Seasonal variation in levels of prostaglandins D2, E2 and F2(alpha) in the brain of a mammalian hibernator, the Asian chipmunk.

Seasonal changes in the in vivo levels of the prostaglandins (PGs) PGD2, PGE2, and PGF2(alpha) were measured in the brain of the male Asian chipmunk, Tamias asiaticus (n = 111), which underwent hibernation during the period between November and March. The mean level of PGD2 ranged from 36.0 to 85.2 pg/g tissue from June to October and remained essentially unchanged (80.5 pg/g tissue) in December. However, the mean PGD2 level rose significantly to 128.6 pg/g tissue in February, and returned to 75.2 pg/g tissue in the following April, suggesting a correlation between PGD2 and hibernation phenomenon. While PGE2 level did not vary significantly throughout the year, PGF2(alpha), which appeared to be the most abundant among the three prostanoids, showed a marked circannual rhythm with a trough of 51.6 pg/g tissue in July, rising to 391.6 pg/g tissue in February and reaching the peak value of 492.7 pg/g tissue in April, the reproduction period.