Skip to main content
PMC home page
Neurotherapeutics logoLink to Neurotherapeutics
. 2009 Apr;6(2):372–380. doi: 10.1016/j.nurt.2009.01.001

Developing novel antiepileptic drugs: Characterization of NAX 5055, a systemically-active galanin analog, in epilepsy models

H Steve White 1,2,✉, Erika A Scholl 3, Brian D Klein 4, Sean P Flynn 1, Timothy H Pruess 1, Brad R Green 3, Liuyin Zhang 3, Grzegorz Bulaj 3
PMCID: PMC4402707  NIHMSID: NIHMS108786  PMID: 19332332

Summary

The endogenous neuropeptide galanin and its associated receptors galanin receptor 1 and galanin receptor 2 are highly localized in brain limbic structures and play an important role in the control of seizures in animal epilepsy models. As such, galanin receptors provide an attractive target for the development of novel anticonvulsant drugs. Our efforts to engineer galanin analogs that can penetrate the blood-brain-barrier and suppress seizures, yielded NAX 5055 (Gal-B2), a systemically-active analog that maintains low nanomolar affinity for galanin receptors and displays a potent anticonvulsant activity. In this report, we show that NAX 5055 is active in three models of epilepsy: 1) the Frings audiogenic seizure-susceptible mouse, 2) the mouse corneal kindling model of partial epilepsy, and 3) the 6 Hz model of pharmacoresistant epilepsy. NAX 5055 was not active in the traditional maximal electroshock and subcutaneous pentylenetetrazol seizure models. Unlike most antiepileptic drugs, NAX 5055 showed high potency in the 6 Hz model of epilepsy across all three different stimulation currents; i.e., 22, 32 and 44 mA, suggesting a potential use in the treatment of pharmacoresistant epilepsy. Furthermore, NAX 5055 was found to be biologically active after intravenous, intraperitoneal, and subcutaneous administration, and efficacy was associated with a linear pharmacokinetic profile. The results of the present investigation suggest that NAX 5055 is a first-in-class neurotherapeutic for the treatment of epilepsy in patients refractory to currently approved antiepileptic drugs.

Key Words: Neuropeptide, anticonvulsant drug, audiogenic seizures, 6 Hz seizure, corneal kindled mouse

References

  • 1.Baraban SC, Tallent MK. Interneuron diversity series: interneuronal neuropeptides—endogenous regulators of neuronal excitability. Trends Neurosci. 2004;27:135–142. doi: 10.1016/j.tins.2004.01.008. [DOI] [PubMed] [Google Scholar]
  • 2.Hokfelt T, Broberger C, Xu ZQ, Sergeyev V, Ubink R, Diez M. Neuropeptides—an overview. Neuropharmacology. 2000;39:1337–1356. doi: 10.1016/S0028-3908(00)00010-1. [DOI] [PubMed] [Google Scholar]
  • 3.Waxham N. Neuropeptides and nitric oxide. In: Byrne JH, ed. Neuroscience Online, 2007. Available at: http://neuroscience.uth.tmc.edu. Accessed July 15, 2007.
  • 4.Gundlach AL, Jungnickel R-F. Galanin and GALP systems in brain — molecular pharmacology, anatomy, and putative roles in physiology and pathology. In: Kastin AJ, editor. Handbook of biologically active peptides. Amsterdam: Elsevier; 2006. pp. 753–761. [Google Scholar]
  • 5.Hawes JJ, Picciotto MR. Characterization of GalR1, GalR2, and GalR3 immunoreactivity in catecholaminergic nuclei of the mouse brain. J Comp Neurol. 2004;479:410–423. doi: 10.1002/cne.20329. [DOI] [PubMed] [Google Scholar]
  • 6.Goiter JA, van Vliet EA, Aronica E, et al. Potential new antiepileptogenic targets indicated by microarray analysis in a rat model for temporal lobe epilepsy. J Neurosci. 2006;26:11083–11110. doi: 10.1523/JNEUROSCI.2766-06.2006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Mazarati AM, Halaszi E, Telegdy G. Anticonvulsive effects of galanin administered into the central nervous system upon the picrotoxin-kindled seizure syndrome in rats. Brain Res. 1992;589:164–166. doi: 10.1016/0006-8993(92)91179-I. [DOI] [PubMed] [Google Scholar]
  • 8.Gu XL, Sun YG, Yu LC. Involvement of galanin in nociceptive regulation in the arcuate nucleus of hypothalamus in rats with mononeuropathy. Behav Brain Res. 2007;179:331–335. doi: 10.1016/j.bbr.2007.02.033. [DOI] [PubMed] [Google Scholar]
  • 9.Kanter-Schlifke I, Toft Sørensen A, Ledri M, Kuteeva E, Hökfelt T, Kokaia M. Galanin gene transfer curtails generalized seizures in kindled rats without altering hippocampal synaptic plasticity. Neuroscience. 2007;150:984–992. doi: 10.1016/j.neuroscience.2007.09.056. [DOI] [PubMed] [Google Scholar]
  • 10.Wynick D, Bacon A. Targeted disruption of galanin: new insights from knock-out studies. Neuropeptides. 2002;36:132–144. doi: 10.1054/npep.2002.0888. [DOI] [PubMed] [Google Scholar]
  • 11.Kokaia M, Holmberg K, Nanobashvili A, et al. Suppressed kindling epileptogenesis in mice with ectopic overexpression of galanin. Proc Natl Acad Sci U S A. 2001;98:14006–14011. doi: 10.1073/pnas.231496298. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Liu HX, Brumovsky P, Schmidt R, et al. Receptor subtype-specific pronociceptive and analgesic actions of galanin in the spinal cord: selective actions via GalR1 and GalR2 receptors. Proc Natl Acad Sci U S A. 2001;98:9960–9964. doi: 10.1073/pnas.161293598. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13.Mahoney SA, Hosking R, Fanant S, et al. The second galanin receptor GalR2 plays a key role in neurite outgrowth from adult sensory neurons. J Neurosci. 2003;23:416–421. doi: 10.1523/JNEUROSCI.23-02-00416.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Branchek TA, Smith KE, Gerald C, Walker MW. Galanin receptor subtypes. Trends Pharmacol Sci. 2000;21:109–117. doi: 10.1016/S0165-6147(00)01446-2. [DOI] [PubMed] [Google Scholar]
  • 15.Lundstrom L, Elmquist A, Bartfai T, Langel U. Galanin and its receptors in neurological disorders. Neuromolecular Med. 2005;7:157–180. doi: 10.1385/NMM:7:1-2:157. [DOI] [PubMed] [Google Scholar]
  • 16.Lu X, Lundstrom L, Langel U, Bartfai T. Galanin receptor ligands. Neuropeptides. 2005;39:143–146. doi: 10.1016/j.npep.2004.12.012. [DOI] [PubMed] [Google Scholar]
  • 17.Bulaj G, Green BR, Lee H-K, et al. Design, synthesis and characterization of high-affinity, systemically-active galanin analogs with potent anticonvulsant activities. J Med Chem. 2008;51:8038–8047. doi: 10.1021/jm801088x. [DOI] [PubMed] [Google Scholar]
  • 18.White HS, Watson WP, Hansen SL, et al. First demonstration of a functional role for central nervous system betaine/(gamma)-aminobutyric acid transporter (mGAT2) based on synergistic anticonvulsant action among inhibitors of mGAT1 and mGAT2. J Pharmacol Exp Ther. 2005;312:866–874. doi: 10.1124/jpet.104.068825. [DOI] [PubMed] [Google Scholar]
  • 19.Barton ME, Klein BD, Wolf HH, White HS. Pharmacological characterization of the 6 Hz psychomotor seizure model of partial epilepsy. Epilepsy Res. 2001;47:217–227. doi: 10.1016/S0920-1211(01)00302-3. [DOI] [PubMed] [Google Scholar]
  • 20.Matagne A, Klitgaard H. Validation of comeally kindled mice: a sensitive screening model for partial epilepsy in man. Epilepsy Res. 1998;31:59–71. doi: 10.1016/S0920-1211(98)00016-3. [DOI] [PubMed] [Google Scholar]
  • 21.Woodbury LA, Davenport VD. Design and use of a new electro-shock seizure apparatus, and analysis of factors altering seizure threshold and pattern. Arch Int Pharmacodyn Ther. 1952;92:97–104. [PubMed] [Google Scholar]
  • 22.Brown WC, Schiffman DO, Swinyard EA, Goodman LS. Comparative assay of antiepileptic drugs by “psychomotor” seizure test and minimal electroshock threshold test. J Pharmacol Exp Ther. 1953;107:273–283. [PubMed] [Google Scholar]
  • 23.Matagne A, Klitgaard H. Validation of comeally kindled mice: a sensitive screening model for partial epilepsy in man. Epilepsy Res Suppl. 1998;31:59–71. doi: 10.1016/S0920-1211(98)00016-3. [DOI] [PubMed] [Google Scholar]
  • 24.Racine RJ. Modification of seizure activity by electrical stimulation. II. Motor seizure. Electroencephalogr Clin Neurophysiol. 1972;32:281–294. doi: 10.1016/0013-4694(72)90177-0. [DOI] [PubMed] [Google Scholar]
  • 25.Dunham MS, Miya TA. A note on a simple apparatus for detecting neurological deficit in rats and mice. J Amer Pharm Ass Sci Ed. 1957;46:208–209. doi: 10.1002/jps.3030460322. [DOI] [PubMed] [Google Scholar]
  • 26.Finney DJ. Probit Analysis. 3rd ed. London: Cambridge University Press; 1971. [Google Scholar]
  • 27.Lang R, Gundlach AL, Kofier B. The galanin peptide family: receptor pharmacology, pleiotropic biological actions, and implications in health and disease. Pharmacol Ther. 2007;115:177–207. doi: 10.1016/j.pharmthera.2007.05.009. [DOI] [PubMed] [Google Scholar]
  • 28.Lerner JT, Sankar R, Mazarati AM. Galanin and epilepsy. Cell Mol Life Sci. 2008;65:1864–1871. doi: 10.1007/s00018-008-8161-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Mitsukawa K, Lu X, Bartfai T. Galanin, galanin receptors and drug targets. Cell Mol Life Sci. 2008;65:1796–1805. doi: 10.1007/s00018-008-8153-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Heinemann U, Schmitz D, Eder C, Gloveli T. Properties of entorhinal cortex projection cells to the hippocampal formation. Ann N Y Acad Sci. 2000;911:112–126. doi: 10.1111/j.1749-6632.2000.tb06722.x. [DOI] [PubMed] [Google Scholar]
  • 31.Mazarati A, Lundstrom L, Sollenberg U, Shin D, Langel U, Sankar R. Regulation of kindling epileptogenesis by hippocampal galanin type 1 and type 2 receptors: The effects of subtype-selective agonists and the role of G-protein-mediated signaling. J Pharmacol Exp Ther. 2006;318:700–708. doi: 10.1124/jpet.106.104703. [DOI] [PubMed] [Google Scholar]
  • 32.Bartfai T, Lu X, Badie-Mahdavi H, et al. Galmic, a nonpeptide galanin receptor agonist, affects behaviors in seizure, pain, and forced-swim tests. Proc Natl Acad Sci U S A. 2004;101:10470–10475. doi: 10.1073/pnas.0403802101. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Saar K, Mazarati AM, Mahlapuu R, et al. Anticonvulsant activity of a nonpeptide galanin receptor agonist. Proc Natl Acad Sci U S A. 2002;99:7136–7141. doi: 10.1073/pnas.102163499. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.Klitgaard H, Matagne A, Gobert J, Wulfert E. Evidence for a unique profile of levetiracetam in rodent models of seizures and epilepsy. Eur J Pharmacol. 1998;353:191–206. doi: 10.1016/S0014-2999(98)00410-5. [DOI] [PubMed] [Google Scholar]
  • 35.Loscher W, Honack D. Profile of ucb L059, a novel anticonvulsant drug, in models of partial and generalized epilepsy in mice and rats. Eur J Pharmacol. 1993;232:147–158. doi: 10.1016/0014-2999(93)90768-D. [DOI] [PubMed] [Google Scholar]
  • 36.Loscher W. Animal models of epilepsy for the development of anti-epileptogenic and disease-modifying drugs. A comparison of the pharmacology of kindling and post-status epilepticus models of temporal lobe epilepsy. Epilepsy Res. 2002;50:105–123. doi: 10.1016/S0920-1211(02)00073-6. [DOI] [PubMed] [Google Scholar]
  • 37.Stables JP, Bertram EH, White HS, et al. Models for epilepsy and epileptogenesis: report from the NIH workshop, Bethesda, Maryland. Epilepsia. 2002;43:1410–1420. doi: 10.1046/j.1528-1157.2002.06702.x. [DOI] [PubMed] [Google Scholar]
  • 38.Wrenn CC, Holmes A. The role of galanin in modulating stress-related neural pathways. Drug news & perspectives. 2006;19:461–467. doi: 10.1358/dnp.2006.19.8.1043963. [DOI] [PubMed] [Google Scholar]
  • 39.Hygge-Blakeman K, Brumovsky P, Hao JX, et al. Galanin over-expression decreases the development of neuropathic pain-like behaviors in mice after partial sciatic nerve injury. Brain research. 2004;1025:152–158. doi: 10.1016/j.brainres.2004.07.078. [DOI] [PubMed] [Google Scholar]
  • 40.Liu H, Hokfelt T. Effect of intrathecal galanin and its putative antagonist M35 on pain behavior in a neuropathic pain model. Brain research. 2000;886:67–72. doi: 10.1016/S0006-8993(00)02791-8. [DOI] [PubMed] [Google Scholar]
  • 41.Wiesenfeld-Hallin Z, Xu XJ, Langel U, Bedecs K, Hokfelt T, Bartfai T. Galanin-mediated control of pain: enhanced role after nerve injury. Proceedings of the National Academy of Sciences of the United States of America. 1992;89:3334–3337. doi: 10.1073/pnas.89.8.3334. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 42.Fisone G, Berthold M, Bedecs K, et al. N-terminal galanin-(1–16) fragment is an agonist at the hippocampal galanin receptor. Proceedings of the National Academy of Sciences of the United States of America. 1989;86:9588–9591. doi: 10.1073/pnas.86.23.9588. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Land T, Langel U, Low M, Berthold M, Unden A, Bartfai T. Linear and cyclic N-terminal galanin fragments and analogs as ligands at the hypothalamic galanin receptor. International journal of peptide and protein research. 1991;38:267–272. doi: 10.1111/j.1399-3011.1991.tb01438.x. [DOI] [PubMed] [Google Scholar]
  • 44.Stohr T, Kupferberg HJ, Stables JP, et al. Lacosamide, a novel anti-convulsant drug, shows efficacy with a wide safety margin in rodent models for epilepsy. Epilepsy research. 2007;74:147–154. doi: 10.1016/j.eplepsyres.2007.03.004. [DOI] [PubMed] [Google Scholar]

Articles from Neurotherapeutics are provided here courtesy of Elsevier

RESOURCES