Delayed vasodilatory response to methylnicotinate in patients with unipolar depressive disorder

Recent evidence has suggested an important role for lipids in the etiology and treatment of depression. Methylnicotinate-induced vasodilation can be used to investigate lipid-dependent signalling mechanisms involving the phospholipase A2 (PLA2)/cyclooxygenase pathway, an important signalling system involved in the action of several neurotransmitters including serotonin. To investigate whether abnormalities in this signalling system may occur in depressive illness, we undertook a study of methylnicotinate response in unipolar depression (UD).

Methylnicotinate was applied to the forearm of 20 patients with depression and 38 age and sex-matched healthy volunteers (HV). The resulting erythema was assessed over a 15-min period.

Methylnicotinate-induced erythema was reduced in subjects with depression compared to HV at 5 min after application, it returned to normal after 15 min. Thus, although the maximal response to methylnicotinate appears normal, patients with UD exhibit an apparently delayed response.

The major limitation is that all unipolar patients were medicated at the time of testing.

Our results support the hypothesis that UD may be associated with abnormalities in lipid-associated signalling systems, and may provide insight into how lipid intake may modulate depressive symptoms.