Recovery of motor spontaneous activity after intranasal delivery of human recombinant erythropoietin in a focal brain hypoxia model induced by CoCl2 in rats

Neurotox Res. 2011 Aug;20(2):182-92. doi: 10.1007/s12640-010-9233-8. Epub 2010 Nov 30.

Abstract

Stroke is a major human health problem inducing long-term disability without any efficient therapeutic option being currently available. Under hypoxia, hypoxia-inducible factor-1α (HIF-1α) activates several genes as erythropoietin receptor (Epo-R) related with O(2) supply, and the multidrug-resistance gene (MDR-1) related with drug-refractory phenotype. Brain cortical injection of CoCl(2) produces focal hypoxia-like lesion with neuronal and glial alterations, as well as HIF-1α stabilization and MDR-1 overexpression. Intranasal (IN) drug delivery can by-pass blood-brain barrier (BBB) where MDR-1 is normally expressed. We evaluated the effects of IN-rHu-Epo administration on spontaneous motor activity (SMA) and the brain pattern expression of HIF-1α, MDR-1, and Epo-R in our cobalt-induced hypoxia model. Adult male Wistar rats were injected by stereotaxic surgery in frontoparietal cortex, with CoCl(2) (2 μl-50 mM; n = 20) or saline (controls; n = 20). Ten rats of each group were treated with IN-rHu-Epo 24 U or IN-saline. In addition, erythropoietic stimulation was evaluated by reticulocytes (Ret) account during three consecutive days, after intraperitoneal (i.p.)-recombinant-human Epo (rHu-Epo) (950 U; n = 6) or IN-rHu-Epo (24 U; n = 6) administration. SMA was evaluated by open field and rotarod tests, before and after surgical procedures during five consecutive days. Histological and immunostaining studies of HIF-1α, MDR-1, and Epo-R were performed on brain slides. A significant difference in SMA was observed in the hypoxic rats of IN-rHu-Epo-administered group as compared with Co-Saline-treated subjects and controls (p < 0.001). HIF-1α, EPO-R, and MDR-1 were overexpressed in the hypoxic cortex areas, while in contralateral hemisphere or controls, they were negatives. Reticulocytes were only increased in intraperitoneal (i.p.)-rHu-Epo-administered group. In spite of MDR-1 overexpression being detected in neurons, the coexpression of Epo-R could explain the positive effects observed on SMA of IN-rHu-Epo-administered group.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Administration, Intranasal
  • Analysis of Variance
  • Animals
  • Cobalt / toxicity*
  • Disease Models, Animal
  • Erythropoietin / administration & dosage*
  • Exploratory Behavior / drug effects*
  • Gene Expression Regulation / drug effects
  • Humans
  • Hypoxia, Brain / chemically induced*
  • Hypoxia, Brain / drug therapy*
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Male
  • Motor Activity / drug effects
  • Rats
  • Rats, Wistar
  • Receptors, Erythropoietin / metabolism
  • Recombinant Proteins
  • Recovery of Function / drug effects*
  • Reticulocytes / drug effects
  • Rotarod Performance Test

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Receptors, Erythropoietin
  • Recombinant Proteins
  • Erythropoietin
  • Cobalt
  • cobaltous chloride