Seasonal changes in energy reserves in the common frog, Rana pipiens

Abstract

Seasonal changes in blood glucose content, liver glycogen content, and fat body weight have been studied in Rana pipiens. Over a 12-month period frogs were maintained at room temperature in tap water for a minimum of 14 days before observations were made. The frogs were not fed while in the laboratory. Blood glucose content was high in the summer (June through August) and fall (September through November) and low in the winter (December through February) and spring (March through May). The value for summer (60 mgm per 100 cm3 blood) was not significantly different from the blood glucose level in the fall (60 mgm % ). However, the blood glucose content in the winter (52 mgm % ) and the spring (49 mgm % ) were significantly different from each other and from the summer and fall. Liver glycogen content was high in the fall (1.16 gm/100 gm body weight). This decreased through the winter (0.85 gm/100 gm body weight) and spring (0.50 gm/100gm body weight) until the annual low was reached in the summer (0.27 gm/100 gm body weight). All seasons were significantly different from each other when tested statistically. Fat body weights also exhibited a seasonal variation. All seasons were significantly different from each other. The high was in the summer (203.3 mgm/100 gm body weight). Fat body weights then decreased to 87.1 mgm/100 gm body weight in the fall, 32.7 mgm/100 gm body weight in the winter, and 25.1 mgm/100 gm body weight in the spring. These data are important when studying metabolic changes in this common laboratory animal.

Mechanisms of changes to the liver pigmentary component during the annual cycle (activity and hibernation) of Rana esculenta L.

“…scavenging of reactive molecules such as free radicals), for the decrease in hepatocyte function, as characterized by an intense engagement in the storage of trophic materials (i.e. glycogen and lipids) (Mizell, 1965; Barni & Bernocchi, 1991; Fenoglio et al. 1992) as energy reserves during the fasting periods (Storey & Storey, 1988).…”

Increase in liver pigmentation during natural hibernation in some amphibians

“…This extension of liver pigmentation, in the sequence of active vs hypoactive phases, appears to correlate with functional modifications in the morphology of the liver parenchymal cells that during the winter are characterised by a decrease in metabolic activity and an increase in storage of trophic material, which is more intense in the frog than in newts (Barni & Bernocchi 1991 ;Fenoglio et al 1992 ;Barni et al 1994). Significant changes of the general metabolic activity have been found during the annual cycle particularly in anurans (Smith, 1950 ;Mizell, 1965 ;Rosenkilde & Jorgensen, 1977).…”

Growth in Amphibians

“…They aestivate in summer and hi bernate in winter. They show sexual varia tions in morphometric growth [23][24][25] and seasonal fluctuations in energy reserves [26,27], Therefore, a special skeletochronology technique has been developed, in addition to the standard size frequency histogram, to de termine the age structure of an amphibian population of a locality. Using the skeleto chronology technique, the layered structures found on the surface and in unstained ground sections of flat bones of amphibian skull re present the annual rate of growth [17,28,29], Ehrlich's haematoxylin staining is most suc cessful.…”