Effects of chronic corticosterone and imipramine administration on panic and anxiety-related responses

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.

Induction of oxidative stress by restraint stress and corticosterone treatments in rats.

Chronic exposure to psychological stress in humans and restraint stress in experimental animals results in increased oxidative stress and resultant tissue damage. To study the contribution of stress hormones towards stress-induced oxidative processes in the brain, we investigated the response of important free-radical scavenging enzymes toward chronic administration of two doses of corticosterone (low dose: 10 mg/kg/day, high dose: 40 mg/kg/day) in rodents. After a 21-day experimental period, a significant decline in both superoxide dismutase and catalase was observed in both stressed and stress hormone-treated animals. The brain levels of glutathione as well as the activities of glutathione-S-transferase and glutathione reductase were also significantly decreased, while lipid peroxidation levels were significantly increased in comparison to controls. A direct pro-oxidant effect of stress hormones in the brain during physical and psychological stress was observed, indicating important implications for oxidative stress as a major pathological mechanism during chronic stress and a consequent target option for anti-stress therapeutic interventions.

Monocrotofós e estresse: efeitos da exposiçäo pré-natal no desenvolvimento físico e comportamental da prole de ratas / Monocrotophos and stress: effect of prenatal exposure in rats offsring's behavioral and physical development

O presente trabalho propôs-se a estudar os efeitos da exposiçäo pré-natal a dois fatores diversos: ao inseticida organofosforado monocrotofós e ao estresse por contençäo, durante o período organogênico, e evidenciar as possíveis alteraçöes no desenvolvimento físico e comportamental da prole de ratas observadas no período pós-natal. Foram utilizadas ratas Wistar prenhes subdivididas em dois grupos: estressado e näo estressado, que receberam, por gavage, do 6º ao 15º dias da gestaçäo, 1 mg/kg/dia do monocrotofós (tratado) ou água destilada (controle), e que após o parto tiveram suas ninhadas avaliadas quanto ao desenvolvimento físico e comportamental. Durante o período de tratamento as ratas dos grupos estressados (controle e tratado), apresentaram níveis plasmáticos de corticosterona, cerca de 3 vezes mais elevados do que o normal...

Effects of withdrawal of glucocorticoids on improving the function and enzymatic activities of liver mitochondria in female diabetic rats

En el presente trabajo se describen los efectos de la restitución de corticosterona a ratas con diabetes inducida por estreptozotocina sobre a) la función de mitocondrias enteras de hígado y b) sobre las actividades enzimáticas de la 3- hidroxibutirato deshidrogenasa (HBD), citocromo c oxidasa (Cox) y succinato deshidrogenasa (SD) de mitocondrias que sufrieron ruptura por método físico. La función mitocondrial fue analizadas por la respiración y por el comportamiento oscilatorio osmótico de esas organelas. La respiración se midió por método polarográfico y se midieron el estado 3 de la respiración activa (S3) y el control respiratorio (CR) usando los siguientes sustratos: 3-hidroxibutirato, malato-glutamato y succinato. El comportamiento oscilatorio osmótico se midió usando como parámetro comparativo los coeficientes de amortiguación (CA), que son los cocientes de las amplitudes de dos picos o valles consecutivos obtenidos en el registro espectrofotométrico de dicho fenómeno. Se dispusieron un grupo de ratas normales no diabéticas (N) y los siguientes grupos de ratas diabéticas: controles (D), adrenalectomizadas (D + ADX) y adrenalectomizadas con restitución de corticosterona (D + ADX + C). Los resultados de la respiración mitocondrial mostraron que los valores medios de S3 y CR disminuyeron con los tres sustratos en el grupo D + ADX + C comparado con el grupo D + ADX (p < 0,001). Este grupo demostró, a su vez, un aumento significativo de los valores medios de S3 y CR de respiración con respecto al del grupo D. El comportamiento oscilatorio de mitocondrias enteras de hígado del grupo D + ADX + C demostró un significativo aumento de los CA de picos y valles comparado con los del grupo D + ADX. Los valores de CA del último grupo no fueron significativamente diferentes de los del grupo N. El comportamiento de las actividades enzimáticas de mitocondrias fraccionadas fueron diferentes para cada enzima según los diferentes tratamientos en los grupos de ratas diabéticas. En el grupo D + ADX + C el valor medio de la actividad HBD disminuyó significativamente, el de la Cox aumentó (p < 0,02) y el de la SD no mostró variación alguna con respecto a los correspondientes valores medidos de esas enzimas en el grupo D + ADX. Asimismo, el valor medio de la actividad HBD en este último grupo fue similar al del grupo N y el de Cox fue menor (p < 0,001) que el del grupo D. Se concluye que la corticosterona tiene un significativo efecto diabetogénico sobre la función bioquími

Epidural steroid injection in non-specific low backache.

Effect of epidural steroid injection has been studied in 107 cases (50 males and 57 females, mostly above 20 years of age) with non-specific low backache. Out of 42 cases with acute syndrome 20(47.6%) showed good response, 10(23.8%) showed fair response and 12(28.6%) showed poor response, whereas similar responses were found in 5(7.7%), 10(15.4%) and 50(76.9%) cases respectively among 65 cases of chronic syndrome (p less than 0.001). Agewise, 23(32.9%), 9(12.9%) and 38(54.2%) cases among 70 patients below 40 years of age and 2(5.4%), 11(29.8%) and 24 (69.8%) cases among 37 patients above 40 years of age showed good, fair and poor responses to epidural steroid respectively (p less than 0.001). Hence epidural steroid injection has been shown to be a useful adjunct to conservative treatment of low backache in young patients with acute syndrome.