Effects Of Naloxone On The Learning And Memory Functions In Rats With Sub-acute Alcoholism And Stress

Objective: To prepare the model rats with sub-acute alcoholism under stress and toobserve the intervention of naloxone on the learning and memory functions of thosemodel rats.Methods: Sixty-two Sprague-Dawley male rats were randomly divided into six groups:Control group (C, n=11), Normal Saline group (NS, n=6), Naloxone group (N, n=11),Stress group (St, n=11), Sub-acute alcoholism group (SA, n=11), Sub-acute alcoholismand stress group (St+SA, n=12). After adaptive feeding, the model was made. The"sound-shock" paired stimulation was given by St and St+SA group in rats for3daysafter adaption of shock box at the first day without stimulation. The rats of St and St+SAgroup were put into the shock box at the5thday without stimulation to detect thefreezing reaction time. After the stress, rats of SA group and St+SA group were fed inalcohol for10days at a dose of15ml/kg, the5%concentration of alcohol solution weregiven by SA group and St+SA group in rats at the first day, on the basis of the first day,the5%concentration of alcohol solution was increased every day. The35%concentration of alcohol solution was kept from the7thday. The dose of saline as muchas rats of St and St+SA group were given by rats of NS. The freeze monitor was used todetect the stress in rats, the open-field test was used to observe the activity of rats beforeand after alcohol intake, and the Morris water maze was used to examine effects ofnaloxone on the learning and memory functions in rats with sub-acute alcoholism under stress.Results:1. The comparison of freeze monitor resultsThe comparison of freeze monitor in rats before and after the stress, alcohol intakeand after the intervention of naloxone was performed by two-way ANOVA (repeatedmeasures) among groups. The results showed that F(3,168)=12.53, P<0.001for testeddays, and F(5,56)=13.60, P<0.001for groups; St and St+SA group and other groupswere significantly different (P <0.05).The comparison before and after stress in rats, St group (t=-8.28, P<0.001) andSt+SA group (t=-6.62, P<0.001) were both significantly different before and after stressby freeze monitor. The comparison of C group and St group (t=-7.52, P<0.001), Cgroup and St+SA group (t=-5.19, P<0.001), and SA group and St+SA group (t=-2.43,P<0.05) showed significant differences before and after stress in rats.The comparison before and after alcohol intake in rats presented N group (t=-3.89,P<0.001), St group (t=4.48, P<0.001), St+SA group (t=2.27, P<0.05) were significantlydifferent. C group and NS group before alcohol by gavage (t=-0.12, P>0.05) and afteralcohol by gavage (t=-0.56, P>0.05) were not remarkably different.The comparison after the intervention of naloxone in rats, the comparison amongsix groups of rats was statistically different (F=3.50, P<0.01). N group, St group andSt+SA group were compared with other groups and had differences significantly(P<0.05).2. The comparison of open-field test resultsAfter alcohol feeding the central cell residence time（F=2.36, P<0.05）, the totalnumber of crossing cells（F=7.04, P<0.001）, stand-up times（F=8.56, P<0.001）of theopen-field in rats among six groups were significantly different, but modified times andfecal grains (P>0.05) were not different. By the comparison of SNK-q, the total numberof crossing cells of C group, SA group and St+SA group compared with other five groups was P<0.05, N group compared with other four groups without St group wasP<0.05, St group compared with other four groups without N group was P<0.05.The stand-up times of C group, N group and St group compared with SA groupand St+SA group were P<0.05. Before and after alcohol feeding all of rats wereexamined by the open-field test, the total number of crossing cells (t=9.37, P<0.001),stand-up times (t=6.68, P<0.001), modified times (t=-5.05, P<0.001), and fecal grains(t=2.26, P<0.05) had significant differences. The central cell residence time (t=3.31,P<0.01), the total number of crossing cells (t=2.60, P<0.05) and stand-up times (t=3.49,P<0.01) between C group and SA group were significantly different.3. The comparison of Morris water maze test resultsTwo-way ANOVA (repeated measures) analysis of the escape latency of six groupsin the place navigation test at7days showed F(6,336)=23.15, P<0.001for test days,F(5,56)=1.34, P>0.05for animal groups, and F(1,56)=594.84, P<0.001for theinteraction between test days and groups, while NS group and St+SA group weresignificantly different (P<0.05). By using one-way ANOVA, escape latency of rats at7days with each group was analyzed, and the results presented C group (F=6.19,P<0.001), NS group (F=4.77, P<0.001), N group (F=6.96, P<0.001), St group (F=4.77,P<0.001), SA group (F=1.14, P>0.05), St+SA group (F=3.32, P<0.01). The comparisonof escape latency between C group and SA group was significantly different (t=2.32,P<0.05) at the4thtest day during the place navigation test.Chi-square test among rats at7days of the ratio of strategic analysis showedχ2=867.20, P<0.001for Day1, χ2=898.70, P <0.001for Day2, χ2=666.30, P<0.001forDay3, χ2=825.70, P<0.001for Day4, χ2=108.90, P<0.001for Day5, χ2=932.80,P<0.001for Day6, χ2=675.40, P<0.001for Day7.Two-way ANOVA (repeated measures) analysis of swimming speed showed asignificant difference (F=19.19, P<0.001) among7days in the place navigation test,while F=3.25, P<0.01among six groups at the5thday, and the swimming speed of each group were declined during the7-day place navigation test. The six-day swimmingspeed of C group and SA groups was statistically significance (F=-2.68, P<0.05), thefive-day swimming speed of C group and St+SA groups was also statisticallysignificance (F=2.45, P<0.05).The time ratio in target quadrant of C group at the four-day compared with SAgroup (t=2.13, P<0.05) and St+SA group (t=2.18, P<0.05) was of significancestatistically, respectively. The time ratio in target quadrant at the six-day in placenavigation test between N group and St+SA group was significantly different (t=2.25,P<0.05).The comparison of the number of crossing plate between NS group and N group inthe spatial probe test was significantly different (t=2.34, P<0.05).4. The comparison of body weight in rats with each groupEach group of rats was analyzed by Two-way ANOVA (repeated measures) beforeand after the stress, alcohol intake and after the intervention of naloxone, the bodyweight of the model rats compared with C group was significantly decreased (P<0.05),and the differences of body weight among groups were significant, F(5,56)=11.71,P<0.001; while F(4,224)=213.80, P<0.001for test days. Using the SNK-q pairwisecomparison of the body weight, differences between C group, N group and St comparedwith NS group, SA group and St+SA group compared with other groups weresignificant (P<0.05). However, the body weight between SA group and St+SA groupwas not significantly different (P>0.05).Conclusions: The activity and body weight of rats are suppressed by alcohol intake.The learning and memory functions of model rats with sub-acute alcoholism understress are damaged. Naloxone has some improvement on model rats with sub-acutealcoholism under stress.