Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: INFLUENCES OF FIGHTING ON ENDOCRINE FUNCTION IN MAMMALS
bird species. Harding (1981) also presented several examples of this kind of interaction from her work with hamsters. She observed, for example, increases in plasma prolactin and LH levels after mating in this species. Brain (1989b) has recently reviewed the evidence that fighting and (more specifically) subjection to defeat can produce wide-ranging repercussions in the endocrine systems of rodents (see below).
HORMONE-AGGRESSION CORRELATIONS IN MAMMALS
Although we have already touched on the topic of correlations between measures of aggression and titers of hormones, there are some studies in which the relationship can be regarded as more remote than in injection-behavioral analysis studies. The data presented are remote because aggression and the particular endocrine factor are presumed (rather than measured), and there is little hope of establishing whether direct or indirect hormonal influences are involved. Such studies provide, however, useful further pointers (reviewed in Brain, 1977–1979a).
These wide-ranging investigations (reviewed in Brain, 1977–1979a) involve species differences (e.g., von Euler, 1956); domestication (Popova et al., 1980; Hammer et al., 1990); sex differences (Archer, 1976); variations in genetic constitution (Selmanoff et al., 1975); maturation (Bernard et al., 1975); body size (Barr et al., 1976); housing condition (Brain and Benton, 1983); reproductive status, including seasonal changes (Rose et al., 1978), sexual cycles (Floody and Pfaff, 1977), pregnancy (Svare, 1977) and lactation (Haug and Brain, 1989); photoperiod (Balthazart and Hendrick, 1977); diet (Schultz and Lore, 1987); endocrine dysfunction (Tonks, 1977), and behavioral stereotyping (Wehle et al., 1978). The implied associations are complex but involve many species and varied endocrine factors.
INFLUENCES OF FIGHTING ON ENDOCRINE FUNCTION IN MAMMALS
Brain (1990a) has reviewed the hormonal impact of threat and fighting in rodents. He pointed out that the stress of fighting or defeat in rats and mice can produce temporally complex changes in hypothalamic releasing factors (LHRF and thyrotropin releasing factor); anterior pituitary hormones (TSH, ACTH, LH, and FSH); thyroid hormones; adrenomedullary catecholamines (e.g., epinephrine); adrenal glucocorticoids (e.g., corticosterone); and sex steroids. In general, adrenocortical hormones are increased and sex steroids
