Background: 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).
Methods: 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.
Results: 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.
Limitations: The major limitation is that all unipolar patients were medicated at the time of testing.
Conclusions: 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.