“…Also, it is well known that peripherally secreted hormones, including androgens, glucocorticoids and growth hormone and centrally secreted opioids influence the development and the degree of physiological and pathological aggressiveness in experimental animals (Grieng et al, 2001) and in humans (Olweus et al, 1988;Coccaro et al, 1997;Gerra et al, 1996Gerra et al, , 1997Gerra et al, , 1998Finkelstein et al, 1997;Archer et al, 1998;Aromaki et al, 1999;Van Herringen et al, 2000;Pope et al, 2000;Grieng et al, 2001;Thiblin and Parlklo, 2002;O'Connor et al, 2002;Eriksson et al, 2003;Rowe et al, 2004). Little is known about the influence that female sexual hormones exert on this behavioral parameter, even though in experimental animals of both sexes, especially in major primates, aggressive behavior has been linked to variations of prenatal and postnatal estrogen secretions (Simon and Whalen, 1986;Finkelstein et al, 1997;Girolami et al, 1997;Palanza et al, 1999;Toda et al, 2001).…”