Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: Neuropharmacologic Modulation of GABA
was also measured in the striatum and hypothalamus of Spanish fighting bulls versus nonaggressive Friesian bulls (Muñoz-Blanco et al., 1986).
By contrast, aggressive female mice confronting a lactating intruder had higher whole-brain GABA levels (Haug et al., 1980), and more specifically, GABA was elevated in the hypothalamus, olfactory bulbs, and amygdala of very aggressive mouse strains (Haug et al., 1984). With regard to GABA receptors, small increases in GABA binding in limbic brain areas were noted in aggressive female hamsters (Potegal et al., 1982), and amygdaloid muscimol binding was increased in muricidal rats (DaVanzo et al., 1986).
The pattern of GABA concentrations and GABA receptor binding in animals with a high propensity to engage in several aggressive behaviors highlights the large changes in opposite direction in discrete brain regions. The present neurochemical evidence does not warrant a generalization that attributes to GABA an inhibitory influence on aggressive behavior in animals and violent behavior in humans.
Neuropharmacologic Modulation of GABA
As detailed in Table 4, section B, activation of GABA-A receptors with systematic muscimol decreases the percentage of rats that kill (Delini-Stula and Vassout, 1978; Mandel et al., 1979; Molina et al., 1986), but facilitates muricide and irritability when given into the septum (Potegal et al., 1983). Activation of GABAA and B receptors suppressed pain-induced defensive responses in rats (Rodgers and Depaulis, 1982), aggressive responses in mice (Puglisi-Allegra and Mandel, 1980), and muricidal behavior in rats (Delini-Stula and Vassout, 1978). Under conditions in which normally no aggressive behavior is likely, the GABA agonist THIP (4,5,6,7-tetrahydroisoxazolo[5,4,-c]pyridin-3-01 HC1) may induce aggressive behavior in rats, whereas the antagonist bicuculline suppresses aggressive and facilitates defensive responses in rats (Depaulis and Vernes, 1985). The receptor agonist, THIP, may enhance or suppress the killing response. Intracerebral blockade of GABAA receptors with bicuculline suppressed muricide (Depaulis and Vernes, 1983, 1984; Molina et al., 1986), and when this receptor antagonist was injected into the hypothalamus and amygdala, it reduced maternal aggression in rats (Hansen and Ferreira, 1986). In nonkiller rats, the GABA antagonists bicuculline and picrotoxin may induce the muricidal response (Mandel et al., 1979).
