Beta-alanine acts on glycine receptors in the rat sacral dorsal commissural neurons.
Whole-cell current responses to bath application of beta-alanine (beta-ALA) were investigated in neurons acutely dissociated from the rat sacra! dorsal commissural nucleus (SDCN) using the nystatin perforated patch recording configuration under voltage-clamp conditions. beta-ALA activated inward currents in a concentration-dependent manner over the range of 10-3000 microM with an EC50 of 80.8 microM. The reversal potential of beta-ALA-activated currents (I beta-ALA) was close to the Cl- equilibrium potential. Strychnine and the chloride channel blocker picrotoxin suppressed the I beta-ALA in a concentration-dependent manner with the IC50 values of 0.19 microM and 343.6 microM, respectively. At the concentration of 3 microM, strychnine was sufficient to completely block 100 microM beta-ALA response, whereas it did not show a suppression of GABA response. In contrast, bicuculline, a potent GABAA receptor antagonist, at concentrations up to 10 microM, a dose that could block the GABA response completely, had little or no effect on I beta-ALA. Furthermore, the I beta-ALA was not affected by a preceding GABA response, but rather cross-desensitized with that evoked by glycine. The results indicate that beta-ALA activates the strychnine-sensitive glycine receptors in the SDCN neurons, and suggest that beta-ALA may act as a functional neurotransmitter in the mammalian SDCN.
Wang
Dian-Shi
DS
Department of Anatomy and K. K. Leung Brain Research Centre, Fourth Military Medical University, 17# West Changle Road, Xi'an, 710032, Shaanxi, China. dianshiw@yahoo.com
Zhu
Hai-Lei
HL
Li
Ji-Shuo
JS
D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018756:GABA Antagonists / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D007002:Hypoglossal Nerve / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D018009:Receptors, Glycine / Q000187:drug effects / Q000502:physiology*; D013331:Strychnine / Q000494:pharmacology; D015091:beta-Alanine / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D001640:Bicuculline; D018756:GABA Antagonists; D018684:Glycine Agents; D010852:Picrotoxin; D018009:Receptors, Glycine; D013331:Strychnine; D015091:beta-Alanine; D005680:gamma-Aminobutyric Acid