Hormonal, behavioral, and thermoregulatory responses to bacterial lipopolysaccharide in captive and free-living white-crowned sparrows ( Zonotrichia leucophrys gambelii)

• Published in: Hormones and behavior 2006, Vol.49 (1), p.15-29
• Main Authors: Owen-Ashley, Noah T., Turner, Michael, Hahn, Thomas P., Wingfield, John C.
• Format: Article
• Language: English
• Subjects: Acute phase response; Acute-Phase Reaction - metabolism; Aggression - drug effects; Animal ethology; Animals; Anorexia; Aves; Bacteria; Behavior, Animal - drug effects; Behavioral psychophysiology; Biological and medical sciences; Body Temperature Regulation - drug effects; Body Weight - drug effects; Corticosterone; Corticosterone - blood; Female; Fever - chemically induced; Fever - physiopathology; Fundamental and applied biological sciences. Psychology; Glucocorticoids - metabolism; Hormones - blood; Hormones and behavior; Immune–endocrine interactions; Life-history tradeoffs; Lipopolysaccharide; Lipopolysaccharides - pharmacology; Luteinizing hormone; Male; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Seasons; Sex Characteristics; Sickness behavior; Sparrows - physiology; Territorial aggression; Vertebrata; Weight Loss - drug effects; White-crowned sparrow; Zonotrichia leucophrys gambelii
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2005.04.009

Exposing vertebrates to pathogenic organisms or inflammatory stimuli, such as bacterial lipopolysaccharide (LPS), activates the immune system and triggers the acute phase response. This response involves fever, alterations in neuroendocrine circuits, such as hypothalamo–pituitary–adrenal (HPA) and -gonadal (HPG) axes, and stereotypical sickness behaviors that include lethargy, anorexia, adipsia, and a disinterest in social activities. We investigated the hormonal, behavioral, and thermoregulatory effects of acute LPS treatment in a seasonally breeding songbird, the white-crowned sparrow ( Zonotrichia leucophrys gambelii) using laboratory and field experiments. Captive male and female sparrows were housed on short (8L:16D) or long (20L:4D) day lengths and injected subcutaneously with LPS or saline (control). LPS treatment activated the HPA axis, causing a rapid increase in plasma corticosterone titers over 24 h compared to controls. Suppression of the HPG axis occurred in long-day LPS birds as measured by a decline in luteinizing hormone levels. Instead of a rise in body temperature, LPS-injected birds experienced short-term hypothermia compared to controls. Birds treated with LPS decreased activity and reduced food and water intake, resulting in weight loss. LPS males on long days experienced more weight loss than LPS males on short days, but this seasonal effect was not observed in females. These results paralleled seasonal differences in body condition, suggesting that modulation of the acute phase response is linked to energy reserves. In free-living males, LPS treatment decreased song and several measures of territorial aggression. These studies highlight immune–endocrine–behavior interrelationships that may proximately mediate life-history tradeoffs between reproduction and defense against pathogens.