Morphodynamic response of the rat light pinealocytes to an injection act. Implication of beta-adrenoreceptors.

The implication of beta-adrenoreceptor-mediated noradrenalin action on the reactive morphodynamic response of light pinealocytes (LP) to an injection act, conceived as a short-lasting stress attack, is reported. An injection act, realized by saline-injection, was manifested in the occurrence of clustered "dusk" and "bright" cells--the representative forms of functionally activated LP. The time-related incidence of these cells entities--the appearance of "dusk" and "bright" cells at 5 min, transitory domination of "bright" cells and the nadir of "dusk" cells at 20 min, sporadic recognition of "bright" cells, lack of "dusk" cells at 45 min and the absence of both cell forms at 180 min--displayed that LP-reactive response promptly appeared and rapidly ceased. The injection of beta-adrenoreceptor antagonist, propranolol, did not considerably alter the pattern of LP-reactive response proper for saline-injected rats at 5 min. The constant presence of "dusk" and "bright" cells, structurally changed in all the following time periods under investigation, showed that this drug disordered the course of LP-reactive response to an injection act. On the contrary, LP of resting state was not found to be affected. Estimating functionally, the present results indicate that beta-adrenoreceptor-mediated noradrenalin action is required to promote, maintain and accomplish the LP-reactive response to a short-lasting stress inducement.