February 1986
Volume 27, Issue 2
Free
Articles  |   February 1986
Melatonin-binding in the frog retina: autoradiographic and biochemical analysis.
Investigative Ophthalmology & Visual Science February 1986, Vol.27, 153-163. doi:
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      A F Wiechmann, D Bok, J Horwitz; Melatonin-binding in the frog retina: autoradiographic and biochemical analysis.. Invest. Ophthalmol. Vis. Sci. 1986;27(2):153-163.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Binding of melatonin was examined in the retina of Rana pipiens. When intact frog retinas were incubated with 3H-melatonin and processed for autoradiography, most of the radioactivity was localized to the melanosomes of the retinal pigment epithelium-choroid (RPE-choroid) and to the outer plexiform layer of the retina. Melanosome-enriched fractions of the RPE-choroid and membrane-enriched fractions of the neural retina demonstrated saturable melatonin binding when incubated with increasing melatonin concentration. Thin-layer chromatography showed that greater than 98% of the bound radioactivity was authentic melatonin. Scatchard analysis revealed a single population of binding sites with apparent Kd values of 6 X 10(-7) M for both the RPE-choroid and neural retina. When various indole analogs were tested for their ability to inhibit 3H-melatonin binding to the neural retina, both 5-methoxytryptophol and 6-chloromelatonin demonstrated complete displacement of melatonin binding. Endogenous retinal melatonin levels were measured by radioimmunoassay. A twofold increase in melatonin levels was observed during the dark period with peak levels at 384.5 +/- 28.8 pgms melatonin/pair retinas. Melatonin levels persisted in constant darkness, but were suppressed in constant light. Our data suggest that in the frog, the sites of action of retinal melatonin are the melanosomes of the RPE-choroid and the outer plexiform layer of the neural retina.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×