ABSTRACT
BACKGROUND: Autophagy is a homeostatic process for intracellular recycling of bulk proteins and aging organelles. Increased autophagy has now been reported in experimental models of traumatic brain injury, stroke and excitotoxicity, and in patients with Alzheimer's disease and critical illness. The role of autophagy in developmental epilepsy, however, is unknown. The present study was to investigate the effects of recurrent neonatal seizure, in the presence and absence of autophagy inhibitor 3-methyladenine (3-MA), on the acute phase gene expression of ZnTs, LC3 and Beclin-1 in rat cerebral cortex and the interaction among them. METHODS: Thirty-six Sprague-Dawley neonatal rats at postnatal day 6(P6) were randomly divided into three groups: a recurrent-seizures group (RS, n=12), a 3-MA treated-seizure group (3-MA group, each rat pretreated with 3-methyladenine before seizures, 100nmol/ l/day, i.p., n=12) and a control group (n=12). At 1.5 and 6 hours after the last seizures, the mRNA levels of ZnT1-ZnT3, microtubule-associated protein 1A/1B light chain 3 (LC3) and beclin-1 were detected using the real-time RT-PCR method. The LC3 protein level was examined by Western blotting. RESULTS: The levels of LC3, beclin-1 and ZnT-2 transcripts in the RS group elevated significantly at 1.5 and 6 hours after the last seizures compared with those in the control and 3-MA groups. At the interval of 1.5 hours, the mRNA level of ZnT-1 increased significantly after the last seizure compared with that in the control group. There was no significant difference in the transcript levels of ZnT-3 among the three groups. Linear correlation analysis showed that the expression of the five genes in the control group exhibited a significant inter-relationship. In the 3-MA group, however, the inter-relationship was only found between beclin-1 and ZnT-1. In the RS group, the inter-relationship was not observed. CONCLUSIONS: The autophagy/lysosomal pathway is immediately activated along with the elevated expression of ZnT1 and ZnT2 in the cerebral cortex after recurrent seizures. 3-MA is involved in the regulation of the autophagy/lysosomal pathway and ZnTs by down-regulating the expression of LC3 and beclin-1.
ABSTRACT
Objective To explore the effects of physical exercises on recurrent seizures-induced long-term learning and memory deficits and on the expression of zinc transporter-3(ZnT-3)in hippocampuses of developmental period rats.Methods Sprague-Dawley rats aged 21 d were randomly divided into blank control group,exercises control group,seizure group and seizure plus exercises group.Abdominal cavity injections of penicillin or saline were used to induce recurrent seizure or as a control in the corresponding groups.During the postnatal(P)39-44 d and P61-65 d periods,Morris water-maze tests were administered to evaluate spatial learning and memory capacity.During the P48-53 d period,the rats in exercises control and seizure plus exercises groups were subjected to a 30-min daily aerobic exercises program for 6 d.The real-time reverse transcription-polymerase chain reaction(RT-PCR)method was used to detect the expression of ZuT-3 mRNA in hippocampuses of all rats at P66 d. Results Searching strategy:There was a decreasing incidence of marginal strategy and an increasing trend in the use of taxis and straight line strategy in all four groups.The scores on d 1 and 4 were significantly higher in two control groups than in two seizure groups in water-maze test(all P＜0.05).By d 2 the exercises control and seizure plus exercises groups were scoring significantly higher than the bland control and seizure groups(P＜0.05).Memory test:The frequency of passing through the platform quadrant decreased significantly in the two seizure groups compared to the two control groups in both probe tests(all P＜0.05).RT-PCR test:ZnT-3 mRNA expressions in hippocampuses were significantly higher in seizure plus exercises group than in any other groups. Conclusions Penicillin-induced recurrent seizures can induce long-term damage on learning and memory capacity in developmerital period rats.Physical exercises can improve learning capacity.It's mechanism may be related to the up-regulation of ZnT-3 expression in hippocampus of rats.
ABSTRACT
Objective:To observe the growth and development of the weaned mice fed with different levels of dietary zinc and to explore the expression of zinc transporter 3(ZnT3) mRNA induced by different dietary zinc intakes. Methods: Twenty male weaned mice (postnatal day 21) were divided into 4 groups: zinc deficient (ZD), zinc adequate(ZA), zinc supplemental (ZS) and pair fed(PF). Mice were fed with different levels of dietary zinc for 3 weeks (from postnatal day 21 to postnatal day 42) ;the zinc contents of ZD, ZA, ZS and PF group were 1 mg/kg, 30 mg/kg, 180 mg/kg and 180 mg/kg respectively. From postnatal day 21 to postnatal day 42, the diet intakes and weight of the mice were measured everyday. On postnatal day 42, the mice were sacrificed and tissues were immediately isolated and frozen lor RNA extraction. The serum zinc concentrations were measured by AAS and the expression of ZnT3 mRNA was determined by semiquantitative RT-PCR. Results: The dietary intakes and weight of ZD mice were much lower than that of other groups(P3