Circadian regulation of Limulus visual functions: A role for octopamine and cAMP
نویسنده
چکیده
The purpose of this contribution is to review our current understanding of the source and biochemistry of the circadian efferent input to the eyes of the American horseshoe crab Limulus polyphemus and the impact of this input on the structure, physiology and biochemistry of Limulus eyes. Special emphasis is given to the role of the biogenic amine octopamine and biochemical cascades it activates in the eyes. In addition to reviewing published data, we present new data showing that octopamine elevates cAMP levels in Limulus lateral eyes, and we partially characterize the pharmacology of the receptors involved in this response. We also present new data showing that octopamine regulates gene expression in Limulus lateral eyes by activating a cAMP cascade [Current Zoology 56 (5): 518–536, 2010].
منابع مشابه
Efferent neurotransmission of circadian rhythms in Limulus lateral eye. I. Octopamine-induced increases in retinal sensitivity.
Octopamine increases the sensitivity of the Limulus lateral eye in situ when injected beneath the cornea during the day. The effect of octopamine is dose-dependent with a threshold concentration of about 0.1 microM injected at 1 microliter/min for 15 min. Injection of 40 microM octopamine increases lateral eye sensitivity to approximately 70% of the nighttime level normally caused by the effere...
متن کاملVisual efference neuromodulates retinal timing: in vivo roles of octopamine, substance P, circadian phase, and efferent activation in Limulus.
Efferent nerves coursing from the brain to the lateral eye of the horseshoe crab, Limulus polyphemus, increase its nighttime sensitivity to light. They release octopamine, which produces a categorical increase of photoreceptor response duration in vitro. Analogous in vivo timing effects on the electroretinogram (ERG) were demonstrated when octopamine was infiltrated into the eye of an otherwise...
متن کاملOctopamine- and cyclic AMP-stimulated phosphorylation of a protein in Limulus ventral and lateral eyes.
The biogenic amine octopamine (OCT) fulfills most of the criteria as a neurotransmitter of efferent fibers that project to lateral and ventral eyes of the horseshoe crab, Limulus polyphemus. OCT is synthesized by and released from the efferent fibers, and OCT mimics many of the effects of endogenous efferent activity. OCT stimulates an increase in intracellular adenosine 3',5'-monophosphate (cA...
متن کاملOctopamine enhances dark-adaptation in Limulus ventral photoreceptors.
Limulus ventral photoreceptors receive synaptic input from fibers that emerge from the brain and that appear to use octopamine as a transmitter. Exogenous application of octopamine has been shown to increase levels of intracellular cAMP in ventral photoreceptors, but the resulting physiological effects have been unclear. In this report, we show that octopamine increases the rate of dark-adaptat...
متن کاملOctopamine Affects the Timing of Retinal Responses in Limulus as well as their Amplitudes
This magisterial article is concerned with the effects of octopamine modulation on the quantity of activity that occurs in a variety of well-studied model nervous systems. It particularly notes the effects of such neuromodulation on the magnitude of the responses found in the visual system of Limulus, the horseshoe crab. We here wish to note that such neuromodulation also affects the latencies ...
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تاریخ انتشار 2010