Expression Of The Cβ Catalytic Subunit Of Protein Kinase A In The Lateral Dorsal Thalamic Nucleus Of The Rat During Learning And Memory

Objective: The lateral dorsal thalamic nucleus(LD) is an important part of the dorsal thalamus, which is located in the dorsal lateral of the thalamus. It is composed of laterodorsal dorsomedial nucleus(LDDM) and laterodorsal ventrolateral nucleus(LDVL). Studies had shown that the lateral dorsal thalamic nucleus associated with spatial learning and memory, involving spatial reference memory and spatial working memory. Protein kinase A(PKA), called cyclic-AMP dependent protein kinase A, plays an important role in the signal transduction of learning and memory. In the experimental study, we use Morris water maze ethological experiment,immunohistochemistry(IHC) and western blot to observe the expression and distribution of PKA-Cβ in the lateral dorsal thalamic nucleus of rats. I hope the results can provide a theoretical reference for lateral dorsal thalamic nucleus participating in the learning and memory function.Methods: In this experiment, we choose forty adult, male wistar rats, weighed200~250g, divided into experimental group and control group. The two groups were asked four days’ place navigation test and one day’s spatial probe test. In the test, the rats of experimental group were placed in the water maze with platform for the spatial learning and memory training, but the rats of control group were trained without the platform. Then the rats were anesthetized with ether and 4 % chloral hydrate intraperitoneal and got the operation of the heart perfusion and the brain remove in 2hours after the spatial probe test(In Western Blot,we only use 0.9%normal saline to perfusate). In the immunohistochemical test, the brains were fixed with 4%paraformaldehyde for one day and sliced to the 30μm-thickness sections. Using the anti-PKA-Cβ antibody as the marker, we observe the expression and distribution of PKA-Cβ. In western blot, we extracted the protein of the lateral dorsal thalamic nucleus tissue, did the SDS-PAGE electrophoresis, then transfered to the PDVFmembrane.Using PKA-Cβ as the target and the β-actin as the reference, we did the chemiluminescence staining and analysis of imaging. The comparision between groups is using two independent samples t test, and the comparision within the group is using the paired t test. The comparision of the escape latency of the different days in water maze behavioral experiments is using single factor analysis of variance.Results: 1.Morris water maze behavioral test result: In the place navigation test, the average escape latency of the experimental group became gradually shortening with the training days increasing. The differences among the different day’s training were significant(P < 0.05) except the difference between the secong day’s and the third day’s(P>0.05). And the difference between the escape latencys of the fourth day’s place navigation test and the fifth day’s Spatial probe test is not significant(P>0.05).2. Immunohistochemical results: the expression of PKA-Cβ was located within the nucleus and nerve fibers in the lateral dorsal thalamic nucleus. With the analysis of the optical density values of the immunoreactive products, the difference between the experimental group and the control group is significantly(P < 0.05). But the difference between the expression of PKA-C β in LDDM area and the LDVL area in experimental group was not significant(P>0.05).3. Western blot result :In the lateral dorsal thalamic nucleus, the expression of PKA-C βin experimental groupwas higher than that of control group(P <0.05).Conclusion: In the process of learning and memory, the expression of PKA-Cβ in the lateral dorsal thalamic nucleus was increased in the establishment of learning and memory’s rat, which explain that the changes of PKA-Cβ is related to the mechanism of LD’s participating in spatial learning and memory.