1. Understand the preparation method of animal model of hepatic insufficiency.

2. To understand the role of phenylethylamine in the occurrence of hepatic encephalopathy and explore its rescue measures.

3. Observe the symptoms of hepatic encephalopathy.

4. Learn local anesthesia surgery.

Two. Experimental principle

Hepatic encephalopathy (He, also known as hepatic coma) is secondary to severe liver disease and neuropsychiatric syndrome. At present, it is believed that it is mainly caused by brain tissue metabolism and dysfunction, and the specific situation is still unclear. The main hypotheses are: amine poisoning theory, pseudo-transmitter theory, plasma amino acid imbalance theory, γ -aminobutyric acid theory and comprehensive theory. This experiment is designed according to the second hypothesis.

Aromatic amino acids in food produce phenylethylamine or tyramine under the action of intestinal decarboxylase. These biogenic amines are absorbed by the portal vein and enter the liver. When the liver function is normal, they can be decomposed and disinfected by monoamine oxidase in the liver.

When the liver function is damaged, these amines enter the central nervous system from the blood and generate phenylethylamine or carboxyphenylethylamine under the action of non-specific β -hydroxylase in brain cells. They are analogues of norepinephrine and dopamine, which can competitively replace normal neurotransmitters, but their effects are weak, leading to nerve conduction disorder and coma.

Three. Experimental drugs and instruments

Circular or angular suture needle, catheter beaker, gauze piece syringe (2ml, 10ml, 50Ml), corneal stimulation needle, pupil measuring ruler, thick cotton thread, arterial sleeve tension sensor, blood pressure sensor and computer biological signal acquisition and processing system.

1% saline procaine solution 1% acetic acid solution 2.5% phenylethylamine solution 2.5% levodopa solution ether heparin (500U/ml)

Four. subject

Two rabbits

Verb (abbreviation of verb) experimental steps

1. After loading, anesthetize the rabbit with ether and fix it on the rabbit operating table. After waking up, the neck was anesthetized with 1% normal saline procaine solution for tracheal intubation and arterial intubation, and the blood pressure sensor was connected with the biological signal system to record the blood pressure changes.

2. Cut off the rabbit hair in the middle of abdomen, and use 1% saline procaine solution for local infiltration anesthesia. Cut the middle of the upper abdomen (about 6-8cm long) from the xiphoid process of the sternum, cut the abdominal cavity along the white line of the abdomen, extend the index finger and middle finger to the hepatic diaphragm, separate the two sides of the sickle ligament and press down the liver, expose and break the sickle ligament between the hepatic diaphragms with your fingers, and then peel off the hepatogastric ligament with your fingers to free the liver.

3. Turn the liver and pancreas upside down, carefully identify each liver lobe, tie the root around the left outer lobe, left middle lobe, square lobe, right middle lobe and tail lobe (leaving the right outer lobe) with thick cotton thread, and then cut along the line after the liver lobe turns from red to brown.

4. Cut off the cartilage stalk of xiphoid process and free xiphoid process. Hook the xiphoid cartilage with a hook, and connect the tension sensor at the other end. The tension sensor will transmit the signal to the biological signal acquisition and processing system to record the respiratory movement.

5. Find the duodenum along the pylorus of the stomach, insert the catheter connected with the syringe into the right side of the small intestine, ligate and fix it, and close the abdominal cavity.

6. Observe and record the general situation of rabbits, including respiration, blood pressure, corneal reflex, pupil size and response to pain stimuli.

7. Inject 5ml of 2.5% phenylethylamine solution into duodenum every 5-7min, and closely observe the changes of breathing, corneal reflex, pupil size, response to pain stimuli, muscle tension, etc. of rabbits until spasm occurs. Record the breathing, blood pressure, corneal reflex, pupil size and response to pain stimulus at this time, record the time and total dose from administration to completion, and get the unit dose.

8. Therefore, 2.5% levodopa was injected into peripheral vein for rescue, and 5ml/Kg of 1% acetic acid was injected into duodenum at the same time, and the effect was observed.

9. Another rabbit with similar weight and the same sex was taken as the control, and the rest were the same as above.

Prediction of experimental results of intransitive verbs

1. Compared with the experimental group, the hepatic coma reaction is not obvious and the rescue effect is good.

Levodopa does have therapeutic effect on hepatic encephalopathy.

3. phenylethylamine can cause hepatic coma, which proves that patients with liver disease should eat less animal protein and more plant protein (because BCAA/AAAAA 1).

Seven. preventive measure

1. In this experiment, the dose, whether hepatic coma can occur in time and how long after administration are not clear.

2. The first step, mild anesthesia with ether, and then fixed. Ether may make a hypothesis for this experiment, but I don't know any better way to correct it directly.

3. The third step only causes liver dysfunction, so which one to keep and whether to remove it are optional.

4. The fixation in the fourth step can be fixed by suture purse or similar tracheal intubation.

References:

Wang pathophysiology science press.

Liu Feng Pathophysiology Experimental Guide Military Medical Science Press

Yang Pan Wu Weikang Advanced Pathophysiology Science Press.

Clinical analysis of 74 cases of liver cirrhosis complicated with hepatic encephalopathy in Wang Yu: full-text database of excellent doctoral and master's dissertations in China

Input "pseudo transmitter" and "phenylethylamine" into "China Journal Network Mirror Station" and "VIP Chinese Sci-tech Journals Full-text Database", but failed to find useful related information.

At present, the research on hepatic encephalopathy mainly focuses on clinical treatment, medical record analysis and the influence of toxins.