This paper describes a hypothesis that attempts to account for how changes in noradrenergic systems in the brain can affect depression-related behaviors and symptoms. It is hypothesized that increased activity of the locus coeruleus (LC) neurons, the principal norepinephrine (NE)-containing cells in the brain, causes release of galanin (GAL) in the ventral tegmentum (VTA) from LC axon terminals in which GAL is colocalized with NE. It is proposed that GAL release in VTA inhibits the activity of dopaminergic cell bodies in this region whose axons project to forebrain, thereby resulting in two of the principal symptoms seen in depression, decreased motor activation and decreased appreciation of pleasurable stimuli (anhedonia). The genesis of this hypothesis, which derives from studies using an animal model of depression, is described as well as recent data consistent with the hypothesis. The formulation proposed suggests that GAL antagonists may be of therapeutic benefit in the treatment of depression.

The data reveal potentially important and apparently additive effects of Dbh genotype and disulfiram administration on PFC catecholamine metabolism. These effects may have implications for genetic control of DBH activity in humans and for understanding therapeutic effects of disulfiram.

No abstract

Although interleukin-1 (IL-1) has been implicated in an array of brain functions, past studies usually have failed to detect IL-1 bioactivity in the brain of normal healthy animals. However, in view of the potency of IL-1 in brain, small amounts of this cytokine may normally act in brain, and such quantities can escape detection by assay methods usually employed. Although bioassays are highly sensitive for detecting IL-1, these can be compromised by molecules in brain tissue other than IL-1, and attempts to purify IL-1 from brain tissue can result in significant loss of IL-1 from samples. In this study, we have refined our method of assessing brain IL-1 bioactivity by first semi-isolating IL-1 with a Sephadex minicolumn and then measuring IL-1 activity with a sensitive D10 cell assay. To confirm that our assay was specific for IL-1, a monoclonal antibody against IL-1 receptor was used to block any observed IL-1 activity. We report here that IL-1 bioactivity can be reliably detected in both the cell-free supernatant and cell lysate of brainstem, cortex, diencephalon, and hippocampus of normal rat brain. These results lend support to some recent studies that found IL-1 may play important roles in the functions of normal brain.

The findings suggest that DA function differs in lines of rats selectively bred for differences in swim behavior, a feature that may make these lines useful for studying certain depressive symptoms that might be related to DA function.