Daytime pineal gland activation in rats with colon tumors induced by 1,2-dimethylhydrazine(3).

OBJECTIVES

Intact rats and rats with 1,2-dimethylhydrazine induced tumors of large intestine were used in experiments. Previously, blood melatonin concentration in these tumor-bearing rats was shown to increase at night, but not in the daytime.

METHODS

The extracellular microelectrode registration of rat daytime pineal gland activity was performed.

RESULTS

The existence of different types of pinealocytes in the pineal gland was confirmed. Tumor-bearing rats, in comparison to intact, demonstrated higher spike frequency due to cells switching from regular to pattern (4-6 times gain) activity and appearance of "fast" cells (>5Hz frequency). CONSLUSIONS: The literature about pinealocytes points to the correlation between electrical and secretory processes in pinealocytes; thus we suppose the groups of interacting cells, detected in tumor-bearing rats, to reflect cascade cells activation while pineal gland secretion increases. The results indicate, that in the daytime pinealocytes are secreting substances (not melatonin) in dependence with hormonal background.