Abstract
ABSTRACT. Phototherapy of newborn rats (NBR) resulted in a decrease in serum calcium and melatonin levels. Transcranial light penetrance in NBR increased with wavelength. Below 640 nm (penetrance = 6.9%), no hypocalcemic effect could be demonstrated. Shielding the occiput of NBR prevented a decrease in serum calcium during phototherapy and substantially reduced the decrease in melatonin found in unshielded NBR. Intraperitoneal injection of propranolol, an inhibitor of melatonin synthesis, caused a decrease in serum calcium in shaded NBR. In contrast, when melatonin was injected with propranolol a decrease in serum calcium did not occur. Additionally, intraperitoneal isoproterenol before phototherapy protected against a decrease in serum calcium. These data are consistent with an hypothesis that a decrease in serum calcium during phototherapy results from transcranial photic inhibition of melatonin synthesis.
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Hakanson, D., Penny, R. & Bergstrom, W. Calcemic Responses to Photic and Pharmacologic Manipulation of Serum Melatonin. Pediatr Res 22, 414–416 (1987). https://doi.org/10.1203/00006450-198710000-00010
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DOI: https://doi.org/10.1203/00006450-198710000-00010
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