From inflammation to depression – St Johns wort as a therapeutic approach

An increasing number of clinical and preclinical data shows that inflammatory processes may be involved in the etiology of depression [1, 2]. At least in some depressed patients inflammation markers are enhanced. An IFN-α-induced rise of TNF-α and IL-6 may induce depressive symptoms [3]. Psychic stress is not only a trigger of depressive symptoms, but also of a lower antioxidative capacity, similar to that in inflammatory diseases.

As many herbal extracts have anti-inflammatory actions, the question is, whether these are also involved into the antidepressive action of St Johns wort [4]. It was addressed by a systematic data base search.

St Johns wort extracts and their components have anti-inflammatory and anti-oxidative actions in vitro [5,6], in vivo [2,7] and, in dermatology, also clinically [8]. In a model of a stress induced depression, St Johns wort also normalized the lowered antioxidative capacity [2] and influenced gene expression of pro-inflammatory cytokines [7].

As St Johns wort extracts have anti-inflammatory properties, it is plausible that these are involved also in the therapeutic use in depression, and have possibly been underestimated up to now.

References:

[1] Dantzer R et al. 2008, Nature Reviews Neuroscience 9, 46

[2] Grundmann O et al. 2010, Neuropharmacology 58, 767

[3] Raison CL and Miller AH, 2011, Curr Psychiatry Rep 13, 467

[4] HMPC 2009, EMA/HMPC/101304/2008

[5] Birt DF et al. 2009, Pharm Biol 47, 774

[6] Kraus B et al. 2010, Planta Med. 76, 1340

[7] Jungke et al. 2011, Psychopharmacology 213, 757

[8] Schempp CM et al. 2002, Hautarzt 53, 93