Objective To investigate the effects of chronic pain on spatial learning ability and the expression of neuronal cell adhesion molecules (NCAM) in hippocampus in neonatal rats.Methods Sixty newborn SD rats of both sexes were randomly divided into pain group ( n = 30) and control group ( n= 30). In pain group complete Freund' s adjuvant (CFA) 20 ?l was injected subcutaneously in the plantar surface of left hindpaw on the 2nd day after birth, whereas in control group normal saline 20 ?l was injected instead of CFA. The animals were weighed on the 3rd, 11th and 22nd day after birth. Ten animals in each group were anesthetized with intraperitoneal pentobarbital and killed on the 11th and 22nd day after birth respectively. The brains were immediately removed for determination of NCAM expression in CA3 and dentate gyms of hippocampus using immuno-histochemical staining technique. Morris water maze test was performed starting from the 21st day after birth for 8 consecutive days to assess the spatial learning ability ( n = 10 in each group) .Results The latent period before finding the hidden-plateform was significantly longer on the 1st and 4th day of the test (22nd and 25th day after birth) in pain group than in control group (P

Objective To investigate the effects of chronic inflammatory pain induced by injection of complete Freund' s adjuvant (CFA) into the plantar surface of hindpaw on the development of learning and memory and proenkephalin mRNA expression in hippocampus of neonatal rats. Methods sixty neonatal SD rats (6 rats from each of 10 litters) were randomly divided into control and chronic pain group ( n = 30; 3 rats from each of the 10 litters). In chronic pain group CFA 20 ? l was injected subcutaneously into plantar surface of left hindpaw on the 2nd day after birth whereas in control group normal saline 20 ? l was injected instead of CFA. Ten animals (1 rat from each of the 10 litters) in each group were killed on the 10th and 21st day after birth respectively. Hippocampi were removed for determination of proenkephalin mRNA expression by RT-PCR. Ten animals (1 rat from each of the 10 litters) in each group underwent Morris water maze test 3 times a day for 8 days starting from the 21st day after birth. Results The mean latent period before the rats found the hidden platform was significantly longer in chronic pain group than in control group. When the platform was removed the swimming time and distance of the rats in chronic pain group were significantly shorter than those in control group. There was no significant difference in the latent period before the rats found the visible platform between the two groups. The proenkephalin mRNA expression in hippocampus on the 10th and 21st day after birth was significantly lower in chronic pain group than in control group ( P

Objective To determine the optimum dose of pentazocine when combined with propofol for gastroscopy in elderly patients.Methods One hundred and forty ASA physical status Ⅰ or Ⅱ patients,aged 6575 yr,scheduled for elective gastroscopy under general anesthesia,were randomly assigned into Ⅰ-Ⅳ groups (n =35 each) using a random number table.Before insertion of the gastroscope,pentazocine 0.2,0.4 and 0.8 mg/kg were injected intravenously in Ⅱ-Ⅳ groups,respectively,while the equal volume of normal saline was given in Ⅰ group.Propofol was then administered by target-controlled infusion (TCI).The half-effective concentration (EC50 of propofol was determined by up-and-down sequential trial.The target plasma concentration (Cp) was set at 3.5 μg/ml in the first patient.Gastroscopy was performed at 5 min after the target effect-site and plasma concentrations were balanced.The response to gastroscopy was defined as positive when body movement and/or bucking occurred during gastroscopy.Each time the Cp increased/decreased by 0.3 μg/ml in the next patient depending on whether or not the response to gastroscopy was positive.EC50 and 95 ％ confidence interval of propofol TCI inhibiting the response to gastroscopy were calculated using Probit analysis.The development of respiratory depression and hypotension was observed.Results EC50 (95 ％ confidence interval) of propofol TCI inhibiting the response to gastroscopy was 2.82 (2.63-3.02) μg/ml,2.78 (2.58-2.97) μg/ml,2.16 (2.00-2.32) μg/ml and 2.03 (1.88-2.19) μg/ml in Ⅰ-Ⅳ groups,respectively.Compared with group Ⅰ,EC50 was significantly decreased in Ⅲ and Ⅳ groups,and the incidence of respiratory depression was increased in Ⅳ group (P ＜ 0.05).Conclusion The optimum dose of pentazocine when combined with propofol is 0.4 mg/kg for gastroscopy in elderly patients.