Seasonal variation in levels of prostaglandins D-2, E(2) and F-2 alpha in the brain of a mammalian hibernator, the Asian chipmunk

Seasonal changes in the in vivo levels of the prostaglandins (PGs) PGD(2), PGE(2), and PGF(2 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 PGD(2) 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 PGD(2) 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 PGD(2) and hibernation phenomenon. While PGE(2) level did not vary significantly throughout the year, PGF(2 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.