO stress (2 h daily for 10 days) induced a decrease in serum androgen level with decline in serum LH values. In vitro, hCG-stimulated progesterone and androgen production by suspension of Leydig cells, as well as conversion of P and 17OHP to T were not significantly altered. Our data demonstrates that acute IMO stress impaired testicular steroidogenesis primarily at the testicular level (decreasing the activity of certain enzymes), while chronic IMO stress exerts the effect mainly on the hypothalamic-pituitary axis; reduced serum LH levels elicit a decrease in serum androgen levels.
Asunto(s)
Células Intersticiales del Testículo/metabolismo , Esteroides/biosíntesis , Animales , Células Cultivadas , Inmovilización , Células Intersticiales del Testículo/enzimología , Masculino , Ratas , Esteroides/sangre , Estrés FisiológicoRESUMEN
The effects of PCBs (mixture of 2, 3, 4, 5-tetra; 2, 2', 4, 5, 5'-penta; 2, 2', 3, 3', 6, 6'-hexa and 2, 2', 3, 3', 4, 4', 5, 5'-octa congeners) on androgen production were investigated by suspension of Leydig cells from adult rat testis. hCG-stimulated androgen production was significantly inhibited by PCBs while progesterone level was not affected. Progesterone supported testosterone production was also decreased by PCBs, while conversion of androstenedione to testosterone was unchanged. These results suggest that the activity of microsomal enzyme C21 side-chain cleavage P450 was decreased by PCB treatment of Leydig cells in vitro.
Asunto(s)
Andrógenos/biosíntesis , Células Intersticiales del Testículo/efectos de los fármacos , Células Intersticiales del Testículo/metabolismo , Bifenilos Policlorados/toxicidad , Androstenodiona/metabolismo , Animales , Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/antagonistas & inhibidores , Gonadotropina Coriónica/farmacología , Contaminantes Ambientales/toxicidad , Técnicas In Vitro , Masculino , Progesterona/metabolismo , Ratas , Ratas Wistar , Testosterona/biosíntesisRESUMEN
The present in vitro studies using a suspension of Leydig cells from adult rat testis demonstrated that bromocriptine (BR, 2 x 10(-5)M) inhibits hCG-stimulated testosterone production (in the presence of submaximal and maximal doses of hCG), while basal production was unaffected. When the cells were exposed to 8-bromo-cAMP either in the presence or absence of hCG, the inhibitory effect of BR was not reversed. In intact cells, BR inhibited conversion of progesterone and 17-hydroxy-progesterone to testosterone while conversion of androstenedione was not affected. Incubation of homogenates of Leydig cells in the presence of limiting NADPH concentrations (< or = 0.1 mM) resulted in significant BR-induced inhibition of conversion of progesterone (10 microM) to testosterone, while in the presence of "high" concentrations of NADPH (> or = 0.5 mM) BR was without effect. Present results suggest that BR inhibits androgen production at the level of the microsomal enzymes 17 alpha-hydroxylase and/or 17,20-lyase. The inhibitory effect of BR using homogenates of Leydig cells was evident only in the presence of limiting NADPH concentrations that suggests a competitive-like pattern of inhibition, but mechanisms by which BR decreases activity of microsomal enzymes remain to be determined.
Asunto(s)
Aldehído-Liasas/antagonistas & inhibidores , Andrógenos/metabolismo , Bromocriptina/farmacología , Inhibidores Enzimáticos del Citocromo P-450 , Células Intersticiales del Testículo/enzimología , Esteroide 17-alfa-Hidroxilasa/antagonistas & inhibidores , Animales , Gonadotropina Coriónica/farmacología , Cinética , Células Intersticiales del Testículo/efectos de los fármacos , Células Intersticiales del Testículo/metabolismo , Masculino , Ratas , Ratas Wistar , Testosterona/metabolismoRESUMEN
Developing male rats were treated chronically with bromocriptine (BR, 3 mg/kg b.w. daily) to maintain severe hypoprolactinaemia throughout postnatal development. This treatment induced a precocious increase in Leydig cell numbers per testis and caused substantial, but age-dependent, modifications of the androgenic responsiveness of incubated hemi-testis preparations to stimulation with hCG. Most conspicuous were: (i) a decrease in sensitivity of the testis to hCG at the approach of adult age (due presumably to reduced responsiveness of the Leydig cells), and (ii) a precocious increase in the steroidogenic maximum of the testis at peripubertal age. This probably resulted from the precocious increase in Leydig cell numbers, which was able to mask the negative consequences of reduced androgenic capacity per Leydig cell. The precocious increase in number of Leydig cells induced by hypoprolactinaemia could have resulted from facilitation of the proliferative action of the high prepubertal LH levels on Leydig cell numbers. There were no clear-cut indications for an important effect of BR-induced changes in LH levels, or of a direct effect of BR on the testis.
Asunto(s)
Andrógenos/metabolismo , Gonadotropina Coriónica/farmacología , Prolactina/sangre , Testículo/efectos de los fármacos , Animales , Bromocriptina/farmacología , Masculino , Ratas , Ratas Endogámicas , Maduración SexualRESUMEN
Contrary to earlier views on the inability of naloxone to affect androgen variables by way of general circulation, systemically applied naloxone (2.5 mg/kg body weight, single i.p. or i.v. injection) has been shown to rapidly induce (within an hour) a significant fall (-35.7% on the average) of the concentration of serum androgen (testosterone and dihydrotestosterone; (T + DHT) in peripubertal rats (51-58 days old). Such a response to the opiate antagonist was absent, however, in low-androgen prepubertal animals (37-44 days old) and in those among peripubertal rats which still showed subcritical initial levels of androgen in circulation (less than 1.5 ng/ml; experiments with repeated blood sampling in catheterized animals). In peripubertal rats naloxone was also shown to induce a significant decrease (-36%) in basal in vitro androgen production by testes removed 15 or 30 min following the intraperitoneal administration of the opiate antagonist. Such an inhibitory effect on basal steroidogenesis has not been observed in control multiple-dose experiments in which incubated testes from naloxone-naive rats have been directly challenged with naloxone; on the contrary, enhancing direct effects were recorded, but only with the highest concentration of naloxone tested (10(-4) M). The possibility thus remains open that indirect inhibitory effects of injected naloxone may be operational in intact animals. Hypoprolactinemia, known to interfere in an age-dependent manner with the responsiveness of Leyding cells to luteinizing hormone (LH), may be of particular relevance.(ABSTRACT TRUNCATED AT 250 WORDS)