Tetrodotoxin instillation dose-dependently reduced nocturnal IOP by up to 103% ± 15% of elevation, and superior cervical ganglionectomy abolished the circadian IOP rhythm in rats.
Circadian IOP rhythm in rats is driven by sympathetic efferent signals from a central circadian clock, highlighting a neural pathway that may be relevant to glaucoma pathophysiology.
Effect estimate: TTX reduced nocturnal IOP up to 103% ± 15% of nocturnal elevation; SCGx abolished IOP circadian rhythm with no difference in IOP between subjective day and night (ΔIOP = 0.5 ± 0.3 mmHg, P=0.28)
Absolute Event Rate: -9% vs 0%
p-value: p=<0.001
The IOP rhythm in rats is driven by sympathetic efferent signals from a central circadian clock. Ocular clocks and circulating humoral factors do not appear to contribute to rhythmogenesis. The neural pathway of circadian pressure control may be relevant to glaucoma pathophysiology.
Zamitalo-Pomares et al. (Wed,) conducted a other in Circadian intraocular pressure rhythm in rats (n=14). Tetrodotoxin (TTX) instillation and superior cervical ganglionectomy (SCGx) vs. Saline instillation and pre-intervention baseline was evaluated on Circadian intraocular pressure (IOP) rhythm amplitude and presence during subjective night and day (TTX reduced nocturnal IOP up to 103% ± 15% of nocturnal elevation; SCGx abolished IOP circadian rhythm with no difference in IOP between subjective day and night (ΔIOP = 0.5 ± 0.3 mmHg, P=0.28), p=<0.001). Tetrodotoxin instillation dose-dependently reduced nocturnal IOP by up to 103% ± 15% of elevation, and superior cervical ganglionectomy abolished the circadian IOP rhythm in rats.