Presence of oxytocin, vasopressin and atrial natriuretic peptide and their modification in rat hypothalamic paraventricular nucleus during resistance training

Regular Aerobic Voluntary Exercise Increased Oxytocin in Female Mice: The Cause of Decreased Anxiety and Increased Empathy-Like Behaviors

Background:

It is known that regular physical activity reduces anxiety. Low anxiety levels affect mood, emotions, and empathy. Oxytocin is a powerful hormone that regulates social interaction, sexual reproduction, maternal–infant bonding, milk release, empathy, and anxiety. Empathy is an important behavior in the living community; and also important for sportsmen during sportive competition and daily living life, because sportsmen are also role model of people.

Aims:

To investigate the effects of voluntary physical activity on oxytocin, anxiety, and empathy levels as well as the relationship between them.

Study Design:

Animal experiment.

Methods:

Male and female mice were made to exercise in running wheel cages for 6 weeks. Their empathy and anxiety levels were evaluated by using Helping Behavior test and elevated plus maze and open field test, respectively. And then the brain and blood oxytocin levels were measured.

Results:

Empathy-like behavior was improved in both genders of the exercise groups (door-opening time decreased in both genders of exercise groups, p for both=0.0001). As a response to exercise, both the brain and serum oxytocin levels increased in female mice (both of p=0.0001); however, in males, oxytocin levels increased in only the brain (p<0.05). Anxiety levels decreased in all the exercise groups (increased time spent in the middle area of open field test, both genders, p=0.002; increased time spent in the open arms of elevated plus maze test, females p=0.004, males p=0.0001). There was a strong negative correlation between serum oxytocin levels and door opening time of helping behavior equipment, and moderate negative correlation was found between the brain oxytocin levels and door-opening time of helping behavior equipment in females. However, there was no correlation between both the brain and serum oxytocin levels and empathy behavior in males. But there were very strong positive correlations between low anxiety indicators and both the brain and serum oxytocin levels in both the genders.

Conclusion:

Voluntary physical activity decreases anxiety and increases empathy-like behavior in mice; which is associated with increased oxytocin levels in female mice but not in male mice. Further research is required to investigate the mechanisms of exercise effect on anxiety and empathic brain pathways in males.

Why is running a marathon like giving birth? The possible role of oxytocin in the underestimation of the memory of pain induced by labor and intense exercise

Pain can be overestimated, underestimated or reported accurately at recall. The way pain is remembered seems to depend on certain factors, including the type of pain or, in other words, its cause, the context, and the meaning it has for the person suffering from it. For instance, episodes of chronic pain, as well as pain related to surgery, are often overestimated at recall. Interestingly, research shows that pain induced by parturition or marathon running is often underestimated at recall despite the fact that both are not only physically grueling but also emotionally intense experiences. However, both processes can likewise be considered positive events, as opposed to most that involve pain. On the neurophysiological level, one of the similarities between giving birth and running a marathon is the particular involvement of the oxytocin system. Oxytocin is involved both in parturition and intense exercise, for various reasons. During labor, oxytocin mediates uterine contractions, while in the case of extensive running it might be involved in the maintenance of fluid balance. It also has well-documented analgesic properties and plays an important role in memory formation and recall. It has been suggested that oxytocin modulates the output of the central nucleus of the amygdala (CeA) during the fear recall. Moreover, it has been demonstrated that oxytocin can impair fear learning and influence the memory of both positive and negative emotionally salient stimuli. We propose that the reason for pain to be remembered in a more favorable light is the central action of oxytocin in the central nucleus of the amygdala, first and foremost during the encoding phase.

Animal models of resistance exercise and their application to neuroscience research

BACKGROUND

Numerous studies have demonstrated that participation in regular resistance exercise (e.g., strength training) is associated with improvements in mental health, memory, and cognition. However, less is known about the neurobiological mechanisms mediating these effects. The goal of this mini-review is to describe and evaluate the available animal models of resistance exercise that may prove useful for examining CNS activity.

NEW METHOD

Various models have been developed to examine resistance exercise in laboratory animals.

COMPARISON WITH EXISTING METHODS

Resistance exercise models vary in how the resistance manipulation is applied, either through direct stimulation of the muscle (e.g., in situ models) or through behavior maintained by operant contingencies (e.g., whole organism models). Each model presents distinct advantages and disadvantages for examining central nervous system (CNS) activity, and consideration of these attributes is essential for the future investigation of underlying neurobiological substrates.

RESULTS

Potential neurobiological mechanisms mediating the effects of resistance exercise on pain, anxiety, memory, and drug use have been efficiently and effectively investigated using resistance exercise models that minimize stress and maximize the relative contribution of resistance over aerobic factors.

CONCLUSIONS

Whole organism resistance exercise models that (1) limit the use of potentially stressful stimuli and (2) minimize the contribution of aerobic factors will be critical for examining resistance exercise and CNS function.

Atrial natriuretic peptide (ANP) and oxytocin-expression in the adult rat and mouse cerebellum

Background

Many studies are in the literature on the ANP and oxytocin-presence in the brain, but very few studies with controversial results are reported on the presence of these peptides in the cerebellum. This immunohistochemical study investigates on the ANP and oxytocin-presence in the cerebellum of the adult rat and mouse rodents.

Results

This study, firstly, evidences the ANP- immunopositivity in cerebellar cortex of both rat and mouse rodents. In rat the molecular layer presents some few immunopositive fibers, but no neuron resulted immunopositive; the granular and Purkinje cells are immunopositive. In mouse the cerebellar cortex ANP-immunopositivity is present in all layers. The oxytocin-presence in the rat the afferent fibers are immunopositive are in the granular layer; in mouse the OT-immunopositivity is in the molecular layer only.

Conclusions

This study, firstly, shows that ANP and OT are present in the cerebellar cortex both in rat and mouse rodents. In the mouse cerebellar cortex ANP-presence is more diffuse and OT- localization differences in the two species.