Effects of seasons and light therapy on G protein levels in mononuclear leukocytes of patients with seasonal affective disorder

Sofia Avissar, Gabriel Schreiber, Yakov Nechamkin, Isaac Neuhaus, Gregory K. Lam, Paul Schwartz, Erick Turner, Jeffery Matthews, Susana Naim, Norman E. Rosenthal

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Background: Information-transducing heterotrimeric G proteins have been implicated previously in the mechanism of action of mood stabilizers and in the pathophysiology of mood disorders, Mononuclear leukocytes of patients with unipolar and bipolar depression have been characterized by reduced measures of the stimulatory and inhibitory G proteins. In this study, patients with seasonal affective disorder (SAD) were measured for mononuclear leukocyte G protein levels while depressed during the winter, following light therapy, and in remission during the summer. Methods: Twenty-six patients with SAD and 28 healthy subjects were assessed in the study. The immunoreactivities of G5α, G1α, and Gβ subunit proteins were determined by Western blot analysis of mononuclear leukocyte membranes with selective polyclonal antibodies for the various G subunit proteins, followed by densitometric quantitation using an image analysis system. Results: Untreated patients with SAD and winter, atypical-type depression showed significantly reduced mononuclear leukocyte immunoreactive levels of G(s)α and G(i)α proteins, similar to previous observations in patients with nonseasonal major depression. The reduced G protein levels were normalized with 2 weeks of light therapy. The same patients while in remission during the summer had G protein levels that were similar to those of healthy subjects. Conclusions: G protein-immunoreactive measures in patients with SAD are suggested as a state marker for winter depression, which is normalized by light treatment and during the summer. We speculate that light may exert its effects via normalization of transducing (G1 protein) levels, which are thought to be reduced in winter depression.

Original languageEnglish (US)
Pages (from-to)178-183
Number of pages6
JournalArchives of General Psychiatry
Issue number2
StatePublished - Feb 1999
Externally publishedYes

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Psychiatry and Mental health


Dive into the research topics of 'Effects of seasons and light therapy on G protein levels in mononuclear leukocytes of patients with seasonal affective disorder'. Together they form a unique fingerprint.

Cite this