Effects of avoidance experiment and open field experiment on memory behavior of aged mice

Effects of avoidance experiment and open field experiment on memory behavior of aged mice

Abstract: The open field model and model disposable passive avoidance response in aged mice were treated with hyperbaric oxygen spontaneous activities detected and memory retention, lipofuscin and brain spectrophotometer fluorescent discussed hyperbaric oxygen ( The effect of HBO on aging learning and memory impairment and its relationship with lipofuscin content in the brain . The results show that : (1) Hyperbaric oxygen can significantly enhance the spontaneous activity of aged mice in new environments, and significantly improve their memory retention. force; (2) so that hyperbaric oxygen lipofuscin in aged mice brain hyperbaric oxygen content decreased suggesting can improve age-related memory disorders, which may be related to decreased brain lipofuscin content related.

Key words : hyperbaric oxygen ; opening behavior ; one-time passive avoidance reaction ; lipofuscin

Hyperbaric oxygen (hyp e rba r ico xygen, HBO) has been widely used as a non-invasive method for the treatment of brain diseases , such as cerebral ischemia, craniocerebral injury, persistent vegetative state, Alzheimer's disease and vascular dementia. treatment of diseases, to restore brain function have a good effect, however, about the hyperbaric oxygen effect on normal physiological aging is rarely reported. the author previous experiments showed that hyperbaric oxygen may improve age-related memory disorders, and reduce the Calcium levels in synapses in the main brain regions ( cerebral cortex, hippocampus, cerebellum, and diencephalon ) related to learning and memory . Considering the causes of brain aging , the accumulation of lipofuscin in the brain leads to damage and function of brain cells. One of the reasons for the decline , therefore , the author observed the effect of hyperbaric oxygen on aging memory impairment and lipofuscin content in the brain , and explored the mechanism of hyperbaric oxygen on aging learning and memory behavior .

1 Materials and methods

1. 1 experimental animal

The Kunming strain of aged (18 months old ) mice , weighing (35 ± 3) g, both male and female , was provided by the Animal Center of Nanjing College of Traditional Chinese Medicine .

1. 2 high pressure oxygen treatment

The mice were randomly divided into normal pressure oxygen group (0. 10M P a) , hyperbaric oxygen group (0.25 M P a) and control group . The experimental group animals entered self-braking.

In the pressurized oxygen chamber , the chamber is fully washed with medical pure oxygen for 10m in, and the hyperbaric oxygen group is gradually pressurized to 0.25 MP a, staying at 60m in high pressure , then decreasing to normal pressure at 20m in constant pressure ; atmospheric oxygen under normal pressure in the suction group (0. 10M P a) pure 60m in. for 1h per day, for two weeks. regular feeding control group of mice.

1. 3 behavior test

(1) Opening experiment, open field experiment

Observe the second day after the last hyperbaric oxygen treatment . The bottom surface of the opening environment is divided into a number of cells . The instrument model is XR-XZ301, and the number of cells that the mouse runs through the center of the bottom surface within 3 m in (the first 1 m is recorded). number of cells in the running in), rears (including free-standing stand and buttresses) times, grooming and defecation. HBO Comparative test group and control group of mice in a novel environment spontaneous behavior in the performance Difference .

(2) One-time passive avoidance reaction , avoiding dark experiment

This model was used to test the memory retention of mice . According to the darkening habits of mice , the time to stay on the channel before entering the dark box , ie step 2th ro ugh la tency (STL); the animal entered the dark box and received an electric shock. The STL was measured 24 h after (0. 3 mA, 50 H z, 5 s) . The longer the STL , the better the memory retention of the electric shock was . The detection time was limited to 300 s .

1. 4 brain tissue lipofuscin content determination

After decapitation behavior detecting sections of brain, deionized water, and T ef lo n homogenized with a glass homogenizer, added with chloroform methanol 2 (2:1) was thoroughly shaken, 1 500 röm in centrifugal 10m in , and the lower layer organic phase was fluorescent photometer R F2540 fluorescence intensity (emission wavelength 435nm, excitation wavelength of 365 nm), to 1m göL quinine sulfate standard was calculated lipofuscin content per gram fresh brain tissue.

1. 5 statistical processing

Statistical analysis of opening behavior and lipofuscin content data , using inter-group t- test ; one-time passive avoidance response using Mann2

W h itney nonparametric test . The effect of Shanghai Xin soft avoidance experiment and open field experiment on memory behavior of aged mice

2 results

2. The effect of hyperbaric oxygen on the opening behavior of mice

The results are shown in Table 1. Compared with the control group , hyperbaric oxygen increased the number of running cells in the opening environment , especially in the first m in the running number of the control group (P < 0.01). ), the number of hind legs standing increased significantly (P < 0.001). It indicates that hyperbaric oxygen can increase the excitability of the central nervous system in aged mice , and its spontaneous activity and inquiry behavior in the new environment are significantly increased .

2. 2 Effect of hyperbaric oxygen on one-time passive avoidance response behavior in mice

Table 2 data show no significant effect of hyperbaric oxygen on step-through latency (STL) before the shock aged mice, but that the shock after 24h of STL significantly prolonged compared with the control group, the difference was significant (respectively P <0. 05 and P < 0. 01). It shows that hyperbaric oxygen can significantly improve the memory retention ability of aged mice . The effect of Shanghai Xin soft avoidance test and open field experiment on memory behavior of aged mice

3 Discussion

In the process of aging of animals , the structure of the nervous system, especially the brain , changes with age. The accumulation of lipofuscin in the brain is one of its important morphological indicators . The lipofuscin mainly accumulates in the cerebral cortex and hippocampus. previous studies showed that aged mice with impaired learning lipofuscin elevated brain and memory function. excessive accumulation of lipofuscin, a phospholipid breakable membrane structure, resulting in reduced mitochondria and rough endoplasmic reticulum And changes in subcellular structure such as vacuolization , and the number of neurons is reduced , resulting in a decline in learning and memory . Hyperbaric oxygen can greatly increase the amount of physical dissolved oxygen and blood in the blood.

Oxygen tension , increase the oxygen supply of brain cells , make aerobic metabolism strong , improve brain cell metabolism and nutrition , promote brain cell division and proliferation , and help brain damage repair ; at the same time , hyperbaric oxygen causes intracranial artery contraction , vascular resistance increases , The blood pressure is reduced , and the intracranial pressure is decreased . Therefore , the hyperbaric oxygen therapy has been used as an important first-aid method for cerebral resuscitation , and the pressure range of the treatment is mostly at 0. 15M P a ～ 0. 25M P a.

After this experiment aged mice hyperbaric oxygen treatment, it was found by 0. 10M P a 0. 25M and P a locomotor activity of aged mice treated in a novel environment significantly increased memory retention were significantly improved. On the other Correspondingly , the content of lipofuscin in the brain of aged mice after hyperbaric oxygen treatment decreased significantly , suggesting that the mechanism of hyperbaric oxygen to improve aging memory impairment may be related to the reduction of lipofuscin content in the brain . Studies have shown that animals in the process of aging The accumulation of lipofuscin in the brain is related to the disorder of free radical metabolism in the body . The large amount of free radicals generated during aging exceeds the body's ability to scavenge , triggering a chain reaction of lipid peroxidation , leading to cell membrane damage , and at the same time , lipid peroxides. (L PO) decomposition end products ( such as M DA) can be combined with DN A , RN A , protein and phospholipids to change the membrane composition , dysfunction , and promote the body's aging process . The metabolic end products of lipid peroxidation can cause mental and behavioral changes, and by cross-linking, to form lipofuscin, causing dysfunction of the nervous system and can increase the in vivo hyperbaric oxygen free radical scavengers - the activity of superoxide dismutase (SOD), inhibit Lipid peroxidation, block free radical chain reaction. These results suggest that the mechanism of hyperbaric oxygen aged animals improved cognitive function may be relevant, and thereby inhibit the accumulation of lipofuscin in the brain, so the brain tissue damage and termination Gradually repairing , thus improving the memory function of the brain . The effect of Shanghai Xin soft avoidance experiment and open field experiment on the memory behavior of aged mice