New York, Nov 1 (IANS): The brain regulates social behaviour differently in males and females and certain drugs for psychiatric disorders may have opposite effects on the two sexes, says a study.

The researchers discovered that the neurotransmitter serotonin (5-HT) and the hormone arginine-vasopressin (AVP) act in opposite ways in males and females to influence aggression and dominance.

Because dominance and aggressiveness have been linked to stress resistance, these findings may influence the development of more effective gender-specific treatment strategies for stress-related neuropsychiatric disorders.

"These results begin to provide a neurochemical basis for understanding how the social brain works quite differently in males and females," said lead researcher Elliott Albers, Professor at Georgia State University in the US.

Prominent sex differences occur in the incidence, development and clinical course of many neuropsychiatric disorders.

Women, for example, have higher rates of depression and anxiety disorders such as posttraumatic stress disorder (PTSD), while men more frequently suffer from autism and attention deficit disorder.

Despite profound sex differences in the expression of social behaviour and the incidence of these psychiatric disorders, little is known about how the brain mechanisms underlying these phenomena differ in females and males.

Further, limited knowledge exists regarding sex differences in the efficacy of treatments for these disorders.

As a result, current treatment strategies are largely the same for both sexes.

In this study conducted in hamsters, the researchers found that serotonin (5-HT) and the arginine-vasopressin act in opposite ways within the hypothalamus to regulate dominance and aggression in females and males.

This study also found that administration of a commonly prescribed drugs for psychiatric disorders, increased aggression in females and inhibited aggression in males.