Tocotrienol‐rich fraction supplementation prevents foetal loss in females mated with corticosterone‐treated male Sprague–Dawley rats

This study examined whether tocotrienol supplementation to corticosterone‐treated male rats could prevent foetal loss in females upon their mating. Epididymides of adult male Sprague–Dawley (SD) rats with proven fertility were surgically separated at the testis‐caput junction. Twenty‐four hours post‐surgery, these animals received for 7 days either: tocopherol‐stripped corn oil (Control), corticosterone 25 mg/kg s.c. (CORT), CORT 25 mg/kg s.c. and tocotrienol‐rich fraction (TRF) 100 mg/kg orally (CORT + TRF) or TRF 100 mg/kg orally (TRF). On day 8, males were cohabited with proestrus females. A spermatozoa‐positive vaginal smear indicated pregnancy. Males were euthanised for analysis of testosterone and antioxidant activities. Reproductive organs were weighed. On day 8 of pregnancy, females were laparotomised to count the number of implantation sites. Pregnancy was continued until term. Number of pups delivered and their weights were determined. Data were analysed using ANOVA. Malondialdehyde levels were significantly lower in CORT + TRF group compared with CORT group. Enzymatic antioxidant activities, testosterone level and reproductive organ weights were significantly higher in CORT + TRF group compared with CORT group. Number of implantation sites and live pups delivered, and their birth weights from females mated with CORT + TRF males were significantly higher compared to CORT group. Therefore, TRF prevents foetal loss in females mated with CORT + TRF‐treated males.     

Altered Circadian Rhythms of the Stress Hormone and Melatonin Response in Lupus-prone MRL/MP-fas Mice

The immune system interacts with the hypothalamo-pituitary-adrenal axis via so-called glucocorticoid increasing factors, which are produced by the immune system during immune reactions, causing an elevation of systemic glucocorticoid levels that contribute to preservation of the immune reactions specificities. Previous results from our laboratory had already shown an altered immuno-neuroendocrine dialogue via the hypothalamo-pituitary-adrenal axis in autoimmune disease-prone chicken and mouse strains. In the present study, we further investigated the altered glucocorticoid response via the hypothalamo-pituitary-adrenal axis in murine lupus. We established the circadian rhythms of corticosterone, dehydroepiandrosterone-sulfate, adrenocorticotropic hormone and melatonin, as well as the time response curves after injection of interleukin-1 of the first three parameters in normal SWISS and lupus-prone MRL/MP- fas^Iprmice. The results show that lupus-prone MRL/MP- fas^Iprmice do not react appropriately to changes of the light/dark cycle, circadian melatonin rhythms seem to uncouple from the light/dark cycle, and plasma corticosterone levels are elevated during the resting phase. Diurnal changes of dehydroepiandrosterone-sulfate and adrenocorticotropic hormone were normal compared to healthy controls. These data indicate that MRL/ MP- fas^Iprmice not only show an altered glucocorticoid response mediated via the hypothalamo pituitary adrenal axis to IL-1, but are also affected by disturbances of corticosterone and melatonin circadian rhythms. Our findings may have implications for intrathymic T cell development and the emergence of autoimmune disease.     

Regulation of Liver and Kidney Glucose-6-phosphatase Gene Expression in Hemorrhage and Resuscitation

The authors have recently demonstrated that increased gene expression of glucose-6-phosphatase (Glu-6-Pase) in hemorrhagic hypotension (HH) and following lactated Ringer's resuscitation (LR) is associated with a decrease in insulin and an increase in corticosterone concentrations. OBJECTIVE: To evaluate the in-vivo role of hormones the authors used insulin (IN), phentolamine and propranolol (PP) as an adrenergic blocker, and cyclic somatostatin (CS) as a glucagon blocker to prevent the induction of Glu-6-Pase gene expression in liver and kidney following HH and LR. METHODS: Hemorrhage was induced in fasted anesthetized rats, and the reduction of blood pressure to 40 mm Hg for a duration of 30 minutes was accomplished by withdrawal or infusion of shed blood. The resuscitated group underwent hemorrhage followed by fluid resuscitation with lactated Ringer's solution. RESULTS: Neither PP nor CS treatment could block the induction of Glu-6-Pase messenger ribonucleic acid (mRNA) following either HH or LR. However, the administration of IN significantly prevented the increase of Glu-6-Pase mRNA level and activity in both liver and kidney following HH and LR. This was associated with a normalization of plasma glucose, corticosterone, and glucagon levels and glucose-6-phosphate concentrations in liver and kidney toward prehemorrhage levels. CONCLUSIONS: These results indicate that in-vivo treatment with insulin during hemorrhagic hypotension and resuscitation is capable of preventing the increase in Glu-6-Pase gene expression in liver and kidney responsible for the observed hyperglycemia.     

丁螺环酮对皮质酮所致PC12细胞损伤的保护作用

提取大鼠大脑皮层突触膜并与丁螺环酮6.2 5～ 4 0 0 0 μmol·L- 1直接孵育 ,放射免疫法测定cAMP含量 ,发现丁螺环酮可浓度依赖地提高cAMP产生量 ,说明腺苷酸环化酶 (AC)活性升高 .神经生长因子 2 ,10kU·L- 1,三环类抗抑郁剂地昔帕明2 .5 ,5 μmol·L- 1或丁螺环酮 5 ,10 ,2 0 μmol·L- 1分别与皮质酮 0 .2mmol·L- 1共孵PC12细胞 4 8h ,均可防止皮质酮所致的PC12神经细胞损伤 ,使存活细胞增多 .结果提示丁螺环酮激活信号转导系统AC cAMP通路 ,从而对损伤神经元产生保护作用 ,这可能与其抗抑郁 ,抗焦虑作用有关 .     

整合素信号通路可能参与大鼠束缚应激后的恢复过程

目的筛选与束缚应激大鼠应激反应恢复速度相关的基因,探讨应激反应个体恢复的分子机制。方法观察大鼠2小时束缚应激后血浆促肾上腺皮质激素（adrenocorticotropic-hormone,ACTH）及皮质酮的变化规律,根据应激结束后1小时的血浆ACTH及皮质酮下降程度将大鼠分为快速恢复组与慢速恢复组。采用微阵列技术检测快速恢复组与慢速恢复组下丘脑组织基因表达的差异,用实时逆转录-聚合酶链反应验证部分基因的表达差异。结果基因芯片分析结果显示：大部分基因在两组间并无差异表达,在11个差异表达的基因中,快速恢复组中参与整合素信号通路的踝蛋白（talin）、整合素α6和丝/苏氨酸蛋白磷酸酶PP1β催化亚基（serine/threonine pro-tein phosphatase PP1-beta catalytic subunit,PP1B）基因有1.5倍上调,而结合粘附分子1（junctional adhesion mol-ecule 1, F11r）基因有 1.5 倍下调。实时逆转录 - 聚合酶链反应结果与芯片分析结果一致。结论本研究构建了束缚应激大鼠恢复过程的下丘脑基因表达谱,结果提示整合素信号通路可能参与应激的恢复过程。     

Early life trauma decreases glucocorticoid receptors in rat dentate gyrus upon adult re-stress: reversal by escitalopram

Early exposure to adverse experiences may lead to specific changes in hippocampal glucocorticoid function resulting in abnormalities within the hypothalamic-adrenal axis. Given interactions between the neuroendocrine and central serotonergic systems, we hypothesized that exposure to early trauma would lead to abnormal hypothalamic-adrenal axis activity that would be normalized by pretreatment with a selective serotonin re-uptake inhibitor. Hypothalamic-adrenal axis function was assessed by determining basal corticosterone levels and hippocampal glucocorticoid receptor immunoreactivity. Rats were subjected to a triple stressor on postnatal day 28, and again to a single swim re-stress session on postnatal day 35 and postnatal day 60. On postnatal day 61 i.e. 24 h after the last re-stress, trunk blood was collected for serum corticosterone determinations and hippocampal tissue was collected for immunohistochemistry of glucocorticoid receptors. Escitalopram (5mg/kg) or saline vehicle was administered from postnatal day 47-postnatal day 60 via osmotic mini-pumps. Animals exposed to early life trauma showed an increase in basal corticosterone levels, and a significant decrease in the ratio of glucocorticoid receptor positive cells to total cells in the hilus, granule cell layer and the dentate gyrus. Both the increase in basal corticosterone and decrease in glucocorticoid receptor immunoreactivity were reversed by escitalopram pretreatment. These data confirm alterations in hypothalamic-adrenalaxis function that may stem from decreases in glucocorticoid receptor levels, in response to early adverse experiences, and demonstrate that these alterations are reversed by serotonin re-uptake inhibitor pretreatment.     

11beta-Hydroxysteroid dehydrogenase type 2 protects the neonatal cerebellum from deleterious effects of glucocorticoids

11beta-Hydroxysteroid dehydrogenase type 2 is a glucocorticoid metabolizing enzyme that catalyzes rapid inactivation of corticosterone and cortisol to inert 11-keto derivatives. As 11beta-hydroxysteroid dehydrogenase type 2 is highly expressed in the developing brain, but not in the adult CNS, we hypothesized that it may represent a protective barrier to the deleterious actions of corticosteroids on proliferating cells. To test this hypothesis we have investigated the development and growth of the cerebellum in neonatal C57BL/6 mice and mice lacking 11beta-hydroxysteroid dehydrogenase type 2 (-/-). 11beta-Hydroxysteroid dehydrogenase type 2-/- mice had consistently lower body weight throughout the neonatal period, coupled with a smaller brain size although this was normalized when corrected for body weight. The cerebellar size was smaller in 11beta-hydroxysteroid dehydrogenase type 2-/- mice, due to decreases in size of both the molecular and internal granule layers. When exogenous corticosterone was administered to the pups between postnatal days 4 and 13, 11beta-hydroxysteroid dehydrogenase type 2(-/-) mice were more sensitive, showing further inhibition of cerebellar growth while the wildtype mice were not affected. Upon withdrawal of exogenous steroid, there was a rebound growth spurt so that at day 21 postnatally, the cerebellar size in 11beta-hydroxysteroid dehydrogenase type 2-/- mice was similar to untreated mice of the same genotype. Furthermore, 11beta-hydroxysteroid dehydrogenase type 2-/- mice had a delay in the attainment of neurodevelopmental landmarks such as negative geotaxis and eye opening. We therefore suggest that 11beta-hydroxysteroid dehydrogenase type 2 acts as to protect the developing nervous system from the deleterious consequences of glucocorticoid overexposure.     

Glucocorticoids interact with emotion-induced noradrenergic activation in influencing different memory functions

Extensive evidence from rat and human studies indicates that glucocorticoid hormones influence cognitive performance. Posttraining activation of glucocorticoid-sensitive pathways dose-dependently enhances the consolidation of long-term memory. Glucocorticoid effects on memory consolidation rely on noradrenergic activation of the basolateral amygdala and interactions of the basolateral amygdala with other brain regions. Glucocorticoids interact with the noradrenergic system both at a postsynaptic level, increasing the efficacy of the beta-adrenoceptor-cyclic AMP/protein kinase A system, as well as presynaptically in brainstem noradrenergic cell groups that project to the basolateral amygdala. In contrast, memory retrieval and working memory performance are impaired with high circulating levels of glucocorticoids. Glucocorticoid-induced impairment of these two memory functions also requires the integrity of the basolateral amygdala and the noradrenergic system. Such critical interactions between glucocorticoids and noradrenergic activation of the basolateral amygdala have important consequences for the role of emotional arousal in enabling glucocorticoid effects on these different memory functions.     

Behavioral, central monoaminergic and hypothalamo-pituitary-adrenal axis correlates of fear-conditioned analgesia in rats

Fear-conditioned analgesia is an important survival response which is expressed upon re-exposure to a context previously paired with a noxious stimulus. The aim of the present study was to characterize further the behavioral, monoaminergic and hypothalamo-pituitary-adrenal axis alterations associated with expression of fear-conditioned analgesia. Rats which had received footshock conditioning 24 h earlier, exhibited reduced formalin-evoked nociceptive behavior upon re-exposure to the footshock chamber, compared with non-footshocked formalin-treated rats. Intra-plantar injection of formalin reduced the duration of contextually-induced freezing and 20-40 kHz ultrasound emission. Intra-plantar injection of formalin to non-footshocked, non-conditioned rats did not induce ultrasonic vocalizations. Intra-plantar injection of formalin to footshock-conditioned rats, significantly increased tissue levels of 3,4-dihydroxyphenylacetic acid and the 3,4-dihydroxyphenylacetic acid:dopamine ratio in the periaqueductal gray and reduced levels of dopamine in the thalamus, compared with saline-treated footshocked controls. Non-footshocked, non-conditioned rats were capable of mounting a robust formalin-evoked increase in plasma corticosterone levels. Moreover, plasma corticosterone levels were significantly higher in saline-treated, footshock conditioned rats compared with saline-treated non-footshocked rats and levels did not differ between saline- and formalin-treated footshock conditioned rats. Assessment of the effects of the intra-plantar injection procedure revealed an attenuation of short-term extinction of contextually-induced freezing in rats anesthetized for intra-plantar injection of saline compared with non-anesthetized, non-injected rats as well as discrete effects on monoamines, their metabolites and plasma corticosterone levels. These data extend behavioral characterization of the phenomenon of fear-conditioned analgesia and suggest that measurement of ultrasound emission may be used as an ethologically relevant index of the defense response during fear-conditioned analgesia. Ultrasonic vocalization may also be a useful behavioral output to aid separation of nociception and aversion. The data provide evidence for discrete alterations in dopaminergic activity in the periaqueductal gray and thalamus and for altered hypothalamo-pituitary-adrenal axis activity following expression of defensive behavior.