May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Histamine Inhibits Dopamine Release From Rat Retina
Author Affiliations & Notes
  • D. W. Marshak
    Dept of Neurobiology & Anatomy, University of Texas Medical School, Houston, Texas
  • L. Maybit, Jr.
    Dept of Neurobiology & Anatomy, University of Texas Medical School, Houston, Texas
  • P. K. Rao
    Dept of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas
  • N. Kumar
    Dept of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas
  • R. D. Glickman
    Dept of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas
  • Footnotes
    Commercial Relationships  D.W. Marshak, None; L. Maybit, None; P.K. Rao, None; N. Kumar, None; R.D. Glickman, None.
  • Footnotes
    Support  NIH Grants EY06472 and DK007676 and a grant from Research to Prevent Blindness
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 5792. doi:https://doi.org/
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      D. W. Marshak, L. Maybit, Jr., P. K. Rao, N. Kumar, R. D. Glickman; Histamine Inhibits Dopamine Release From Rat Retina. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5792. doi: https://doi.org/.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose: : The goal of these experiments was to learn how histaminergic input from the hypothalamus influences the processing of visual information in rat retina. Retinopetal axons containing histamine terminate in the inner plexiform layer, and histamine receptors are expressed by dopaminergic amacrine cells (Gastinger et al., 2001, 2006). Because histamine is released during the dark phase of the light cycle, it was expected to inhibit the release of dopamine, as it does in the guinea pig retina (Weber and Schlicker, 2001).

Methods: : A superfused rat eyecup was maintained in vitro, under a constant, mesopic background light. All experiments were conducted in the daytime. The tissue was superfused with Ames medium containing 10µm pargyline and 1µm nomifensine equilibrated with 95%O2/5%CO2. Histamine was applied for 20 min followed by a 50 min washout; light stimulated release was studied using a 3 Hz, photopic flashing light. All samples were collected into1M HClO4, 200µm ascorbic acid, and 20 µM 3,4 dihydroxy benzylamine (internal standard). Samples were concentrated using a solid phase extraction method (Raggi et al., 1999), and dopamine was measured by HPLC with electrochemical detection at +0.46 V referenced to Ag/AgCl. The lower limit of quantitation for this method was approximately 1 ng/ml.

Results: : The sample preparation and solid phase extraction methods had at least 85% recovery with respect to dopamine. The background light did not induce detectable dopamine release under these conditions. Flashing light stimulated release to 2.49 ± 1.17 ng/ml, on average (n = 6). The levels of dopamine in the superfusate after 1µM histamine, 2.70 ± 1.73 (n = 4), were not significantly different from the control values. The light stimulated component of dopamine release was completely inhibited by either 5 µM (n = 4) or 10 µM (n = 4) histamine (p < 0.001).

Conclusions: : At low micromolar concentrations, histamine clearly inhibited the release of endogenous dopamine from the rat retina. The histaminergic neurons fire tonically according to the sleep/wake cycle, with the highest rates at night in nocturnal animals such as rats (Saper et al., 2001). Because dopamine contributes to light adaptation (Witkovsky, 2004), we predict that histamine released from retinopetal axons promotes dark adaptation in rats.

Keywords: dopamine • neurotransmitters/neurotransmitter systems • amacrine cells 
×
×

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.

×