Abstract: | Glycogen, a polymer of α -D- glucose, represents the main reserve of glucides in animal organisms. The presence of glycogen has been evidenced in animal organisms, occurring in various stages of evolution.
The form in which glucides are being deposited in tissues is, on one side, represented by glucose - which is the circulating glucidic component - and, on the other, by glycogen - the reserve glucidic compound. Generally, besides lipids and proteins, glucides represent indispensable sources of metabolic energy. Under conditions of constant abundance of alimentary glucides, animal organisms use to stock such substances, either as hepatic and muscular glycogen (the immediate stock of energy), or by their conversion in lipids from the adipose tissues (the future energy stock).
In the case of fish, the normal values of muscular glycogen vary between 0.2 - 0.4 g %, while the values recorded by hepatic glycogen range between 7 and 11 g %; one has to observe here that, comparatively with mammals, these are much lower values.
In fish, an important characteristic of glycogen and glucose is their high sensitivity to stress, starvation and diseases, high growing densities, significant variations of temperature, modification of the normal values of such biochemical parameters being frequently considered in the diagnosis of such states (PETERS et al., 1981; PRICOPE et al., 1990; MISÃILÃ, 1998).
Lowering of the values of hepatic and muscular glycogen in fish under conditions of stress represents, besides the increase in glycemy, the response given by the organism, which mobilizes all its energetic sources for facing some accidental abnormal situations (DE DOMINIS et al., 1993; REHULKA, 1996). |
