Acidic fibroblast growth factor activates hypothalamic-pituitary-adrenocortical axis in rats.

Effects of acidic fibroblast growth factor (aFGF), an endogenous satiety substance, on the hypothalamic-pituitary-adrenocortical axis were examined under pentobarbital sodium anesthesia in rats. A guide cannula was inserted into the cerebral third ventricle and a vascular indwelling catheter was inserted into the right atrium from the jugular vein 2 wk and 3 days, respectively, before the experiment. A marked dose-dependent increase in plasma corticosterone was detected from 20 min to 2 h after intracerebroventricular administration of aFGF (1-10 ng). Significant increases in plasma adrenocorticotropic hormone (ACTH) were observed from 5 to 150 min after the intracerebroventricular administration of 10 ng aFGF. Significant dose-dependent increases in plasma corticosterone were also observed after intravenous injections of aFGF (1, 10, and 100 ng), together with increases in the plasma ACTH level. Pretreatment with antibody to corticotropin-releasing factor via the intracerebroventricular route abolished the increases in corticosterone induced by intracerebroventricularly administered aFGF, but not those induced by intravenous injection of aFGF. In adrenal glands perfused in situ with artificial medium, the corticosterone secretion rate increased slightly in response to 10(-9) M aFGF. These findings suggest that intracerebroventricular administration of aFGF activates the hypothalamic-pituitary-adrenal axis via corticotropin-releasing factor release in the brain, whereas peripheral administration of aFGF activates adrenocortical secretion mainly via a direct action on ACTH release.

Inhibitory actions of prostaglandin E1 on neurogenic plasma extravasation in rat airways.

To determine whether neurogenic inflammation can be inhibited by prostaglandin E1 (PGE1), that is suggested to have an inhibitory effect on neuropeptide release from airway sensory nerves, we examined plasma extravasation in the airways of anesthetized rats in vivo with Evans blue due as a marker. Neurogenic inflammation was produced by an i.v. injection of capsaicin (100 micrograms/kg) or by antidromic electrical stimulation of the right vagus nerve (4 Hz, 1 ms, 4 V for 1 min). Capsaicin injection significantly increased leakage of dye in the trachea and main bronchi. Similar increases in leakage were seen in the trachea and right bronchus on electrical stimulation of the right vagus nerve. PGE1 (1-1000 micrograms/kg) inhibited the leakage induced by capsaicin in the trachea and bronchi concentration dependently with complete inhibition at a concentration of 1000 micrograms/kg. Likewise, PGE1 (1000 micrograms/kg) significantly inhibited electrical stimulation-induced leakage in the trachea and right bronchus (P less than 0.01). I.v. substance P (SP; 1 microgram/kg) increased Evans blue dye extravasation in the same way as the leakage induced by capsaicin and electrical stimulation but PGE1 (1000 micrograms/kg) failed to inhibit SP-induced leakage in the trachea and main bronchi (P greater than 0.20). These results suggest that PGE1 inhibits neurogenic plasma leakage by presynaptic inhibition of the release of neuropeptides from sensory nerves.

[Amelioration of cisplatin-induced vomiting and anorexia by methylprednisolone].

Amelioration of cisplatin (CDDP)-induced vomiting and anorexia by methylprednisolone (MP) was studied using conscious dogs. The incidence of vomiting was 88.9% and the mean number of emetic episodes was 8.22 +/- 1.25/dog during 5 hours after i.v. administration of 1.5 mg/kg CDDP in 9 dogs. In control dogs, food intake on the day after administration of CDDP was markedly reduced to 60 +/- 22.4 g/day from 461 +/- 23 g. Continuous high-dose infusion of MP (10 mg/kg, 10 min before the start of CDDP infusion and 50 mg/kg/h for 5 h) markedly reduced the incidence (33%) and mean number of vomiting episodes (2.00 +/- 1.51/dog) and also mitigated the reduction of food intake (350 +/- 30.6 g/day). However, continuous low-dose infusion of MP (5 mg/kg, 10 min before CDDP infusion and 16.6 mg/kg/h for 5 h) showed a little effect on CDDP-induced vomiting. Plasma MP levels after the high-dose and the low-dose regimens were 6.20 +/- 0.628 micrograms/ml and 4.66 +/- 1.72 micrograms/ml, respectively, 30 min after CDDP infusion. In both cases, MP levels gradually increased and reached to those more than twice 5 hours after CDDP infusion. Bolus administrations of MP (30 mg/kg, each time) 2 hr and 30 min before CDDP infusion also significantly reduced the mean number of emetic episodes (3.22 +/- 1.33/dog) and mitigated the reduction of food intake (325 +/- 37.3 g/day). No significant changes in catecholamines, prostaglandins, vasopressin, plasma renin activity, Na+, K+, Mg++ and osmolality in peripheral blood were noted after administration of CDDP and/or MP. The results suggest that administration of MP was effective against CDDP-induced vomiting and anorexia in dogs.

Effects of qing-fei-tang (seihai-to) and baicalein, its main component flavonoid, on lucigenin-dependent chemiluminescence and leukotriene B4 synthesis of human alveolar macrophages.

A traditional Chinese remedy, Qing-Fei-Tang (Seihai-to, T90), has been used for treatment of chronic respiratory diseases with long-lasting cough and sputum, e.g. chronic bronchitis. We examined the effect of T90 and its main component flavonoid, baicalein, on the lucigenin-dependent chemiluminescence (CL) and leukotriene B4 (LTB4) synthesis of human alveolar macrophages (AM). AM were obtained by bronchoalveolar lavage from patients with various respiratory diseases, including sarcoidosis, idiopathic pulmonary fibrosis, bronchial asthma, chronic bronchitis and lung cancer. CL were observed by stimulating 1 x 10(5) AM with phorbol myristate acetate in the presence of lucigenin. LTB4 were generated by incubating 1 x 10(6)/ml AM with Ca ionophore A23187 for 30 min and determined by reverse phase high performance liquid chromatography and radioimmunoassay. T90 (0.2-2.0 mg/ml) and baicalein (0.1-100 microM) inhibited both CL and LTB4 production of AM in a dose-dependent fashion. These inhibitory effects were not due to cytotoxic effects of the procedure because neither 2 mg/ml T90 nor 100 M baicalein affected the viability of AM nor lactate dehydrogenase release from AM. These results suggest that T90 exerts its effect on inflammatory lung diseases through the anti-inflammatory action, i.e. inhibiting the oxidative and arachidonate metabolism of local inflammatory lung cells.

Late asthmatic response to Ascaris antigen challenge in dogs treated with metyrapone.

We developed an experimental dog preparation that shows a biphasic bronchoconstriction after allergen exposure. After anesthetization, the dogs were intubated with endotracheal tubes and manually ventilated. Respiratory resistance (Rrs) was measured by the forced oscillation method at 3 Hz. Ascaris suum, diluted from 10(-5) to 10(-2) of the extract, was inhaled during tidal breathing for 5 min. One hour before antigen challenge, 10 dogs received 70 mg/kg of metyrapone (cortisol synthesis inhibitor), and 2 h after antigen challenge 35 mg/kg of metyrapone were injected intravenously. In another 10 dogs, metyrapone was not administered. After the maximal increase in Rrs had been assessed (immediate asthmatic response), Rrs increased again 4 to 6 h after antigen challenge in 8 of the 10 dogs treated with metyrapone (late asthmatic response, 443 +/- 282% mean +/- SD of initial Rrs), which was significantly higher than Rrs 6 h after antigen challenge (124 +/- 41%) in dogs without metyrapone (p less than 0.01). In another 5 dogs, ragweed challenge with metyrapone caused no change in Rrs. Bronchoalveolar lavage at the time of the late response revealed a significant correlation between late asthmatic response and neutrophil accumulation (p less than 0.01) in all dogs. We conclude that cortisol depletion augments the occurrence of the late response. The present dog model may be a useful tool for study of the late response in bronchial asthma.

[The mechanism of the decrease in serum potassium during insulin-induced hypoglycemia (author's transl)].

This study was made to investigate the mechanisms of the changes in serum potassium during a period of insulin-induced hypoglycemia. The following experiments were performed: I) A relationship was observed between the amount of insulin dosage and the levels of serum potassium, blood sugar, and plasma cyclic AMP or plasma cyclic GMP in normal controls and rats. In humans, regular insulin (0.025 approximately 0.15 U/kg) was injected intravenously, and blood samples drawn at intervals were used for estimation. Regular insulin (0.1 approximately 1.0 U/kg) was injected into Wistar strain male rats and blood was drawn at intervals. II) A relationship was observed between those items mentioned above in patients with thyroid diseases or diabetes mellitus. They were injected with regular insulin (0.1 U/kg). III) An effect of spironolactone was observed on the levels of the above mentioned items. Regular insulin (0.075 U/kg) was injected into normal controls after the ingestion of spironolactone. IV) An effect of non-selective beta-blocker was observed on the levels of the above mentioned items. Regular insulin (0.1 U/kg) was injected into normal controls and patients with hyperthyroidism after the ingestion of 20 mg of propranolol. The results obtained were as follows: 1) There was a significant logarithmic dose-response relationship between insulin dose and maximum per cent decrease in serum potassium, and maximum per cent increase in plasma cyclic AMP. (p less than 0.02 approximately 0.01) 2) A significant positive correlation was observed between the maximum per cent decrease in serum potassium and the maximum per cent increase in plasma cyclic AMP during the period of insulin-induced hypoglycemia. (p less than 0.001) 3) The changes in serum potassium and plasma cyclic AMP were significantly greater in patients with hyperthyroidism who were possibly in a hyperdynamic beta-adrenergic circulatory state, and these changes were smaller in patients with hypothyroidism than in the normal controls. When their thyroid functions were normalized by the treatment, the changes in serum potassium and plasma cyclic AMP behaved in the same manner as those in the normal controls. 4) Spironolactone had no effect on any change observed in this study. 5) Neither per cent decrease of serum potassium nor per cent increase of cyclic AMP were influenced by propranolol at 15 minutes, but they decreased 30 minutes after the insulin injection. These results may indicate that a decrease of serum potassium levels during the period of insulin-induced hypoglycemia in both the early and late phases is caused by different mechanisms. The change in serum potassium was accompanied by an increase of plasma cyclic AMP, and furthermore this change was inhibited by beta-blocker. It was suggested that beta-adrenoreceptor play a role in a decrease of serum potassium, especially 30 minutes after a injection of insulin.