scholarly journals The darkness and the light: diurnal rodent models for seasonal affective disorder

2021 ◽  
Vol 14 (1) ◽  
pp. dmm047217
Author(s):  
Anusha Shankar ◽  
Cory T. Williams

ABSTRACTThe development of animal models is a critical step for exploring the underlying pathophysiological mechanisms of major affective disorders and for evaluating potential therapeutic approaches. Although most neuropsychiatric research is performed on nocturnal rodents, differences in how diurnal and nocturnal animals respond to changing photoperiods, combined with a possible link between circadian rhythm disruption and affective disorders, has led to a call for the development of diurnal animal models. The need for diurnal models is most clear for seasonal affective disorder (SAD), a widespread recurrent depressive disorder that is linked to exposure to short photoperiods. Here, we briefly review what is known regarding the etiology of SAD and then examine progress in developing appropriate diurnal rodent models. Although circadian disruption is often invoked as a key contributor to SAD, a mechanistic understanding of how misalignment between endogenous circadian physiology and daily environmental rhythms affects mood is lacking. Diurnal rodents show promise as models of SAD, as changes in affective-like behaviors are induced in response to short photoperiods or dim-light conditions, and symptoms can be ameliorated by brief exposure to intervals of bright light coincident with activity onset. One exciting avenue of research involves the orexinergic system, which regulates functions that are disturbed in SAD, including sleep cycles, the reward system, feeding behavior, monoaminergic neurotransmission and hippocampal neurogenesis. However, although diurnal models make intuitive sense for the study of SAD and are more likely to mimic circadian disruption, their utility is currently hampered by a lack of genomic resources needed for the molecular interrogation of potential mechanisms.

1995 ◽  
Vol 7 (3) ◽  
pp. 75-79
Author(s):  
J. Beullens

SummaryMelatonin is a hormone secreted by the pineal gland mainly during the night. The discovery that this melatonin secretion decreases under the influence of bright light, gave rise to the use of light therapy in some affective disorders. The literature on the relationship between melatonin secretion and mood is reviewed concerning seasonal affective disorder, non-seasonal affective disorder and premenstrual syndrome. Light therapy could reduce an abnormal high melatonin secretion back to normal proportions. None of the affective disorders, however, is accompanied by an unusual high melatonin level. Nevertheless, light therapy as well as other therapies that suppress melatonin have a therapeutic effect. This is not the case with the administration of melatonin. Mood is not affected by extra melatonin in seasonal affective disorder but it is in both other affective disorders. Melatonin plays a part in the pathogenesis of the affective disorders but it is not yet clear which one.


2015 ◽  
Vol 118 ◽  
pp. 25-33 ◽  
Author(s):  
Misato Kawai ◽  
Ryosei Goda ◽  
Tsuyoshi Otsuka ◽  
Ayaka Iwamoto ◽  
Nobuo Uotsu ◽  
...  

1997 ◽  
Vol 9 (2) ◽  
pp. 71-76 ◽  
Author(s):  
R.H. Van Den Hoofdakker ◽  
M.C.M. Gordijn

The present explosive growth of interest in the therapeutic possibilities of exposure to light was triggered by a patient, Herbert Kern. He suffered from episodic depressive and manic complaints and discovered, by registering these over the years, a seasonal pattern in their occurrence. Discussions with scientists of the NIMH resulted in his participation in a bright light-treatment experiment when he was depressed in the winter of 1980-1981. He recovered.Next, the same group of investigators defined the criteria for a new syndrome, Seasonal Affective Disorder (SAD): a history of major affective disorder (according to the Research Diagnostic Criteria), at least two consecutive years in which the depressions have occurred during fall or winter and remitted in the following spring or summer, and the absence of any clear-cut seasonally changing psychosocial variable, such as work, stress and so on.


1985 ◽  
Vol 147 (4) ◽  
pp. 424-428 ◽  
Author(s):  
Steven P. James ◽  
Thomas A. Wehr ◽  
David A. Sack ◽  
Barbara L. Parry ◽  
Norman E. Rosenthal

A cross-over comparison study of exposure, in the evenings only, to bright versus dim light was carried out on nine female patients with seasonal affective disorder. A significant antidepressant effect of the bright lights was shown. No consistent observable effects were produced by the dim lights. These results support earlier studies demonstrating the efficacy of bright light given morning and evening. The antidepressant effect of light is not mediated by sleep deprivation, and the early morning hours are not crucial for a response.


CNS Spectrums ◽  
2005 ◽  
Vol 10 (8) ◽  
pp. 625-634 ◽  
Author(s):  
Andres Magnusson ◽  
Timo Partonen

AbstractThe operational criteria for seasonal affective disorder (SAD) have undergone several changes since first proposed in 1984. SAD is currently included as a specifier of either bipolar or recurrent major depressive disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The International Classification of Diseases, Tenth Edition has provisional diagnostic criteria for SAD. The most characteristic quality of SAD is that the symptoms usually present during winter and remit in the spring. Furthermore, the symptoms tend to remit when the patients are exposed to daylight or bright light therapy. The cognitive and emotional symptoms are as in other types of depression but the vegetative symptoms are the reverse of classic depressive vegetative symptoms, namely increased sleep and increased appetite. SAD is a common condition, but the exact prevalence rates vary between different studies and countries and is consistently found to be more common in women and in youth. SAD probably possibly occurs in children although not as commonly as in young adults. Some studies have found that certain ethnic groups who live at high northern latitudes may have adapted to the long arctic winter.


2003 ◽  
Vol 13 ◽  
pp. S247-S248
Author(s):  
E. Pjrek ◽  
D. Winkler ◽  
A. Konstantinidis ◽  
N. Thierry ◽  
A. Heiden ◽  
...  

1992 ◽  
Vol 32 (5) ◽  
pp. 387-398 ◽  
Author(s):  
Eliseo O. Salinas ◽  
Claude M. Hakim-Kreis ◽  
Marie L. Piketty ◽  
Roland M. Dardennes ◽  
Catherine Z. Musa

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