What is Neuropeptide Y?

In 1982, researchers were able to isolate neuropeptide Y (NPY) from the porcine hypothalamus gland. There were many processes of the brain that were associated with the neuropeptide Y. But what is neuropeptide Y and its importance in physiology? Let's understand the role it plays in our body processes.

Neuropeptide Y is a chain of peptide chemical messengers that are secreted from the hypothalamus. It is basically a 36 amino acid peptide chain that functions as a neurotransmitter in the brain. It also has a role in the autonomic nervous system. NPY is one of the highly conserved neuroendocrine peptides through evolution. NPY has a tertiary structure.

There are many functions of neuropeptide Y in the physiological functions of the brain. NPY is secreted from the hypothalamus. It helps in regulating memory, energy homeostasis, and epilepsy. There are six neuropeptide Y receptors that interact and lead to physiological effects.

Regulation of the sympathetic nervous system is carried out by NPY that helps in controlling blood pressure. It also acts as a stabilizer in regulation of anxiety and arousal. Its main effect is to increase the intake of food and decrease physical activity. It also plays a role in peripheral vascular resistance, as well as contractility of the heart.

Like all neurotransmitters, neuropeptide Y too has its set of receptors. There are many peripheral and central targets for neuropeptide Y. These receptors are heterogeneous in nature, and include Y1, Y2, Y4, and Y5 receptors. They are G protein-coupled receptors in the rhodopsin-like GPCR family.

These receptors can carry out metabolic changes in the target cells. They are able to do so by changing the opening ion channels. This process makes the receptors metabotrophic. The Y1 and Y5 proteins stimulate hunger, whereas, appetite inhibition is carried out by Y2 and Y4. 

When there is increase in NPY hormones and Y1 receptors, it blocks the production of substance P. This substance P carries the signal of pain to the central nervous system. Thus, NPY and Y1 receptors help in decreasing the pain awareness, and stimulates gradual pain tolerance.

Researchers have found a connection between neuropeptide Y and body weight. It has been found the Y1 and Y5 receptors stimulate food intake. NPY is released during emotional stress. It has a calming effect, but induces one's desire to eat. Also, it leads to decrease in the metabolism of fats, thus, increasing the chances of obesity.

Researchers have also found that NPY is stimulated by a high fat and high sugar diet, in mice and monkeys. This causes build up of fat in the abdominal region.

If the levels of this hormone are altered, it could help in decreasing fat in undesired body areas, and in turn, help it to accumulate in regions where they are needed the most. Thus, NPY can be useful in decreasing weight, and maintaining normal body weight.

As you can see, neuropeptide Y plays a major role in the processes of the brain. There are many receptors as well as hormones accumulated in various areas of the brain. Weight gain as well as weight loss, pain tolerance, decrease in physical activity, etc., are some of the roles of NPY.