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Caffeine prevents Alzheimer’s disease in laboratory animals

Doctoral dissertation project defended at UFRGS’ Biochemistry Postgraduate Program presents the substance effects on the brain of rats
Caffeine prevents Alzheimer’s disease in laboratory animals

Caffeine had a positive effect on the animals that were prone to develop Alzheimer’s disease. Picture by: Waferboard/Flickr CC by 2.0

Author: Carolina Golenia

Janaína Espinosa Teixeira aimed at verifying whether or not caffeine may have a preventive effect on Alzheimer’s disease, using a model organism. That was the objective of her doctoral dissertation, defended at UFRGS’ Biochemistry Post Graduate Program, and advised by Lisiane de Oliveira Porciúncula - who was awarded the L’Oreal Women in Science prize for a study about caffeine as a preventive strategy against Alzheimer’s disease.

In her study, Teixeira divided a group of rats between those who would drink regular water and those who would drink water dosed with caffeine, for the course of four weeks. The rats were given the human equivalent of 3 to 4 cups of espresso coffee per day. It might seem a short period of time, however it is a substantial period considering rats’ life span. “It is as if a rat drank caffeine from the beginning to the end of its adult life”, comments Teixeira.

After those four weeks, the rats underwent an experimental brain surgery to have injected a drug that causes Alzheimer’s disease. Around the second week after surgery, the rats started to develop the disease, and memory tests were applied on them throughout that period. According to Teixeira “It was observed that the animals who had consumed caffeine, and received the drug, did not develop the disease, while those who had not consumed caffeine and received the drug did”.

It was observed that the group of rats that had consumed caffeine, but did not receive the drug did not present better results, compared to those who had drunk water only. “ We observed that caffeine only had a positive effect on the rats prone to develop Alzheimer’s disease, while it had no effect on healthy rats”, says the researcher.  Thereof , it was observed that caffeine is preventive in cases of injury or damage, not improving memory, only preventing its decay.

After this phase, the rats were euthanized and their brains were analyzed under the microscope. Those rats who underwent the surgery and had not consumed caffeine presented extensive loss of neurons in the hippocampus, which is the brain region responsible for memory, while the rats who had consumed caffeine did not present significant loss of neuron cells.

This is considered a prevention study because caffeine ingestion happened four weeks before the disease. If dementia had been induced and then treated with caffeine, this would be a reversal process. “We are investing on it because the damage caused by Alzheimer’s disease is very aggressive, and there is no drug capable of curing or reversing it so far. The only option we have nowadays is to slow down its progression, and even that is not permanent”, stresses Teixeira.

She calls attention to an interesting aspect of her study:  the model used. There are many ways of inducing Alzheimer’s disease on rats, such as creating a transgenic mouse that is mutated from birth to develop the degenerative disease later in life. In her study, Teixeira used a model organism based on suppressing insulin in the brain.

Insulin is a hormone responsible for capturing glucose from the cells; however, the brain does not need glucose for nutrition. The role of insulin in the encephalon is to help forming memories. Teixeira explains that other studies’ results showed   that people with Alzheimer’s disease have less insulin in their brain. Hence, it has been suggested that Alzheimer’s disease could be a kind of ‘brain diabetes’, or ‘type3 diabetes’. The drug injected in the rats’ encephalon destroys the insulin hormone, causing dementia.  “Then, we observed that caffeine prevented damage to the memory caused by insulin suppression in a model organism.”, she emphasizes.

The researcher points out that the hormone is injected directly into the brain because in this way it does not spread through the whole organism due to a barrier preventing the hormone from doing so. Thus, the animal will not develop diabetes since the same hormone is used to induce diabetes in rats when injected in their bellies. Other effects derived from caffeine consumption, such as psychostimulant ones, were not observed in this study, as the caffeine consumption happened in a longer period of time. Teixeira reminds us that “caffeine is a good substance for healthy people, but those who present hypertension should consult a physician before consuming it”.

When asked about carrying out the same study in humans, Teixeira explains that each person has his/her own home and routine, as well as his/her  eating habits, which makes it difficult to control the level of caffeine consumption. In addition, there is a high variability among the population, which would demand a long time to cover and some people would give up halfway through the study. On the other hand, as there is less variation among model organisms, the study can be more easily controlled, and it also takes less time to be carried out.

 

Doctoral Dissertation

Title: Neuroproteção por cafeína em modelo animal de Doença de Alzheimer

Author:  Janaína Espinosa Teixeira

Advisor: Lisiane de Oliveira Porciuncula

Department: Postgraduate Program in Biological Sciences: Biochemistry

 

Translated by Ana Nachtigall under supervision and revision of Professor Márcia Moura da Silva (UFRGS)

Original text in Portuguese is available at: http://www.ufrgs.br/secom/ciencia/consumo-de-cafeina-previne-doenca-de-alzheimer-em-animais-de-laboratorio/

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