Changes in melatonin synthesis parameters after carbon monoxide concentration increase in the cavernous sinus

Area of Science:

• Ophthalmology
• Neuroendocrinology
• Chronobiology

Background:

• Carbon monoxide (CO) is released from the eye into ophthalmic venous blood, correlating with sunlight intensity.
• The role of CO as a potential carrier of light intensity information to regulate physiological processes remains unclear.

Purpose of the Study:

• To investigate if increased CO concentration in ophthalmic venous blood impacts melatonin synthesis.
• To determine if CO released from the eye under normal conditions can convey light intensity information.

Main Methods:

• Thirty-six male wild boar and pig crossbreeds were studied.
• Melatonin pathway response was measured by analyzing nocturnal melatonin levels after a 48-hour infusion of autologous blood plasma with a threefold increase in CO concentration in the ophthalmic venous sinus.
• Changes in AANAT protein levels were monitored concurrently.

Main Results:

• Increased CO concentration in ophthalmic venous blood significantly altered the duration and amplitude of the nocturnal melatonin peak.
• During winter, CO infusion limited the nocturnal melatonin rise; conversely, during summer, it enhanced the rise.
• Melatonin level fluctuations were consistently associated with parallel changes in AANAT protein levels.

Conclusions:

• Non-physiological increases in ocular CO concentration acutely affect systemic melatonin levels.
• These findings support the concept of humoral phototransduction, explaining some bright light effects in animal chronobiology.
• The study suggests potential implications for understanding and treating conditions like winter seasonal affective disorder.