desensitization-recovery-crayfish-photoreceptors-upon-delivery-light

Desensitization and Recovery of Crayfish Photoreceptors Upon Delivery of a Light Stimulus

A method to study desensitization and recovery of crayfish photoreceptors is presented. We performed intracellular electrical recordings of photoreceptor ...

Universidad Nacional Autónoma de México

Visual photoreceptors are structures involved in the expression and synchronization of crayfish circadian rhythm of sensitivity to light (electroretinogram, ERG). Considering the relevant role of Pigment dispersing hormone (PDH) in the invertebrate circadian system organization, we study the effect of this substance on the electrical activity of crayfish visual photoreceptors during the 24-h cycle. The study demonstrates that: (1) PDH affects the electrical response to light of crayfish visual photoreceptor cells in a circadian time-dependent manner. (2) The kinetics of the light-elicited current of crayfish visual photoreceptor cells, as well as the ionic permeability underlying the electrical response to light vary over the 24-h cycle. (3) PDH modifies the kinetics and ionic permeability underlying the light-elicited current of crayfish visual photoreceptor cells in a circadian time-dependent manner.

Effect of pigment dispersing hormone on the electrical activity of crayfish visual photoreceptors during the 24-h cycle.

Celecoxib is a drug designed to selectively inhibit COX-2, an inflammation-inducible cyclooxygenase isoform, over the constitutively expressed COX-1 isoform. In addition to this selective inhibition it is now known that celecoxib exerts a variety of effects on several types of ion channels, thus producing secondary physiological effects. In this work we demonstrate that at therapeutically relevant concentrations celecoxib interacts with Shab K(+) channels specifically promoting a fast inactivation gating (without blocking the pore or significantly affecting other gating processes). At least two celecoxib molecules bind to each channel promoting a fast inactivation that develops from both open and closed states. Channel inactivation in turn causes a reduction of the size of I(K). Taken together, our observations show that in addition to its intended therapeutic target celecoxib is a useful tool to further study the mechanism of Shab channel inactivation.

Induction of a fast inactivation gating on delayed rectifier Shab K(+) channels by the anti-inflammatory drug celecoxib.

Mathematical models have been very useful in biological research. From the interaction of biology and mathematics, new problems have emerged that have generated advances in the theory, suggested further experimental work and motivated plausible conjectures. From our perspective, it is absolutely necessary to incorporate modeling tools in the study of circadian rhythms and that without a solid mathematical framework a real understanding of them will not be possible. Our interest is to study the main process underlying the synchronization in the pacemaker of a circadian system: these mechanisms should be conserved in all living beings. Indeed, from an evolutionary perspective, it seems reasonable to assume that either they have a common origin or that they emerge from similar selection circumstances. We propose a general framework to understand the emergence of synchronization as a robust characteristic of some cooperative systems of non-linear coupled oscillators. In a first approximation to the problem we vary the topology of the network and the strength of the interactions among oscillators. In order to study the emergent dynamics, we carried out some numerical computations. The results are consistent with experiments reported in the literature. Finally, we proposed a theoretical framework to study the phenomenon of synchronization in the context of circadian rhythms: the dissipative synchronization of nonautonomous dynamical systems. 

Article	Year
Effect of pigment dispersing hormone on the electrical activity of crayfish visual photoreceptors during the 24-h cycle. Comparative biochemistry and physiology. Part A, Molecular & integrative physiology\| PubMed ID: 20713169	2010
Induction of a fast inactivation gating on delayed rectifier Shab K(+) channels by the anti-inflammatory drug celecoxib. Channels (Austin, Tex.)\| PubMed ID: 21084865	2011
Modeling some properties of circadian rhythms. Mathematical biosciences and engineering : MBE\| PubMed ID: 24245720	2014

Carolina Barriga-Montoya

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