Hypothalamic and thalamic sites of action of interleukin-1β on food intake, body temperature and pain sensitivity in the rat

• Published in: Brain research 1995-10, Vol.694 (1), p.69-77
• Main Authors: Sellami, Souad, de Beaurepaire, Renaud
• Format: Article
• Language: English
• Subjects: Animals; Anorexia; Biochemistry and metabolism; Biological and medical sciences; Body Temperature - drug effects; Brain mapping; Central nervous system; Eating - drug effects; Female; Fever; Fundamental and applied biological sciences. Psychology; Hypothalamus; Hypothalamus - physiology; Interleukin-1 - pharmacology; Microinjection; Nociception; Pain Threshold - drug effects; Paraventricular Hypothalamic Nucleus - physiology; Paraventricular nucleus; Rats; Rats, Sprague-Dawley; Thalamus; Thalamus - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(95)00763-G

Interleukin-1β (IL-1β) has anorectic, hyperthermic, and analgesic or hyperalgesic (depending on the studies) effects in the rat. These effects appear to be mediated by the central nervous system; however, the exact localization of action of IL-1β in the brain has never been delineated with precision. The purpose of this study was to determine precisely where IL-1β acts in the hypothalamus and in the thalamus to modulate food intake, body temperature, and pain sensitivity. Animals were tested after local intracerebral microinjections of 5 ng of IL-1β dissolved in 0.3 μl of saline, or of 0.3 μl saline alone. The results show that IL-1β has anorectic effects in 3 diencephalic sites (the perifornical area, an area above the optic chiasma, and an area internal to the mamillo-thalamic tract), and not in 9 other sites tested. IL-1β has hyperthermic effects in 7 sites (the medial and lateral preoptic area, the hypothalamic periventricular substance, the dorso-medial and arcuate nuclei of the hypothalamus, and the centro-medial and gelatinosus nuclei of the thalamus), and not in 6 other sites. IL-1β has analgesic effects in the centro-medial and gelatinosus nuclei of the thalamus, and not in 7 other sites. IL-1β also increases food intake and decreases pain sensation thresholds in the paraventricular nucleus of the hypothalamus. Therefore IL-1β has very selective anatomical sites of action in the brain, and the paraventricular nucleus of the hypothalamus appears to have special properties regarding the effects of IL-1β on food intake and pain sensation regulation.