[Morphodynamic response of the pineal gland to an initial stress attack--the effect of morphine].

The possible participation of a stimulated ACTH secretion in the promotion of the pineal gland reactive response under conditions of injection stress was studied. Morphine was used as a pharmacological mimicry of the stress-induced ACTH outflow in the post-injection period of 10-45 min. In animals subjected to injection stress (administration of the physiological solution), in the 10-th min. light pinealocytes exhibited a significant rise in the relative volume of the GER field and the Gogli apparatus, as well as bouquets of presecretory or secretory forms of the cell processes and frequent extrusion of lipid droplets. From 20-th min. on, the relative volume of their membranous elaborative compartment gradually decreased, the cell processes were missing and the lipid droplet extrusion was rare. The rich arbourisation of the GER tubules, the active appearance of the Golgi apparatus and a more abundant occurrence of lipid droplets--a picture which persisted even in 30 min.--showed that the intensified elaborative activity of dark pinealocytes, a minor cell population, was of longer duration in comparison with light pinealocytes. The subsequent fall in their stress-reactive response points out that the function of light and dark pinealocytes is driven by different regulative systems. Based on the principle that the function is the reflection of morphometabolic changes, in can be concluded that 10 min. after the injection act, the pineal gland has a short-term crescendo of its stress-reactive response. The morphine injection did not cause any significant changes in both pinealocyte populations in 10 min. A considerable increase of the relative volume of the constituents of the membrane elaborative compartment was found in light pinealocytes in the next observational periods, i.e., in the 20-th and the 30-th min. The lack of any conspicuous signs of an enhanced secretory activity, in contrast with frequent findings of lipid droplets and prosecretory granules, shows that the facilitation of the elaborative activity leads more to a restitution and increase of the pinealocyte potential than to a stimulation of their current secretion. Characteristic of this period was a frequent finding of newly generated lipid droplets. Their presence within the fields of GER tubules, as well as the communication of the lumens of these tubules with the matrix of the arising lipid droplet suggest a close connection of lipid droplets with the pinealocyte peptidergic activity Unexpected was the finding of a conglomerate of fasciculated lamellae--structures of a so far unknown function.(ABSTRACT TRUNCATED AT 400 WORDS)