RESUMEN
BACKGROUND: Identifying youth who may engage in future substance use could facilitate early identification of substance use disorder vulnerability. We aimed to identify biomarkers that predicted future substance use in psychiatrically un-well youth. METHOD: LASSO regression for variable selection was used to predict substance use 24.3 months after neuroimaging assessment in 73 behaviorally and emotionally dysregulated youth aged 13.9 (s.d. = 2.0) years, 30 female, from three clinical sites in the Longitudinal Assessment of Manic Symptoms (LAMS) study. Predictor variables included neural activity during a reward task, cortical thickness, and clinical and demographic variables. RESULTS: Future substance use was associated with higher left middle prefrontal cortex activity, lower left ventral anterior insula activity, thicker caudal anterior cingulate cortex, higher depression and lower mania scores, not using antipsychotic medication, more parental stress, older age. This combination of variables explained 60.4% of the variance in future substance use, and accurately classified 83.6%. CONCLUSIONS: These variables explained a large proportion of the variance, were useful classifiers of future substance use, and showed the value of combining multiple domains to provide a comprehensive understanding of substance use development. This may be a step toward identifying neural measures that can identify future substance use disorder risk, and act as targets for therapeutic interventions.
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Conducta del Adolescente/fisiología , Síntomas Afectivos/fisiopatología , Corteza Cerebral , Depresión/fisiopatología , Problema de Conducta , Recompensa , Trastornos Relacionados con Sustancias/diagnóstico , Adolescente , Corteza Cerebral/diagnóstico por imagen , Corteza Cerebral/fisiología , Corteza Cerebral/fisiopatología , Niño , Femenino , Estudios de Seguimiento , Humanos , Imagen por Resonancia Magnética , Masculino , Trastornos Relacionados con Sustancias/diagnóstico por imagen , Trastornos Relacionados con Sustancias/patología , Trastornos Relacionados con Sustancias/fisiopatologíaRESUMEN
Behavioral and emotional dysregulation in childhood may be understood as prodromal to adult psychopathology. Additionally, there is a critical need to identify biomarkers reflecting underlying neuropathological processes that predict clinical/behavioral outcomes in youth. We aimed to identify such biomarkers in youth with behavioral and emotional dysregulation in the Longitudinal Assessment of Manic Symptoms (LAMS) study. We examined neuroimaging measures of function and white matter in the whole brain using 80 youth aged 14.0 (s.d.=2.0) from three clinical sites. Linear regression using the LASSO (Least Absolute Shrinkage and Selection Operator) method for variable selection was used to predict severity of future behavioral and emotional dysregulation measured by the Parent General Behavior Inventory-10 Item Mania Scale (PGBI-10M)) at a mean of 14.2 months follow-up after neuroimaging assessment. Neuroimaging measures, together with near-scan PGBI-10M, a score of manic behaviors, depressive behaviors and sex, explained 28% of the variance in follow-up PGBI-10M. Neuroimaging measures alone, after accounting for other identified predictors, explained ~1/3 of the explained variance, in follow-up PGBI-10M. Specifically, greater bilateral cingulum length predicted lower PGBI-10M at follow-up. Greater functional connectivity in parietal-subcortical reward circuitry predicted greater PGBI-10M at follow-up. For the first time, data suggest that multimodal neuroimaging measures of underlying neuropathologic processes account for over a third of the explained variance in clinical outcome in a large sample of behaviorally and emotionally dysregulated youth. This may be an important first step toward identifying neurobiological measures with the potential to act as novel targets for early detection and future therapeutic interventions.
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Síntomas Afectivos/fisiopatología , Sustancia Blanca/fisiopatología , Adolescente , Síntomas Afectivos/genética , Trastorno Bipolar/diagnóstico , Encéfalo/fisiopatología , Niño , Emociones/fisiología , Femenino , Predicción/métodos , Humanos , Estudios Longitudinales , Masculino , Padres/psicología , Escalas de Valoración Psiquiátrica , Recompensa , Resultado del TratamientoRESUMEN
BACKGROUND: Offspring of parents with bipolar disorder (BD) (BO) are at higher risk of BD than offspring of parents with non-BD psychopathology (NBO), although both groups are at higher risk than offspring of psychiatrically healthy parents (HC) for other affective and psychiatric disorders. Abnormal functioning in reward circuitry has been demonstrated previously in individuals with BD. We aimed to determine whether activation and functional connectivity in this circuitry during risky decision-making differentiated BO, NBO and HC. METHOD: BO (n = 29; mean age = 13.8 years; 14 female), NBO (n = 28; mean age = 13.9 years; 12 female) and HC (n = 23; mean age = 13.7 years; 11 female) were scanned while performing a number-guessing reward task. Of the participants, 11 BO and 12 NBO had current non-BD psychopathology; five BO and four NBO were taking psychotropic medications. RESULTS: A 3 (group) × 2 (conditions: win-control/loss-control) analysis of variance revealed a main effect of group on right frontal pole activation: BO showed significantly greater activation than HC. There was a significant main effect of group on functional connectivity between the bilateral ventral striatum and the right ventrolateral prefrontal cortex (Z > 3.09, cluster-p < 0.05): BO showed significantly greater negative functional connectivity than other participants. These between-group differences remained after removing youth with psychiatric disorders and psychotropic medications from analyses. CONCLUSIONS: This is the first study to demonstrate that reward circuitry activation and functional connectivity distinguish BO from NBO and HC. The fact that the pattern of findings remained when comparing healthy BO v. healthy NBO v. HC suggests that these neuroimaging measures may represent trait-level neurobiological markers conferring either risk for, or protection against, BD in youth.
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Trastorno Bipolar , Hijo de Padres Discapacitados , Trastornos Mentales/fisiopatología , Red Nerviosa/fisiopatología , Corteza Prefrontal/fisiopatología , Recompensa , Adolescente , Niño , Femenino , Humanos , Imagen por Resonancia Magnética , MasculinoRESUMEN
OBJECTIVE: Bipolar disorder (BP) frequently co-occurs with other psychiatric disorders. We examine whether course of anxiety disorders (ANX), attention deficit hyperactivity disorder (ADHD), disruptive behavior disorders (DBD), and substance use disorders (SUD) influence likelihood of recovery and recurrence of depression and mania in BP youth. METHOD: Weekly ratings of psychiatric disorder intensity were obtained from 413 participants of the Course and Outcome of BP Youth project, followed for an average of 7.75 years. Multiple-event Cox proportional hazards regression analyses examined worsening of comorbid disorders as predictors of mood episode recovery and recurrence. RESULTS: Increased severity in ANX and SUD predicted longer time to recovery and less time to next depressive episode, and less time to next manic episode. Multivariate models with ANX and SUD found that significant effects of ANX remained, but SUD only predicted longer time to depression recovery. Increased severity of ADHD and DBD predicted shorter time to recurrence for depressive and manic episodes. CONCLUSION: There are significant time-varying relationships between the course of comorbid disorders and episodicity of depression and mania in BP youth. Worsening of comorbid conditions may present as a precursor to mood episode recurrence or warn of mood episode protraction.
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Trastornos de Ansiedad/psicología , Trastorno por Déficit de Atención con Hiperactividad/psicología , Déficit de la Atención y Trastornos de Conducta Disruptiva/psicología , Trastorno Bipolar/psicología , Trastornos Relacionados con Sustancias/psicología , Adolescente , Niño , Comorbilidad , Femenino , Humanos , Masculino , Problema de Conducta , Escalas de Valoración Psiquiátrica , Factores de RiesgoAsunto(s)
Inhibidores de la Angiogénesis/administración & dosificación , Neovascularización Patológica/tratamiento farmacológico , Receptores de Factores de Crecimiento Endotelial Vascular/administración & dosificación , Proteínas Recombinantes de Fusión/administración & dosificación , Degeneración Macular Húmeda/tratamiento farmacológico , Femenino , Humanos , MasculinoRESUMEN
PURPOSE: To evaluate frequency of injections, visual and anatomical outcomes of neovascular age-related macular degeneration (nAMD) patients transitioned to intravitreal aflibercept after failure to extend treatment interval beyond 8 weeks with prior intravitreal bevacizumab or ranibizumab. METHODS: Retrospective review of patients with nAMD switched to aflibercept following ≥ 6 prior intravitreal ranibizumab or bevacizumab injections at 4-8-week intervals. Three monthly aflibercept injections were given followed by a treat-and-extend dosing regimen. RESULTS: Twenty-one eyes of 18 patients who had received a mean of 23.8 ± 18.8 (mean ± SD; range 6-62) prior ranibizumab or bevacizumab injections were included. Over a mean follow-up of 24 months after the transition, 9.2 ± 2.9 (range 4-21) aflibercept injections were required. Interval between aflibercept injections increased to 57.3 days (range 35-133 days), as compared with 37 ± 6.1 days (range 29-54 days) with the prior agents (P = 0.01). Mean best-corrected visual acuity was preserved (0.42 ± 0.31 vs 0.42 ± 0.23 logMAR; P = 0.2). Mean OCT central subfoveal thickness (292.1 ± 83.2 µm to 283.6 ± 78.6 µm; P = 0.4) and mean macular volume (7.9 ± 0.95 mm(3) to 7.67 ± 0.94 mm(3); P = 0.16) remained stable. CONCLUSION: Patients requiring treatment more frequently than every 8 weeks with ranibizumab and bevacizumab were transitioned to > 8-week treatment interval with aflibercept while maintaining the anatomic and visual gains.
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Inhibidores de la Angiogénesis/administración & dosificación , Neovascularización Patológica/tratamiento farmacológico , Receptores de Factores de Crecimiento Endotelial Vascular/administración & dosificación , Proteínas Recombinantes de Fusión/administración & dosificación , Degeneración Macular Húmeda/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Bevacizumab/uso terapéutico , Sustitución de Medicamentos , Femenino , Humanos , Inyecciones Intravítreas , Masculino , Persona de Mediana Edad , Ranibizumab/uso terapéutico , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Agudeza VisualRESUMEN
OBJECTIVE: To determine the longitudinal impact of borderline personality disorder (BPD) on the course and outcome of bipolar disorder (BP) in a pediatric BP sample. METHOD: Participants (N = 271) and parents from the Course and Outcome of Bipolar Youth (COBY) study were administered structured clinical interviews and self-reports on average every 8.7 months over a mean of 93 months starting at age 13.0 ± 3.1 years. The structured interview for DSM-IV personality disorders (SIDP-IV) was administered at the first follow-up after age 18 to assess for symptoms of BPD. BPD operationalized at the disorder, factor, and symptom level, was examined as a predictor of poor clinical course of BP using all years of follow-up data. RESULTS: The number of BPD symptoms was significantly associated with poor clinical course of BP, above and beyond BP characteristics. Affective dysregulation was most strongly associated with poor course at the factor level; the individual symptoms most strongly associated with poor course were dissociation/stress-related paranoid ideation, impulsivity, and affective instability. CONCLUSION: BPD severity adds significantly to the burden of BP illness and is significantly associated with a more chronic and severe course and outcome beyond what can be attributable to BP characteristics.
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Trastorno Bipolar/psicología , Trastorno de Personalidad Limítrofe/psicología , Adolescente , Síntomas Afectivos/complicaciones , Síntomas Afectivos/psicología , Factores de Edad , Trastorno Bipolar/diagnóstico , Trastorno Bipolar/epidemiología , Trastorno de Personalidad Limítrofe/diagnóstico , Trastorno de Personalidad Limítrofe/epidemiología , Niño , Trastorno Depresivo Mayor/diagnóstico , Trastorno Depresivo Mayor/psicología , Femenino , Humanos , Conducta Impulsiva , Entrevista Psicológica/métodos , Estudios Longitudinales , Masculino , Escalas de Valoración Psiquiátrica , Estudios RetrospectivosRESUMEN
PURPOSE: To describe the efficacy of intravitreal aflibercept on 12-month visual and anatomical outcomes in patients with neovascular age-related macular degeneration (AMD) recalcitrant to prior monthly intravitreal bevacizumab or ranibizumab. METHODS: Non-comparative case series of 21 eyes of 21 AMD patients with evidence of persistent exudation (intraretinal fluid/cysts, or subretinal fluid (SRF), or both) on spectral domain OCT despite ≥6 prior intravitreal 0.5 mg ranibizumab or 1.25 mg bevacizumab (mean 29.8±17.1 injections) over 31.6±17.4 months who were transitioned to aflibercept. RESULTS: At baseline, best-corrected visual acuity (BCVA) was 0.42±0.28 logarithm of minimum-angle of resolution (logMAR), central foveal thickness (CFT) was 329.38±102.67 µm and macular volume (MV) was 7.71±1.32 mm(3). After 12 months of aflibercept (mean 10.2±1.2 injections), BCVA was 0.40±0.28 logMAR (P=0.5), CFT decreased to 292.71±91.35 µm (P=0.038) and MV improved to 7.33±1.27 mm(3) (P=0.003). In a subset of 15 eyes with a persistent fibrovascular or serous pigment epithelial detachment (PED), mean baseline PED greatest basal diameter (GBD) was 2350.9±1067.6 µm and mean maximal height (MH) was 288.7±175.9 µm. At 12 months, GBD improved to 1896.3±782.3 µm (P=0.028), while MH decreased to 248.27±146.2 µm (P=0.002). CONCLUSION: In patients with recalcitrant AMD, aflibercept led to anatomic improvement at 12 months, reduction in proportion of eyes with SRF and reduction in PED, while preserving visual acuity.
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Fóvea Central/patología , Receptores de Factores de Crecimiento Endotelial Vascular/uso terapéutico , Proteínas Recombinantes de Fusión/uso terapéutico , Agudeza Visual/fisiología , Degeneración Macular Húmeda/tratamiento farmacológico , Anciano de 80 o más Años , Femenino , Humanos , Inyecciones Intravítreas , Masculino , Líquido Subretiniano/efectos de los fármacos , Tomografía de Coherencia Óptica , Resultado del Tratamiento , Degeneración Macular Húmeda/fisiopatologíaRESUMEN
BACKGROUND: Neuroimaging measures of behavioral and emotional dysregulation can yield biomarkers denoting developmental trajectories of psychiatric pathology in youth. We aimed to identify functional abnormalities in emotion regulation (ER) neural circuitry associated with different behavioral and emotional dysregulation trajectories using latent class growth analysis (LCGA) and neuroimaging. METHOD: A total of 61 youth (9-17 years) from the Longitudinal Assessment of Manic Symptoms study, and 24 healthy control youth, completed an emotional face n-back ER task during scanning. LCGA was performed on 12 biannual reports completed over 5 years of the Parent General Behavior Inventory 10-Item Mania Scale (PGBI-10M), a parental report of the child's difficulty regulating positive mood and energy. RESULTS: There were two latent classes of PGBI-10M trajectories: high and decreasing (HighD; n=22) and low and decreasing (LowD; n=39) course of behavioral and emotional dysregulation over the 12 time points. Task performance was >89% in all youth, but more accurate in healthy controls and LowD versus HighD (p<0.001). During ER, LowD had greater activity than HighD and healthy controls in the dorsolateral prefrontal cortex, a key ER region, and greater functional connectivity than HighD between the amygdala and ventrolateral prefrontal cortex (p's<0.001, corrected). CONCLUSIONS: Patterns of function in lateral prefrontal cortical-amygdala circuitry in youth denote the severity of the developmental trajectory of behavioral and emotional dysregulation over time, and may be biological targets to guide differential treatment and novel treatment development for different levels of behavioral and emotional dysregulation in youth.
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Desarrollo del Adolescente/fisiología , Síntomas Afectivos/fisiopatología , Amígdala del Cerebelo/fisiopatología , Síntomas Conductuales/fisiopatología , Corteza Prefrontal/fisiopatología , Adolescente , Niño , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , MasculinoRESUMEN
Primary intraocular lymphoma is a distinct subset of primary non-Hodgkin's lymphoma of the central nervous system (CNS). Diagnosis can be difficult and is often delayed, as the clinical presentation can mimic a number of other ocular conditions. This report describes four different presentations of intraocular lymphoma and focuses on its modes of clinical presentation. Primary intraocular lymphoma can present with a wide variety of manifestations frequently mimicking diffuse uveitis that is refractory to corticosteroids. Subretinal pigment epithelium tumors may be seen. However, other presentations may include multiple deep white dots in the retina secondary to tumor infiltration; retinal infiltration, causing a necrotizing retinitis; or infiltration of the retinal vasculature, causing arterial or venous obstruction. Finally, optic nerve invasion may be seen. CNS lymphoma develops in the majority of patients before, in conjunction with, or after the development of eye disease. Intraocular lymphoma often has a fatal outcome, but recognition of its modes of presentation facilitates early diagnosis and treatment that may improve prognosis.
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Linfoma de Células B/diagnóstico , Linfoma de Células B Grandes Difuso/diagnóstico , Neoplasias del Nervio Óptico/diagnóstico , Neoplasias de la Retina/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Diagnóstico Diferencial , Humanos , Linfoma de Células B/mortalidad , Linfoma de Células B/terapia , Linfoma de Células B Grandes Difuso/mortalidad , Linfoma de Células B Grandes Difuso/terapia , Masculino , Persona de Mediana Edad , Neoplasias del Nervio Óptico/mortalidad , Neoplasias del Nervio Óptico/terapia , Pronóstico , Neoplasias de la Retina/mortalidad , Neoplasias de la Retina/terapia , Tasa de SupervivenciaRESUMEN
PURPOSE: To describe the characteristics, treatment, and outcome of five eyes with both choroidal neovascularization (CNV) and macular hole. METHODS: Medical records of five patients with both macular hole and CNV were reviewed. RESULTS: All eyes had full-thickness macular holes. Most eyes had atypical-appearing macular holes (subretinal hemorrhage, prominent subretinal fluid, or discoloration at the hole margin) at presentation or subsequently when CNV developed. Fluorescein angiography (FA) confirmed the presence of CNV in each eye. Three eyes underwent combined macular hole repair and CNV removal, and sustained closure of these macular holes was achieved. A fourth eye underwent successful argon laser photocoagulation of extrafoveal CNV, and macular hole surgery was declined. The final eye underwent two macular hole repairs before sustained closure was achieved. Final visual acuity, ranging from 20/100 to hand motions, was limited by macular pathology and/or cataract. CONCLUSIONS: Choroidal neovascularization can occur in association with a macular hole. In eyes with an atypical-appearing macular hole, FA should be obtained to detect CNV. Excision of the CNV can be done safely in conjunction with macular hole surgery. Final visual acuity may be limited by cumulative retinal and retinal pigment epithelium damage, especially in eyes with underlying macular disease.
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Neovascularización Coroidal/cirugía , Perforaciones de la Retina/cirugía , Adulto , Anciano , Neovascularización Coroidal/complicaciones , Neovascularización Coroidal/diagnóstico , Femenino , Angiografía con Fluoresceína , Fluorocarburos/uso terapéutico , Fondo de Ojo , Humanos , Coagulación con Láser , Persona de Mediana Edad , Perforaciones de la Retina/complicaciones , Perforaciones de la Retina/diagnóstico , Hexafluoruro de Azufre/uso terapéutico , Resultado del Tratamiento , Agudeza Visual , VitrectomíaRESUMEN
OBJECTIVE: To identify and examine the indications, outcomes and potential risks of strabismus surgery in visually mature patients. DESIGN: Case series. SETTING: University-based referral practice in Edmonton. PATIENTS: A total of 222 patients (115 females and 107 males) aged 9 to 69 (mean 29) years who underwent strabismus surgery for various types of strabismus (as grouped by original diagnosis). All patients were followed for at least 6 weeks postoperatively. OUTCOME MEASURES: Previous surgery and deviation in prism dioptres (delta) (distance and near), sensory status (measured by the Titmus stereotest at near) and the presence of symptoms (diplopia, abnormal head posture or asthenopia), recorded preoperatively, 6 weeks postoperatively and at the last postoperative visit. RESULTS: The patients were followed for an average of 14 months postoperatively. At the last postoperative visit 187 patients (84%) were aligned to within 15 delta of orthotropia. Overall, 116 patients (52%) demonstrated some degree of stereopsis postoperatively, compared with 78 (35%) preoperatively. A total of 116 patients (52%) had symptoms preoperatively, including diplopia, abnormal head posture or asthenopia; 88 (76%) of the 116 had complete resolution of their symptoms. Six patients (4%) without diplopia preoperatively were found to have this symptom postoperatively. CONCLUSIONS: The findings suggest that most visually mature patients under-going strabismus surgery can expect functional benefits, including improvement of alignment, preservation and occasionally restoration of sensory fusion, and elimination of diplopia, abnormal head posture and asthenopia.
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Estrabismo/fisiopatología , Estrabismo/cirugía , Visión Ocular/fisiología , Adolescente , Adulto , Anciano , Niño , Diplopía/complicaciones , Esotropía/cirugía , Exotropía/cirugía , Femenino , Estudios de Seguimiento , Cabeza/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias , Postura/fisiología , Estrabismo/complicaciones , Resultado del TratamientoRESUMEN
The effect of s.c. daily injections of 10 or 1000 ng 5 alpha-dihydrotestosterone (DHT)100 g body weight from birth to day 21, or from days 26 to 117 of age, on the changes in concentration of serum and pituitary gonadotrophins was investigated in male rats. Treatment with 10 ng DHT from days 1 to 21 depressed serum FSH, but not LH, at day 7, while 1000 ng DHT depressed both serum LH and FSH. Treatment with both doses of DHT reduced pituitary levels of LH and FSH at day 7, with FSH being more depressed than LH. Treatment with 10 ng DHT from days 26 to 117 increased serum FSH from days 82 to 117, while 1000 ng DHT did not have this effect. Treatment with 1000 ng, but not 10 ng, DHT between days 26 and 117 reduced pituitary levels of LH and FSH at day 40. Rats treated with the two doses of DHT from days 26 to 117 showed a difference in the responsiveness of the pituitary to LH-releasing hormone (LHRH). Treatment with 10 ng DHT enhanced LHRH-induced release of LH without affecting FSH release, while 1000 ng DHT depressed LHRH-induced release of FSH but not of LH. These findings support the view that DHT may play a modulatory role in the ontogeny of serum gonadotrophins and the responsiveness of the pituitary to LHRH during the onset of puberty in the male rat.
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Dihidrotestosterona/administración & dosificación , Hormona Folículo Estimulante/metabolismo , Hormona Luteinizante/metabolismo , Hipófisis/metabolismo , Animales , Dihidrotestosterona/farmacología , Hormona Folículo Estimulante/sangre , Hormona Liberadora de Gonadotropina/farmacología , Hormona Luteinizante/sangre , Masculino , Hipófisis/efectos de los fármacos , Ratas , Maduración SexualRESUMEN
Comparative in vitro studies on the release of LH and FSH by pituitary-hypothalamus complex (PHC) with intact portal plexus and whole pituitary (PI) from adult male rats showed that PHC released LH at a greater rate and in larger amounts than PI. PHC and PI released FSH in comparable amounts and rates. Attempts were made to correlate serum gonadotropin levels to that released by PHC and PI at 1, 3, 7, 14, 21 and 46 days of post-castration (PC). Sham operated animals served as controls. Castration increased serum LH and FSH levels but in different profiles. CPHC and CPI (PHC and PI from castrated rats) released less LH than NPHC and NPI (PHC and PI from sham operated controls) till day 14 PC after which CPHC and CPI released more LH than NPHC and NPI respectively. Castration abolished the intrinsic capacity of PHC to secrete more LH than PI. CPHC and CPI secreted significantly less FSH than NPHC and NPI at 1, 3 and 7 days PC. At days 14 and 21 of post-castration PCNCP or CPI and NPHC or NPI released similar amounts of FSH. Administration of 5 alpha-dihydrotestosterone (DHT, 1 mg/rat/day) or estradiol valerate (EV, 1 microgram/rat/day) immediately following castration prevented the rise in serum LH and FSH but increased the amounts of LH and FSH released by CPHC and CPI. The treatment caused a marked stimulation of FSH released by CPI.(ABSTRACT TRUNCATED AT 250 WORDS)
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Castración , Hormona Folículo Estimulante/metabolismo , Hormonas Esteroides Gonadales/farmacología , Sistema Hipotálamo-Hipofisario/metabolismo , Hormona Luteinizante/metabolismo , Animales , Dihidrotestosterona/farmacología , Estradiol/análogos & derivados , Estradiol/farmacología , Hormona Liberadora de Gonadotropina/metabolismo , Sistema Hipotálamo-Hipofisario/efectos de los fármacos , Técnicas In Vitro , Masculino , Hipófisis/metabolismo , RatasRESUMEN
Investigations were undertaken to study the effect of administering s.c. 10, 25, 50, 100, 500 and 1000 ng DHT/rat/day to normal adult male rats, for six weeks, on the basal levels of serum gonadotropin and the sensitivity of the pituitary to LHRH. The control group received olive oil. Animals were weighed and bled via cardiac puncture before the beginning of the treatment and weekly thereafter. After the last bleeding rats were injected intracardially 200 ng LHRH/rat and killed 15 min later. Blood, pituitary and testes were collected. Data were analyzed with respect to the control group and with respect to day zero of the treatment. DHT failed to produce a persistent effect on the serum gonadotropin. 10 and 500 ng DHT suppressed FSH levels significantly on days 21 and 7, respectively. 25, 50, 100 and 1000 ng DHT stimulated the release of FSH on day 42. 10 ng DHT reduced the levels of LH on day 14 of the treatment. 10, 25 and 50 ng DHT increased the sensitivity of the pituitary to release more LH in response to LHRH while 100, 500, 1000 ng DHT inhibited LHRH induced release of FSH. DHT at all doses tested failed to affect intrapituitary levels of LH and FSH. 10, 500 and 1000 ng DHT reduced the weights of the pituitaries as compared to the control group. The data demonstrate effects of DHT which are transient on the basal release of gonadotropins but are more persistent and differential on the sensitivity of the pituitary to LHRH.