Premium
Mechanisms of changes to the liver pigmentary component during the annual cycle (activity and hibernation) of Rana esculenta L.
Author(s) -
Barni Sergio,
Vaccarone Rita,
Bertone Vittorio,
Fraschini Annunzia,
Bernini Franco,
Fenoglio Carla
Publication year - 2002
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1046/j.0021-8782.2001.00011.x
Subject(s) - hibernation (computing) , biology , rana , melanin , population , melanosome , microbiology and biotechnology , biochemistry , endocrinology , state (computer science) , demography , algorithm , sociology , computer science
The present study was performed to elucidate the mechanisms responsible for the changes of melanin content/distribution we had previously discovered in the liver parenchyma of Rana esculenta during natural hibernation. Melanomacrophagic component response was analysed using morphocytochemical methods. The results demonstrated that during the prehibernation period (October–November) the melanomacrophages reach the highest proliferative activity (BrdU, PCNA labelling) which is accompanied by an evident melanosynthesis (dopa‐oxidase activity). In contrast, after hibernation, the decrease of liver pigmentation was the consequence of a partial cell loss by apoptotic mechanisms (TUNEL labelling, pyknosis‐karyorhexis) accompanied by a decrease of melanosome content by autophagy and low melanosynthetic activity. On the basis of these findings, there is evidence that liver melanomacrophages represent a metabolically (melanin synthesis/degradation) and cytokinetically (proliferation/death) active cell population during the annual cycle of the frog. The results are also discussed in relation to the functional synergism between hepatocytes and pigment cells in the adaptation to environmental changes.