THE ULTRASTRUCTURE OF RAT PINEALOCYTES AFTER ADMINISTRATION OF INTERLEUKIN-1-BETA

The ultrastructure of the rat pinealocytes was studied after administr ation of interleukin 1 beta. Four rats received two injections of inte rleukin 1 beta in a dose of 10 mu g/kg body weight (at 08:00 and 20:00 ), whereas other four rats received the solvent only. The animals were killed 90 min after the second injection, i.e., 1.5h after the onset of darkness. No significant differences were found neither in the cros s-sectional areas of pinealocytes nor in the relative volumes of mitoc hondria, Golgi apparatus, granular endoplasmic reticulum and lipid dro plets, nor in the number of dense-core vesicles after interleukin 1 be ta administration in comparison with control animals. Only the relativ e volume of lysosomes was lower in rats which received interleukin 1 b eta when compared to the controls. The results of the present study in dicate that interleukin 1 beta, in the dose which induced decrease in plasma melatonin level, did not significantly influence the ultrastruc ture of pineal cells.