RESUMEN
Hot beverage consumption is a risk factor for esophageal squamous cell carcinoma, but the underlying mechanisms are still unknown. We developed an experimental mouse model to understand the mechanism of thermal lesion to esophageal carcinogenesis. Female BALB/c mice were treated by gavage with water at different temperatures three times a week and nitrosamines in the drinking water. Water at 70°C, but not at lower temperatures, initially induced an esophageal necrosis that healed and became resistant to necrosis after further administrations. However, when 70°C water was associated with N-nitrosodiethylamine at doses above 1 ppm, there was interference in epithelial regeneration, allowing recurrent thermal injury and inflammation. Recurrent thermal injury resulted in hyper proliferative premalignant lesions being induced earlier (at 4 weeks) and at a higher frequency (4-fold increase at 16 weeks) when compared to mice treated with NDEA only. Ki-67 immunostaining revealed that recurrent thermal injury induced basal cell proliferation resulting in the expansion of epithelial basal cells, confirmed by the increase in cytokeratin 14 positive cells with concomitant reduction of differentiated cytokeratin 5 positive cells. We conclude that recurrent thermal lesion may act as a tumor promoter though a strong proliferation stimulus of esophageal epithelial basal cells.
Asunto(s)
Proliferación Celular/efectos de los fármacos , Agua Potable/administración & dosificación , Esófago/patología , Calor , Lesiones Precancerosas/patología , Animales , Dietilnitrosamina/administración & dosificación , Dietilnitrosamina/toxicidad , Agua Potable/efectos adversos , Agua Potable/química , Esófago/metabolismo , Femenino , Inmunohistoquímica , Antígeno Ki-67/metabolismo , Ratones Endogámicos BALB C , Lesiones Precancerosas/etiología , Lesiones Precancerosas/metabolismo , Mucosa Respiratoria/efectos de los fármacos , Mucosa Respiratoria/metabolismo , Mucosa Respiratoria/patología , Análisis de Supervivencia , Factores de TiempoRESUMEN
It is known that chronic high levels of corticosterone (CORT) enhance aversive responses such as avoidance and contextual freezing. In contrast, chronic CORT does not alter defensive behavior induced by the exposure to a predator odor. Since different defense-related responses have been associated with specific anxiety disorders found in clinical settings, the observation that chronic CORT alters some defensive behaviors but not others might be relevant to the understanding of the neurobiology of anxiety. In the present study, we investigated the effects of chronic CORT administration (through surgical implantation of a 21-day release 200 mg pellet) on avoidance acquisition and escape expression by male Wistar rats (200 g in weight at the beginning of the experiments, N = 6-10/group) tested in the elevated T-maze (ETM). These defensive behaviors have been associated with generalized anxiety and panic disorder, respectively. Since the tricyclic antidepressant imipramine is successfully used to treat both conditions, the effects of combined treatment with chronic imipramine (15 mg, ip) and CORT were also investigated. Results showed that chronic CORT facilitated avoidance performance, an anxiogenic-like effect (P < 0.05), without changing escape responses. Imipramine significantly reversed the anxiogenic effect of CORT (P < 0.05), although the drug did not exhibit anxiolytic effects by itself. Confirming previous observations, imipramine inhibited escape responses, a panicolytic-like effect. Unlike chronic CORT, imipramine also decreased locomotor activity in an open field. These data suggest that chronic CORT specifically altered ETM avoidance, a fact that should be relevant to a better understanding of the physiopathology of generalized anxiety and panic disorder.
Asunto(s)
Animales , Masculino , Ratas , Antidepresivos Tricíclicos/administración & dosificación , Ansiedad/tratamiento farmacológico , Conducta Animal/efectos de los fármacos , Corticosterona/administración & dosificación , Imipramina/administración & dosificación , Trastorno de Pánico/tratamiento farmacológico , Antidepresivos Tricíclicos/farmacología , Corticosterona/farmacología , Reacción de Fuga/efectos de los fármacos , Imipramina/farmacología , Aprendizaje por Laberinto/efectos de los fármacos , Actividad Motora/efectos de los fármacos , Ratas WistarRESUMEN
It is known that chronic high levels of corticosterone (CORT) enhance aversive responses such as avoidance and contextual freezing. In contrast, chronic CORT does not alter defensive behavior induced by the exposure to a predator odor. Since different defense-related responses have been associated with specific anxiety disorders found in clinical settings, the observation that chronic CORT alters some defensive behaviors but not others might be relevant to the understanding of the neurobiology of anxiety. In the present study, we investigated the effects of chronic CORT administration (through surgical implantation of a 21-day release 200 mg pellet) on avoidance acquisition and escape expression by male Wistar rats (200 g in weight at the beginning of the experiments, N = 6-10/group) tested in the elevated T-maze (ETM). These defensive behaviors have been associated with generalized anxiety and panic disorder, respectively. Since the tricyclic antidepressant imipramine is successfully used to treat both conditions, the effects of combined treatment with chronic imipramine (15 mg, ip) and CORT were also investigated. Results showed that chronic CORT facilitated avoidance performance, an anxiogenic-like effect (P < 0.05), without changing escape responses. Imipramine significantly reversed the anxiogenic effect of CORT (P < 0.05), although the drug did not exhibit anxiolytic effects by itself. Confirming previous observations, imipramine inhibited escape responses, a panicolytic-like effect. Unlike chronic CORT, imipramine also decreased locomotor activity in an open field. These data suggest that chronic CORT specifically altered ETM avoidance, a fact that should be relevant to a better understanding of the physiopathology of generalized anxiety and panic disorder.
Asunto(s)
Antidepresivos Tricíclicos/administración & dosificación , Ansiedad/tratamiento farmacológico , Conducta Animal/efectos de los fármacos , Corticosterona/administración & dosificación , Imipramina/administración & dosificación , Trastorno de Pánico/tratamiento farmacológico , Animales , Antidepresivos Tricíclicos/farmacología , Corticosterona/farmacología , Reacción de Fuga/efectos de los fármacos , Imipramina/farmacología , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Actividad Motora/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
OBJECTIVE: A prospective, double-blind, randomized, controlled trial was conducted to evaluate the growth and nutritional status of preterm infants receiving preterm human milk supplemented with a newly formulated powdered human milk fortifier (HMF), study fortifier (SF), or a powdered commercial HMF (CF). METHODS: Infants (n = 144) with a birth weight =1600 g and gestational age at birth of =33 weeks were enrolled and randomized before 21 days of life. Study day (SDAY) 1 was defined as the day full-strength fortification (4 packets/100 mL) began and the infant reached an intake of at least 100 mL/kg/day. Growth, biochemical indices of nutritional status, enteral intake, feeding tolerance, clinical histories, and morbidity were assessed serially. The primary outcome variable was weight gain (g/kg/day) from SDAYs 1 to 29 or hospital discharge, whichever came first. RESULTS: Infants fed human milk supplemented with SF consistently grew more rapidly from SDAYs 1 to 29 (or hospital discharge), regardless of whether the statistical analyses were performed on all subjects who were randomized into the study and reached SDAY 1 (intent-to-treat) or were limited to those able to adhere strictly to the feeding protocol of the study (subgroup). Using mean values adjusted for study site (least square [LS] means), the weight gain differences were 2.6 and 3.8 g/kg/day for the intent-to-treat and subgroup analyses, respectively. Likewise, the length-gain differences were.14 and.18 cm/week for the intent-to-treat and subgroup analyses, respectively. Infants in the SF group reached a weight of 1800 g at SDAY 18, and those in the CF group at SDAY 25. Mean alkaline phosphatase values among infants in the SF group were higher than for the CF infants (eg, LS means: 327 U/L vs 272 U/L, intent-to-treat analysis), likely reflecting the more rapid linear growth of the SF infants. Mean serum calcium values tended to be lower in the SF group in the intent-to-treat analysis and were significantly lower in the subgroup analysis (LS means: 10.3 mg/dL vs 11.2 mg/dL). Both fortifiers were generally well-tolerated, although an increased number of infants in the CF group exited the feeding protocol because of gastric residuals and abdominal distention. CONCLUSION: A new powdered HMF was shown to enhance the growth of preterm infants, compared with a commercially available powdered HMF in the United States.