The Relationship Between The Dynamic Changes Of Telomeric DNA Length And Major Depression And The Establishment Of Calcium Imaging Technology

Part1 The relevant study about telomere dynamics and major depressive disorderBackgroundMajor depressive disorder(MDD), a mood correlated psychiatry disease, is usually coupled with degeneration of central nervous system(CNS), such as degradation of memory, abnormity of reward system. A large number of researches demonstrate that the telomere length of peripheral blood leucocytes(PBL) is significantly reduced, which hints that the shorten of PBL telomere length is related with morbidity of MDD. But because depression is a CNS controlled disease, it is hard to reflect the accurate relationship between PBL telomere length and CNS. So it is more essential to detect telomere length in MDD correlated brain regions. However, relevant researches about brain regions is extremely scanty, owing to the difficult postmortem. Depressive model mice,as indispensable animal tool in depression research, can compensate the drawback of clinical study.ObjectivesTo detect telomere length of depressive related brain regions, and to discuss the relationship between telomere length and depression.MethodsIn this study, three depressive animal models, CUS, CRS and SD, were established. Using real time quantitative PCR, we measured peripheral blood telomere length of these model mice. The telomere length in five brain regions of CUS mice, include hippocampus, amygdala, paraventricular nucleus, nucleus accumbens and prefrontal cortex, were also be measured. Additionally, we also detected the peripheral blood telomere length in MDD patients and healthy controls.ResultsThe peripheral blood telomere length of CUS depressive-like mice was significantly reduced(CTL n=11, T/S=1.11±0.21; CUS n=21, T/S=0.93±0.21, p=0.0295), and prefrontal cortex (CTL n=12, T/S=0.72±0.12; CUS n=22 T/S=0.87±0.13, p=0.004) and amygdala (CTL n=12, T/S=0.54±0.05; CUS n=22, T/S=0.59±0.05, p=0.011) telomere length in CUS depressive-like mice also significantly shorten than normal control; and the peripheral blood telomere length in MDD patients(n=48, T/S=2.21±0.90) also extremely shorten then healthy controls(n=505 T/S=1.12±0.50, p<0.0001).ConclusionsIt hints that CUS depressive-like mice can be used to study the relationship of depression and telomere, because of the consistent shorten trend of peripheral blood telomere in MDD patients and CUS depressive-like mice. Considering the telomere lengthen mechanisms only include telomerase and alternative lengthening of telomere that just found in some cancer cells, we inferred that telomerase activity enhanced in prefrontal cortex and amygdala. Furthermore, we considered that telomerase not only maintains telomere length, but also plays other essential role in depression.Part2 Calcium imaging of mice neurons activity in vivoBackgroundBrain as the most complicated organ, possesses many intricate neural connection and activate mode, which is a big obstacle to illuminate the brain function and the relationship between brain with mood and behavior. Fortunately, calcium imaging can be used to monitor and record neurons activity in time. It is great important in exploring brain regions and neural circuses that participate in behavior control.ObjectiveTo establish the technology platform about calcium imaging in lab, and to accomplish the recording of neural activity in vivo.MethodPacking and purifying aav-Synl-GCaMP6f-P2A-Tomato virus, and after being confirmed the recombination virus worked by infecting primary neurons, injected it into nucleus accumbens by stereotaxic injection. And after the animals recovered, the mice were implanted optical fiber in brains, and stimulated with restraint, then recorded neuronal activity in the nucleus accumbens in time. And the virus expressed brain also be sliced and imaged to verify the virus expression.ResultsAfter stimulated by glutamic acid, the neurons expressed GCaMP6f protein released green fluorescence because of the calcium influx. And after stimulating virus expressed mice, the green fluorescence signal in nucleus accumbens neurons was monitored in timely. Brain slices showed that the green fluorescence produced by GCaMP6f and the red fluorescence produced by a carried marker protein in virus could co-localize in the same neuron.ConclusionsThe adeno-associated virus aav-Synl-GCaMP6f-P2A-Tomato could be successfully used to real timely monitor activated neurons in vivo. And after expressed GCaMP6f, calcium imaging can successfully recording the activated neurons in mice nucleus accumbens under stimulation of restraint and chocolate in real time.