Rebekah Eliason for redOrbit.com – Your Universe Online
Feelings of happiness are triggered by the neurotransmitter dopamine in the brain. A few of the common triggers for dopamine release are food, sex and drugs. Once the brain receives a dose of dopamine, it is not content with a onetime burst of joy but instead remembers the feeling and works to achieve it again and again. Dopamine enables us to remember how to make decisions that once again give us that happiness kick.
Researchers working at the Department of Biosystems Science and Engineering (D-BSSE) in Basel, Switzerland recently discovered a new therapy using the dopamine system. This work, headed by ETH-Zurich professor Martin Fussenegger, lead to the development of a new genetic module which can be controlled by dopamine. The module is activated by the feel-good molecule but is dependent on the dosage. If there is an increase of dopamine in the blood stream, the module responds by producing the active agent.
This specific module is composed of different biological parts interconnecting with one another to produce a synthetic signaling cascade. At the very beginning of the cascade, dopamine receptors are found and function as sensors. The end product is one of two proteins known as SEAP or ANP, which are vasodilators that lower blood pressure. Researchers inserted these signal cascades into human cells and approximately 100,000 were put into capsules. These special capsules were then implanted into mice abdomens.
After injection of the capsules, the mice were exposed to situations such as sexual arousal, triggered by a female mouse in males, the drug methamphetamine, or golden syrup; all of which were designed to correspond with the central reward system that produces dopamine. When the mouse brain responded by creating a “state of happiness,” dopamine was formed and released into the blood by the peripheral nervous system.
Some mice were given varying concentrations of golden syrup so that the happiness level varied. When the sugar was more diluted, less dopamine was produced which caused less of the active agent to circulate in the blood. According to Fussenegger, “This shows that dopamine does not merely switch our module on and off, but also that it responds based on the concentration of the happiness hormone.”
The researchers also designed a dopamine sensor module to produce the antihypertensive agent ANP and placed it in the abdomens of hypertensive male mice. When the male mice came in contact with a female mouse, enough dopamine was released to trigger ANP production that entirely corrected the hypertension and even caused the blood pressure to normalize.
The results of this research showed that dopamine is not only released in the brain in response to feel-good situations but also in the nerves of the sympathetic nervous system, also known as the vegetative system. The brain is connected to the rest of the body through the sympathetic nervous system, even though the dopamine it produces cannot directly enter the blood due to the blood brain barrier. Along with the brain, dopamine receptors have been found in the kidneys, adrenalin glands and on blood vessels themselves.
Dopamine circulating in the blood serum regulates breathing and blood sugar balance. Because of this it has long been thought that brain activity and blood serum dopamine were connected. The research done by the ETH-Zurich researchers has demonstrated this connection, enabling a deeper understanding of the body’s reward system.
Fussenegger explained that eating, for example, could be used as therapeutic input due to this new module. “Using the gene network, we link up with the normal reward system,” he said. Since delicious food triggers feelings of happiness that activate the module, intervention is made in a process that usually is controlled solely by the subconscious. Because of this, daily activities could start to be used as therapeutic interventions.
For now, the dopamine hypertension model is simply a prototype. However, this work has shown that it is possible to intervene in the body’s reward system. “It works in a mouse model that simulates a human disease and the components we used to produce the module also came from humans.”
It is remains unclear whether this treatment will become available to the public, as it may take years or even decades to develop the prototype into a marketable product.
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