Effects of chronic desipramine administration on the locus coeruleus neuronal activity in the learned helplessness paradigm.

One week after inescapable shock (IS) exposure, animals showed an increased number of escape failures in the shuttlebox and a decreased noradrenergic (NA) transmission. The latter was assessed by electric activity of locus coeruleus (LC) neurons. Seven daily injections of desipramine (DMI) were effective in reducing the number of escapes failures in the shuttlebox, but such treatment did not modify the decreased electric activity of LC NA neurons observed 7 days after IS. These results are discussed in terms of the action of DMI on NA terminals in reversing the behavioral deficit induced by IS.