Based on research articles read thus far, there is a linkage between vasopressin and oxytocin and social behavior, and there is also a linkage between early life/ prenatal stress and vasopressin and oxytocin receptor densities in the brains of rodents. Stress is defined as the brain’s response to any demand and can be triggered by a multitude of factors. Not all stress is bad stress, and stress can sometimes be used as a motivator. Anxiety can be defined psychiatrically as a nervous disorder characterized by a state of excessive uneasiness and apprehension.
The difference between stress and anxiety is that stress is a response to a threat in a situation and anxiety is a reaction to the stress. It is important to note the difference so that it is clear that a stress response is measured and so that there is no confusion between the two, as the words are often used interchangeably, but they do not mean the same thing. Prenatal stress is the exposure of an expectant mother to distress which can be caused by stressful life events or environmental hardships.
Prenatal stress can cause many problems later on in adulthood, such as high blood pressure or heart disease. Oxytocin is a hormone released by the pituitary gland. Oxytocin is typically known for causing contractions during labor and the stimulation of milk into the milk ducts of the breasts. Oxytocin is also called the “cuddle hormone” or the “love hormone” because it is released when people snuggle or bond socially. Oxytocin is also sometimes studied in regards to autism, due to the fact that autistic patients do not interact socially the proper way.
With an increase of oxytocin, patients with autism may show improvement in social play. The property that becomes most important this study is that oxytocin is thought to modulate social behavior in a variety of species, including humans and rats. Vasopressin, also known as Arginine Vasopressin or AVP is also a hormone that is released by the pituitary gland. I acts to promote the retention of water by the kidneys and increase blood pressure. Vasopressin is, on some cases considered to be the antagonist to oxytocin, although that is not the properties it is being used for in this type of study.
Both vasopressin and oxytocin effect aggressive, affiliative, and sexual behavior, making them prime hormones to study in relation to social behavior. Current research is being conducted on these two hypotheses in order to determine the roles that these hormones have on social behavior and how stress affects social behavior and these two hormones. Vasopressin and oxytocin are studied in regards to social play because of their roles in behavior.
In a study done by De Souza et al. n 2013, the number of oxytocin and vasopressin neurons were altered in adult rats due to prenatal stress, as were their social behaviors. Because stress is such a wide topic, it is necessary to narrow the field. That is why this research is focused on prenatal and early life stress. As previously stated stress early on in life can lead to complications later on in life into adulthood. Diseases such as obesity and heart disease can be common, as well as high blood pressure.
Children that were prenatally stressed also are at higher risks for asthma and ADHD and other and other anxiety and depressive disorders. Stress is experienced by all people at many points in their lives. By understanding the underlying mechanisms behind stress, scientists can come up with ways to cope with it. Oxytocin and vasopressin are necessary in this study to test whether stress affects social play and interaction. When a rodent is stressed early on in life or prenatally, it is possible that the density of the vasopressin and oxytocin receptors decreases, causing hindered social abilities.
By reducing the number of receptors available to oxytocin and vasopressin, the hormones are not spreading through the body in the same volume that they should, causing social deficits. These social deficits include the ability to recognize or remember a juvenile rat from previous tests, an increased amount of fighting with newly introduced rats and low elevated plus maze scores. In an elevated plus maze test, a low score would include an increased amount of time in the closed arms and a decreased amount of time in the open arms.
Due to the rat’s inherent nature to want to be in dark, enclosed spaces, increased time in the closed arms means that the rat is stressed and uncomfortable in their environment. This behaviour demonstrates the behavioral patterns of stressed rodents. If the rodent was comfortable in the environment, it would spend more time in the open arms, which goes against rodents inherent nature. In social recognition tests, as mentioned before, rats that have been prenatally stressed, or experienced early life stress tend to behave poorly.
In cases where a juvenile rats is brought in for 4-5 cycles and then replaced with a different juvenile rat, researchers are looking for social activity, in this case, sniffing. The researchers expect that for the first trials with the same rat, the amount of sniffing would decrease over time, and with the addition of the new rat, the sniffing would be equal to the sniffing of when the original rat was brought in the first time. Researchers have concluded that stressed rodents do not perform as well on this test due to the lack of dramatic increase in sniffing behavior showing interest.
In other social tests where rodents are closed off from each other for a typical time period of 24 hours and then allowed to interact, stressed rats tend to be more aggressive, showing more violent behaviors. Due to these tests, researchers can identify the behavior patterns of stressed individuals and figure out healthy ways to reduce stress. This next step in this field would be to identify a way that stressed could be reduced early on in life or even on the womb so that oxytocin and vasopressin receptor density is not impacted and stressed individuals do not pass on their stress to their offspring.
Another step in this field of research would be to identify a hormone that is causing an increase in stress and suppress that slightly so that the individual could experience good stress, but not be overwhelmed by it. Many people are still dealing with stress disorders and there needs to be an effective solution to cope with this. Prenatally stressed people or people that experience early life stress are doomed for the rest of their lives to live under the shadow of their past. Research needs to be conducted to figure out a way to stop these illnesses before they happen.
Even though a great deal of research has been done on stress, a major topic that remains fairly untouched is how to effectively deal with stress in a healthy way. There are many methods to help reduce stress including exercise and meditation, but there is still a gap between what is causing stress and stopping stress. Many stress and depressive related illnesses still exist and it is imperative to conduct research to help people overcome their stress and lived more fulfilled healthy lives.