cortex as well as in other cortical brain regions. 5-HT2A receptor binding in suicide victims may be linked to more violent methods of suicide since the studies reporting increases (Arango et al., 1990; Arora and Meltzer, 1989; Hrdina et al., 1993; Laruelle et al., 1993; Mann et al., 1986; Stanley and Mann, 1983) had greater representation of violent deaths than the others (Arranz et al., 1994; Cheetham et al., 1988; Crow et al., 1984; GrossIsseroff et al., 1990a; Lowther et al., 1994; Owen et al., 1983; 1986).

Several other factors may influence the outcomes of these analyses. Psychotropic medication may down-regulate 5-HT2A receptors (Yates et al., 1990), and potentially obscure or reverse the up-regulation related to suicide. The presence or absence of a depressive illness may also be relevant (Yates et al., 1990); high 5-HT2A receptor number may be associated with the presence of a depressive illness independent of suicide risk.

Serotonin Receptors: 5HT1A

Another major cortical postsynaptic serotonin receptor is the 5-HT1A receptor. Two studies reported an increase in 5-HT1A binding in suicide victims (Arango et al., 1995; Joyce et al., 1993) and four did not (Brodsky et al., 1997; Dillon et al., 1991; Matsubara et al., 1991; Stockmeier et al., 1997). Arango et al. (1995) and Joyce et al. (1993) found the increase in 5-HT1A binding to be confined to discrete brain regions. Corticosteroids can mediate stress effects via mineralocorticoid (MR) and glucocorticoid (GR) receptors on hippocampal 5-HT1A receptors (Lopez et al., 1998). Stress elevates glucocorticoid levels and downregulates hippocampal 5-HT1A receptors in rodents. Suicide victims have low levels of MR and 5-HT1A mRNA in the hippocampus, an effect consistent with stress (Lopez et al., 1998).

Serotonin Receptors: Others

Few studies are published of 5-HT1B, 5-HT2C, and 5-HT1D receptors in suicide victims (Arranz et al., 1994). Lowther et al. (1997) reported an increase in 5-HT1D binding in globus pallidus, but not in putamen, parietal or prefrontal cortex of violent suicide victims. Huang et al. (1999) did not find any alteration in 5-HT1B binding in prefrontal cortex. More work needs to be done mapping these receptor changes.

The Noradrenergic System

Altered brain noradrenergic transmission also appears to be associated with suicidal behavior. Postmortem studies performed to date have sought to examine the noradrenergic system in brain by: measuring the

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