Vasopressin is a peptide hormone with antidiuretic and vasoactive action. Vasopressin has direct action on vasal smooth muscles and kidney collective tubules. Vasopressin also plays a role in the central nervous system and influences smooth muscles of the gastrointestinal tract.

Brain Res. Jan 29 2014. Oxytocin And Vasopressin Modulation Of The Neural Correlates Of Motivation And Emotion: Results From Functional MRI Studies In Awake Rats. Oxytocin and vasopressin modulate a range of species typical behavioral functions that include social recognition, maternal-infant attachment, and modulation of memory, offensive aggression, defensive fear reactions, and reward seeking. We have employed novel functional magnetic resonance mapping techniques in awake rats to explore the roles of these neuropeptides in the maternal and non-maternal brain. Results from the functional neuroimaging studies that are summarized here have directly and indirectly confirmed and supported previous findings. Oxytocin is released within the lactating rat brain during suckling stimulation and activates specific subcortical networks in the maternal brain. Both vasopressin and oxytocin modulate brain regions involved unconditioned fear, processing of social stimuli and the expression of agonistic behaviors. Across studies there are relatively consistent brain networks associated with internal motivational drives and emotional states that are modulated by oxytocin and vasopressin.

Vascular effects of Vasopressin
Vasopressin is a nonapeptide synthesized in the hypothalamus and released upon stimulations such as hyperosmolality, hypotension and hypovolaemia. In acute shock states serum vasopressin levels increase rapidly and decrease in prolonged septic shock. The administration of vasopressin in healthy subjects has little effect, whereas in vasodilatory shock it increases the mean arterial pressure through V1 receptors and decreases the cardiac output. Vasopressin stimulates the V2 receptors in the kidney leading to reabsorption of water.

Vasopressin and Steroid rage
Anabolic steroid users may behave aggressively for a long time after stopping the drug, but the behavior -- and some of the brain changes linked to it -- may be reversible. In an experiment with teenage hamsters given anabolic steroids, scientists found that the animals continued to chase and bite their brethren for days during withdrawal from the muscle-building hormones. At the same time, activity in the brain's vasopressin system, which is linked to aggression, was elevated in the steroid-treated hamsters. After a couple weeks, however, both vasopressin activity and aggression subsided. The hamsters went back to normal by day 19 of steroid withdrawal. In human teenagers, that could translate to many weeks or months, or perhaps years? Although the hamsters' vasopressin systems also went back to normal, it's possible that other brain systems affected by steroids may not recover that quickly. Steroid abuse may hinder the development of the serotonin system, which suppresses aggression. So at a time when the young brain is still taking shape, teenage steroid users may enhance the development of the brain's aggression center while suppressing the maturation of its calming center. Could the damage be permanent? More research will provide the answer. Source: Behavioral Neuroscience, February 2006.

Arginine Vasopressin (AVP)
Arginine vasopressin, also known as antidiuretic hormone, is a hormone predominantly released when the body is low in water. Arginine vasopressin causes the kidneys to conserve water by concentrating the urine and reducing urine volume. Arginine vasopressin is sometimes used in a hospital setting to deal with situations of low blood volume. Arginine vasopressin has been sometimes used successfully during cardiopulmonary resuscitation CPR.