OBJECTIVE: To investigate the effects of resuscitation using oxygen of three concentrations on changes of cerebral intraand extracellular calcium, sodium and potassium in asphyxiated fetal rats. METHODS: Fifty-six fetal rats of twenty-day gestational age were randomly divided into five groups: sham operation (control, n=11), room-air resuscitation (n=10), and oxygen-resuscitated group Ｉ, Ⅱ, Ⅲ (n=14, 11, and 10 respectively) of different oxygen-inhaled concentrations and different oxygen timings. The fetal rats in the latter four groups suffered from ischemia and hypoxia in-uteri resulting from interruption of placental circulation. After recirculation, intra- and extra-cellular concentrations of calcium, sodium, and potassium in the brains were measured in each group. RESULTS: Intracellular free calcium concentrations of fetal rat brains in the room air resuscitation group and the oxygen-resuscitated group I (oxygen-inhaled concentration was 92.8%) were (552.08±93.50) nmol/L and (520.61±79.08) nmol/L respectively. They were similar and both significantly higher than those in the control (315.27±86.88) nmol/L (P<0.01). After resuscitation with 65% oxygen, no matter whether it started before (group Ⅱ) or at the beginning of hypoxia (group Ⅲ), their intracellular free calcium concentrations ［(441.46±47.93) nmol/L and (452.93±36.38) nmol/L respectively］ were significantly lower than those in the room-air resuscitation group (P<0.01) and group I (P<0.05), though still higher than those in the control. There was generally no difference in the total concentrations of calcium, sodium, or potassium among all groups. CONCLUSIONS: Resuscitation with oxygen of different concentrations produced different results: Resuscitation with 92.8% oxygen or room air had a similar effect on the parameters measured, indicating that resuscitation of asphyxiated neonates using pure oxygen might not be superior to that using room air; With lower cerebral intracellular calcium concentrations, resuscitation with 65% oxygen might produce a better outcome compared with that using pure oxygen or room air.
OBJECTIVE: To investigate the effects of intracerebroventricular injection of recombinant murine leptin on the food intake, body weight and blood lipids in diet induced obese rats and normal rats. METHODS: Male SD rats were put on a standard diet (n=15) and highnutrition diet (n=20) for 7 weeks. After 7 weeks, the rats received cannulas implanted into the right lateral ventricles. Allowed 7 days to recover, the rats received an intracerebroventricular injection of recombinant murine leptin (5 μg/rat) for 5 days. On each test day, the body weight and food intake were measured before the injection. Blood lipids were measured after the experiment. RESULTS: ① The body weight of the rats on the highnutrition diet was more significantly increased than that in the normal rats. At the end of the 7th week, the body weight of each group was (342.05±39.27) g and (302.87±31.93) g (P<0.01), with an increase of (270.00±39.99) g and (226.13±30.04) g (P<0.01), respectively. In the dietinduced obese rats, the inhibition of body weight and food intake was observed after the intracerebroventricular leptin injection on the 1st day, more significant on the 5th day ［body weight from (336.3±52.1) g to (287.9±53.4) g (P<0.01), and a decrease of (48.4±17.9) g; food intake from (35.6±13.7) g to (21.1±11.8) g (P<0.01), a decrease of (14.6±4.8) g］. But in the normal group, the effects were observed on the 3rd day ［body weight from (294.5±29.9) g to (269.5±30.9) g (P<0.05), a decrease of (25.0±17.8) g; food intake from (31.0±3.5) g to (25.6±3.6) g (P<0.05), a decrease of (5.3±3.3) g］. ② In the obesity group with leptin administration, the levels of TC, TG and LDL-C decreased more significantly than those in the normal control group ［TC (1.51±0.27) mmol/L vs. (2.22±0.36) mmol/L, P<0.01; TG (0.43±0.06) mmol/L vs. (0.76±0.17) mmol/L; LDL (0.47±0.12)mmol/L vs. (0.86±0.20) mmol/L, P<0.01］. But there was no obvious change of HDL-C in any of the groups. CONCLUSIONS: Recombinant leptin could reduce the body weight and blood lipids, and inhibit the food intake in dietinduced obese rats after intracerebroventricular injection, and also had a certain effect on normal rats.
