Rat pinealocyte reactive response to a long-term stress inducement.

The pineal gland-reactive response to long-term multifactor stress inducement performed by 18 h immobilization was found in the occurrence of different pinealocyte forms--cells of the basal activity, functionally animated cells and cells assumed to be threatened by an irreversible injury. Functionally animated pinealocytes were recognized as entities of neuroendocrine-like and ependymal-like activities displaying an episode of their initially increased secretory activity determined by Golgi apparatus and succeeded by a period determined by the storage of compounds arising from the cisterns of the granular reticulum. The domination of the pinealocytes with neuroendocrine-like activity was considered to evince a stimulated, peptidergic-mediated pineal gland activity. The adrenocorticotropic hormone-reactive secretion, employed as the evaluation parameter in morphofunctional observations, corroborated the morphologically estimated increased pineal gland activity in long-term stress inducement.