Abstract
The subfornical organ (SFO) that lacks blood-brain barrier has been presumed to one of the fever-related central nuclei, because lesion of the nucleus suppresses elevation of body core temperature following peripheral injection of pyrogens, and further there are receptors for lipolysacchalide and interleukins. The preoptic area and anterior hypothalamus (PO/AH) are very famous as the thermo-center, and there is thermosensitive neurons in the nuclei. However, no evidence demonstrates such property of SFO neurons. Therefore, we investigated effect of thermo-stimulation on spontaneous electrical activities of SFO neurons at slice preparations by using multi-electrodes MEA system, and compared with results of PO/AH neurons. By warm-stimulation from room temperature (23-26oC) to 40oC in recording chamber, almost SFO neurons (n = 11/13) were extremely excited from 30-33oC to 38oC and conversely inhibited over 39oC. The responses between 33oC and 37oC showed obviously Q10 > 2, indicating warm sensitivity in biology. On the other hand, in the PO/AH, warm sensitive neurons occupied only approximately 30-40% of neurons tested in the present study, as reported by many previous studies . These results suggest that the SFO has thermosensitivity as well as the PO/AH, but the ratio of warm-sensitive neurons is larger than that of the PO/AH that are generally known as thermo-center. [J Physiol Sci. 2007;57 Suppl:S181]
