Morphological changes of the adrenal gland following soft-laser irradiation of the pineal gland.

We present the results obtained in the adrenal gland of white rats (average weight 220 g) following irradiation of the pineal gland with laser light. Irradiation was carried out with a 5 mW Politec 750 Helium-Neon laser. Total irradiation time was 5 min, with rest intervals of 1 min for every minute of irradiation. Pineal gland irradiation was done under "open sky", i.e., directly at the gland. The effects of the suprarenal gland were studied 3, 7 and 10 d postirradiation. Morphological signs of an increasing activity have been observed in all layers of the cortex and in the medulla of the gland. The highest increase was found 7 d after irradiation in the fascicular zone and in the medulla, and after 3 d in the glomerular and reticular zone. We suggest that laser light induces an inhibitory effect observed at the suprarenal gland. This effect is similar to that found following pinealectomy, showing once again that the pineal gland exerts control on the suprarenal gland, mediated by luminous stimuli.