Study of mast cell and histamine contents of the pineal body

Summary The number and distribution of mast cells were studied in pineal bodies of 16 mammalian species. In cattle, goat, monkey and guinea-pig the cells occurred in large numbers; in man, sheep, marmoset and mouse there was a moderate amount, and they were almost absent in pineal bodies of horse, rat, pig, dog, hamster, fox, cat and rabbit.In 17 human pineal bodies, 11 of which were obtained from normal individuals, the mast cell population was 3 ± 0.5 mast cells per microscopical field (0.32 mm in diameter).The histamine content in pineal bodies of several mammals was also determined. The substance occurred in high amount in the pineal body of cattle, in moderate amount in that of goat, man and sheep, and could not be detected in horse, pig, rabbit and rat.In human and cattle pineal bodies the histamine content could be correlated to the mast cell population; in other species the same correlation was only suggested.In in vitro experiments octylamine released histamine from the pineal body of cattle, while compound 48/80 was ineffective.It is suggested that the hypotensive action of pineal extract reported by several authors might be due to the histamine content of this gland.This work was supported in part by funds received from the Conselho Nacional de Pesquisas of Brazil and The Rockefeller Foundation (Grant 61119). — Acknowledgement. For encouragement and criticism the authors wish to express their gratitude to Prof. Dr. W. T. Beraldo (Department of Physiology) and Prof. Dr. L. J. A. Di Dio (Department of Anatomy).Fellow of the Conselho Nacional de Pesquisas of Brazil.