Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: Dopaminergic Correlates of Animal Aggression
from less aggressive ones in terms of their NE turnover (Karczmar et al., 1973; Goldberg et al., 1973) or turnover is increased in the more aggressive strains (Bernard, 1975). When rats are reacting defensively to electric shock, their diencephalic and mesencephalic NE turnover is increased (Stolk et al., 1974). Cats as well as rats that rage after acute brain stem transection or after septal lesions show elevated hindbrain NE turnover (Reis and Fuxe, 1964, 1968; Salama and Goldberg, 1973b), but "rage" due to amygdaloid stimulation lowers NE levels in their brain stem (Reis and Gunne, 1965). Hypothalamic and amygdaloid levels of the NE metabolite MHPG (3-methoxy-4-hydroxyphenylglycol) were also reduced in rats that engaged in stress-induced biting (Tsuda et al., 1988). When rats have just killed a mouse, their forebrain NE turnover is increased (Goldberg and Salama, 1969; Salama and Goldberg, 1973b; Tani et al., 1987).
Anatomically more discrete measurements of noradrenergic activity in aggressive animals often reveal opposite changes in different brain regions. Increased synaptosomal uptake of cortical NE was measured in mice after intense fighting (Hendley et al., 1973; Hadfield and Weber, 1975). Isolated mice of particularly aggressive strains show increased turnover of NE in three brain areas (frontal cortex, caudate, hypothalamus; Tizabi et al., 1979). After exhibiting fighting behavior they have less NE in olfactory tubercle and substantia nigra, but increased NE in the septal forebrain (Tizabi et al., 1980). Increased levels of NE were also found in the hypothalamus of rats that kill mice (Tani et al., 1987). However, many investigations fail to detect any changes in NE levels, turnover, or synthesis in brain regions of animals exhibiting aggressive behavior (e.g., Payne et al., 1984, 1985).
Brain norepinephrine undergoes large changes before, during, and after different kinds of aggressive and defensive behavior in animals; these changes are, however, localized in specific brain regions that even within the limbic system appear to exert opposing behavioral effects. At present, it is not yet possible on the basis of experimental evidence from animal models to map a "noradrenergic neurochemical profile" of different brain regions that are critically important just preceding or consequent to an aggressive act.
Dopaminergic Correlates of Animal Aggression
As detailed in Table 2, section B, levels of DA and measures of DA synthesis and turnover in the whole brain have been found
