Oxytocin is a neurohypophysial polypeptide made up of nine peptides in its sequence. The peptide is popularly known as OXT because of the gene which codes it. The primary function of the peptide is to act as a neuromodulator and it uses neurotransmitters to elicit its functionality. The peptide has a molecular mass of 1007.19 and structural formula of C43H66N12O12S2.
How it Works
According to a recent scientific study carried out on animal subjects, it has been determined that oxytocin is produced in the hypothalamus, an area that links the neuroendocrine and nervous system. In addition, the peptide can be secreted and stored in the posterior pituitary gland found at the bottom of the hypothalamus at the base of the human brain.
The gland is important in controlling numerous functions such as pain, sexual organs, metabolism and thermoregulation among others. The peptide is released as a non-active precursor via the up-regulation of the OXT gene, a protein which includes neurophysin I and has been known to be an oxytocin carrier. When the hormone is hydrolyzed and converted into tiny pieces via a series of enzymes, the last process of hydrolysis is carried out by a monooxygenase enzyme.
It is imperative to note that the oxytocin peptide is formed in the magnocellular neurosecretory cells of the paraventricular and supraoptic nuclei. After generation of the peptide, it is stored in herring bodies in the posterior pituitary axon terminals and is carried to the specific organ of action via blood. Since the peptide interacts with the basal forebrain, it is responsible for regulating behaviors such as aggression, fear and reinforcement, among others.
Oxytocin behaviors are expressed by different neurons in the brain including the septum, amygdala, ventromedial hypothalamus and brainstem. Scientific research on the peptide showed that oxytocin is packaged in dense core vesicles and is often fixed to the neurophysin I. Secretion of the hormone is often controlled by electrical pulses of oxytocin cells in the hypothalamus. These cells are essential in creating an action potential that spreads the axons in the pituitary gland nerve endings.
Oxytocin exists in different tissues of the organisms. These tissues may include placenta, retina, pancreas, adrenal medulla and corpus luteal. Research findings showed that the peptide is expressed in the pituitary gland and cannot enter the brain when it is expressed. One behavior associated with the presence of the oxytocin hormone is the process of sexual arousal. Studies revealed that when the hormone is injected into mice, they showed spontaneous erections and increased sexual behavior. In addition, the peptide has shown to increase maternal bonding and trust among partners.
In addition, the peptide increases maternal instincts and initiates mother-to-child bond. The milk let down is initiated when the mother smells the baby or when she hears the baby crying. More studies are being conducted on the peptides ability to induce emotional and arousal responses. In another context, a different peptide is used to induce labor. It is imperative to note that all peptides are for research purposes only.
Oxytocin and Brain Function
A scientific research study based on mice showed that oxytocin is expressed in the pituitary gland and it does not re-enter the brain once it is expressed. It is therefore thought that behavioral characters are associated with the presence of the oxytocin peptide emanating from the release to oxytocin neurons and pituitary gland is activated fully. One feature associated with oxytocin is sexual behaviors.
Studies showed that when the peptide is injected into the cerebrospinal fluid of male rats, they experienced spontaneous erections and also caused lordosis behaviors in female rats which direct to increase in sexual perception. One other behavior with the presence of oxytocin in the system is bonding or attachment. Once the peptide is administered, studies revealed that it increased male-to-female bonding and attachment. This feature is essential especially in lactating mothers or lactating mice in the study.
Moreover, studies showed that administration of oxytocin in lactating mice, in essence, the peptide contributes to letdown reflexes. This is an essential feature which regulates the presence of milk in animals that breastfeed. The action is often stimulated by the suckling process of young ones and when information is passed to the signal nerves, it triggers a signaling cascade which fires a potential intermittent burst essential for regulation.
Some studies have linked the presence of the oxytocin peptide to contraction of the uterine wall. This is essential especially in animals after giving birth. Since the hormone is endogenous, it will prompt smooth muscle relaxation and expulsion of the mature baby. Further studies showed that the presence of the peptide may induce contraction in pregnant mice especially in the third stage of labor. Moreover, it aids uterus clotting and placental attachment postpartum.
Oxytocin and Inflammation
Research showed that the presence of peptide oxytocin is essential in modulating inflammation. This is a complex biological response in reaction to an external harmful stimuli. The peptide accentuates multiplication and healing of cells in the peripheral and proximal organs.
In addition, oxytocin increases cytokines. This has led to the notion that oxytocin increases or accelerates wound healing process. The presence of the oxytocin peptide accentuates movement of healing components to the site of injury and this will reduce the effects of the injury and its spread.
Potential Side Effects
While the peptide is endogenously produced and in some cases administered externally, it could cause some side effects. Side effects include increased heart pressure as per mice in the studies, cardiac arrhythmia, premature ventricular contraction and nausea, impaired uterine flow, among others. Since it is an endogenous hormone, the peptide has shown to have fewer side effects which could hamper the activity and functionality of natural hormones as well as functioning of the system.