On arrival in the Arctic, migrant birds must adjust their physiology and behavior to unpredictable snow cover, weather, food sources and predator pressure. In other words they must be resistant to environmental pertur...On arrival in the Arctic, migrant birds must adjust their physiology and behavior to unpredictable snow cover, weather, food sources and predator pressure. In other words they must be resistant to environmental perturbations (stress) so that they can migrate to their tundra nesting areas and settle on territories as soon as possible. They can then begin breeding as soon as when environmental conditions become favorable. They do this partly by using micro-habitats such as areas where snow depth is low, and patches of tundra that melt out rapidly (especially near willows Salix sp). Ground temperatures increase dramatically within hours after exposure to sun; and invertebrate activity begins simultaneously. Wind speeds are attenuated almost completely within 10 cm of the ground in willows and tussock tundra. The combination of these conditions provides an ideal refuge, especially for passerine migrants in early spring. However, if conditions worsen, the birds can leave. There are adjustments of the adrenocortical responses to stress because arctic conditions in spring are potentially severe, at least compared with wintering grounds to the south. Secretion of corticosterone in response to acute stress is enhanced at arrival in males, accompanied by a decrease in sensitivity to negative feedback and a change in responsiveness of the adrenal cortex cells to adrenocorticotropin. There is also an increase in levels of corticosterone-binding globulin (CBG) so that the actions of corticosterone are buffered according to the severity of environmental conditions. Regulation at the level of genomic receptors, particularly the low affinity glucocorticosteroid-like receptor for corticosterone in brain and liver, may be important; and non-genomic actions of corticosterone may play a major role too. In other words, the hormone-behavior system associated with arrival biology is highly flexible.展开更多
Objective： To explore the effect of high dose of glucocorticoid （GC） on the synthesis of corticotropin releasing hormone （CRH） and transcription of its mRNA in hypothalamus paraventricular nuclei （PVN） in order...Objective： To explore the effect of high dose of glucocorticoid （GC） on the synthesis of corticotropin releasing hormone （CRH） and transcription of its mRNA in hypothalamus paraventricular nuclei （PVN） in order to investigate its difference with that of traditional GC effects and to add a new possible explanation to the mechanism of clinical applications of high dose of GC. Methods： A total of 60 rats were divided into 5 groups： blank control, 10^-6 mol/L dexamethasone （DEX） group, 10^-9 mol/L DEX group, 0.9% saline group and GR blocking group （10^-2mol/L RU486）. All agents were administrated through the femoral vein. CRH protein expression was measured by immunohistochemistry and laser confocal scanning microscopy （LCSM）; CRH mRNA level was explored by in situ hybridization. Results： 10^-6 mol/L DEX made CRH mRNA transcripted after 20 min and its protein expressed in PVN after 30 min, while normal level of DEX and 0.9% saline could not. If GR was blocked in advance, the effect of high dose of DEX disappeared. Conclusion ： High dose of GC can have CRH increased in PVN, which differs to the effect of traditional GC. And mGRH may play an important role in the effect of high dose of GC but not classic iGR.展开更多
THE causes of Cushing＇s syndrome are mainly di- vided into adrenocorticotropic hormone （ACTH） dependent and independent. ACTH dependent hypercortisolism represents excess ACTH se-creting by the pituitary or tumor o...THE causes of Cushing＇s syndrome are mainly di- vided into adrenocorticotropic hormone （ACTH） dependent and independent. ACTH dependent hypercortisolism represents excess ACTH se-creting by the pituitary or tumor outside the pituitary; and the latter one is also called as ectopic ACTH syndrome. Thorax is the most common location of causative lesions for ectopic ACTH syndrome, and the size of lesion is too small to be detected in some cases.1＇ 2 Cryptococcal pneumonia usually occurs in immunocompromised patients and excess cortisol production can theoretically produce a state of immunodeficiency. Development of cryptococcal pneumonia concomitant with Cushing syndrome （CS） was rare. Here, we report a case of pulmonary nodule in a patient with CS differentiated with ectopic ACTH-producing tumor. Crypto- coccal pneumonia was diagnosed followinglung resection.展开更多
A study has been carried out with fourteen healthy mature cats in order to determine the effect of a xylazine-ketamine anesthetic protocol （group X/K） on blood concentrations of adrenaline, ACTH （adrenocorticotropi...A study has been carried out with fourteen healthy mature cats in order to determine the effect of a xylazine-ketamine anesthetic protocol （group X/K） on blood concentrations of adrenaline, ACTH （adrenocorticotropic hormone）, cortisol, insulin and glucose in comparison with a control group （group K--no anesthesia and surgery）. The animals were randomly allocated in two groups （n = 7）. The premeditation in the experimental group was made with xylazine 2 mg/kg intramuscularly. Induction and maintenance of anesthesia were made with ketamine 10 mg/kg intramuscularly. Ovariohysterectomy was performed upon occurrence of deep anesthesia. Blood specimens were obtained at 0, 30, 60, 120 min and 24 h from the two groups. Pronounced decrease in blood ACTH, cortisol, and adrenaline in group X/K was determined by the 30 min. Significant hyperglycemia together with hyperinsulinemia in the X/K group was established at the 120 min from the beginning of the anesthesia. Anesthesia with xylazine and ketamine led to reduction of the blood levels of stress hormones immediately after the beginning of anesthesia and caused a remarkable hyperglycemia with hyperinsulinemia.展开更多
文摘On arrival in the Arctic, migrant birds must adjust their physiology and behavior to unpredictable snow cover, weather, food sources and predator pressure. In other words they must be resistant to environmental perturbations (stress) so that they can migrate to their tundra nesting areas and settle on territories as soon as possible. They can then begin breeding as soon as when environmental conditions become favorable. They do this partly by using micro-habitats such as areas where snow depth is low, and patches of tundra that melt out rapidly (especially near willows Salix sp). Ground temperatures increase dramatically within hours after exposure to sun; and invertebrate activity begins simultaneously. Wind speeds are attenuated almost completely within 10 cm of the ground in willows and tussock tundra. The combination of these conditions provides an ideal refuge, especially for passerine migrants in early spring. However, if conditions worsen, the birds can leave. There are adjustments of the adrenocortical responses to stress because arctic conditions in spring are potentially severe, at least compared with wintering grounds to the south. Secretion of corticosterone in response to acute stress is enhanced at arrival in males, accompanied by a decrease in sensitivity to negative feedback and a change in responsiveness of the adrenal cortex cells to adrenocorticotropin. There is also an increase in levels of corticosterone-binding globulin (CBG) so that the actions of corticosterone are buffered according to the severity of environmental conditions. Regulation at the level of genomic receptors, particularly the low affinity glucocorticosteroid-like receptor for corticosterone in brain and liver, may be important; and non-genomic actions of corticosterone may play a major role too. In other words, the hormone-behavior system associated with arrival biology is highly flexible.
文摘Objective： To explore the effect of high dose of glucocorticoid （GC） on the synthesis of corticotropin releasing hormone （CRH） and transcription of its mRNA in hypothalamus paraventricular nuclei （PVN） in order to investigate its difference with that of traditional GC effects and to add a new possible explanation to the mechanism of clinical applications of high dose of GC. Methods： A total of 60 rats were divided into 5 groups： blank control, 10^-6 mol/L dexamethasone （DEX） group, 10^-9 mol/L DEX group, 0.9% saline group and GR blocking group （10^-2mol/L RU486）. All agents were administrated through the femoral vein. CRH protein expression was measured by immunohistochemistry and laser confocal scanning microscopy （LCSM）; CRH mRNA level was explored by in situ hybridization. Results： 10^-6 mol/L DEX made CRH mRNA transcripted after 20 min and its protein expressed in PVN after 30 min, while normal level of DEX and 0.9% saline could not. If GR was blocked in advance, the effect of high dose of DEX disappeared. Conclusion ： High dose of GC can have CRH increased in PVN, which differs to the effect of traditional GC. And mGRH may play an important role in the effect of high dose of GC but not classic iGR.
文摘THE causes of Cushing＇s syndrome are mainly di- vided into adrenocorticotropic hormone （ACTH） dependent and independent. ACTH dependent hypercortisolism represents excess ACTH se-creting by the pituitary or tumor outside the pituitary; and the latter one is also called as ectopic ACTH syndrome. Thorax is the most common location of causative lesions for ectopic ACTH syndrome, and the size of lesion is too small to be detected in some cases.1＇ 2 Cryptococcal pneumonia usually occurs in immunocompromised patients and excess cortisol production can theoretically produce a state of immunodeficiency. Development of cryptococcal pneumonia concomitant with Cushing syndrome （CS） was rare. Here, we report a case of pulmonary nodule in a patient with CS differentiated with ectopic ACTH-producing tumor. Crypto- coccal pneumonia was diagnosed followinglung resection.
文摘A study has been carried out with fourteen healthy mature cats in order to determine the effect of a xylazine-ketamine anesthetic protocol （group X/K） on blood concentrations of adrenaline, ACTH （adrenocorticotropic hormone）, cortisol, insulin and glucose in comparison with a control group （group K--no anesthesia and surgery）. The animals were randomly allocated in two groups （n = 7）. The premeditation in the experimental group was made with xylazine 2 mg/kg intramuscularly. Induction and maintenance of anesthesia were made with ketamine 10 mg/kg intramuscularly. Ovariohysterectomy was performed upon occurrence of deep anesthesia. Blood specimens were obtained at 0, 30, 60, 120 min and 24 h from the two groups. Pronounced decrease in blood ACTH, cortisol, and adrenaline in group X/K was determined by the 30 min. Significant hyperglycemia together with hyperinsulinemia in the X/K group was established at the 120 min from the beginning of the anesthesia. Anesthesia with xylazine and ketamine led to reduction of the blood levels of stress hormones immediately after the beginning of anesthesia and caused a remarkable hyperglycemia with hyperinsulinemia.
