| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
There are several steps to develop fever. Those are production of endogenous pyrogen, production of prostaglandin E2 (PGE2), neuronal response to PGE2, driving the effectors for heat production and heat conservation. All of these setps are indispensable for the febrile response. Although ontogeny of fever has been studied by several groups, there is little information which step is critical for the ontogenical development of fever. In the present study, we focused on the development of PGE2 receptor and PGE2 sensitivity in the preotic area.
Development of PGE2 receptor
1. PGE2 receptor in the rat brain is fairly low at the late gestational stage.
2. From postnatal day 5 to day 7, PGE2 receptor rapidly and transiently increased throughout the brain. Until 2 week, PGE2 receptor gradually decreased except for several regions, in which high density of PGE2 receptor is present in adult rat.
3. The density of PGE2 receptor in the anterior wall of the third ventricle, a presumed action site of PGE2 in producing fever, is higher than the surrounding region from postnatal day 1 and gradually increased. In 5 weeks, the density reaches to the adult level.
Development of PGE2 sensitivity
1. Injection of 100 ng PGE2 into the preoptic area of 7 day-old rats yielded gradual increase of rectal temperature. The amplitude of fever was less than the that of adult rat.
2. When 7 day-old rats were pretreated with dichrofenac, a potent inhibitor of prostaglandin synthesis, the same dose of PGE2 increased rectal temperature rapidly and intesely, the amplitude being 2.5 ﾟC.
These results indicate that sensitivity to PGE2 and ability to produce PGE2 have been already present in 7 day-old rats.
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