General and Comparative Endocrinology, 1978, Vol.35(2), pp.99-109
The effects of pineal removal on daily variations and levels of some liver and plasma metabolites were examined in the goldfish, Carassius auratus . Pinealectomy abolishes the liver glycogen daily variation and decreases hepatic glycogen levels in goldfish maintained on specific photoperiod regimes during spring and summer. Neither the daily variation nor the levels of hepatic glycogen are affected by pinealectomy during the fall. Pinealectomy alters the plasma glucose daily variation and increases the levels of this metabolite in fishes maintained on long photoperiods during the summer. During the fall the daily variation of plasma glucose is abolished by pinealectomy and blood sugar levels are decreased. The diurnal fluctuation of plasma lipid is altered by pinealectomy during the summer. Plasma lipid levels are elevated in pinealectomized fishes during winter, spring, and summer. The daily variation of liver lipid levels is altered by pinealectomy during the autumn. Melatonin treatment increases liver glycogen reserves in goldfish maintained on a long, but not a short, photoperiod during the spring. Plasma glucose levels are also elevated by melatonin treatment. Therefore, the pineal organ participates in regulating levels and daily variations of some metabolites. The influence of the pineal on metabolites varies with season and day length.
Medicine ; Anatomy & Physiology
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