Gonadal hormones and frontocortical expression of vascular endothelial growth factor in male stroke-prone, spontaneously hypertensive rats, a model for attention-deficit/hyperactivity disorder

Endocrinology. 2004 Sep;145(9):4330-43. doi: 10.1210/en.2004-0487. Epub 2004 Jun 3.

Abstract

Attention-deficit/hyperactivity disorder (AD/HD) is a common pediatric behavioral disorder associated, in part, with male preponderance and reduced regional cerebral blood flow (rCBF). However, mechanism(s) underlying male preponderance and reduced rCBF in AD/HD are unclear. The present study profiles the expression of angiogenic and hormonal factors likely to underlie these symptoms using a recently characterized AD/HD animal model, juvenile male stroke-prone spontaneously hypertensive rats (SHRSP). Because vascular endothelial growth factor (VEGF) signaling cascade and gonadal steroids are key regulators of angiogenesis and gender-based behavior, respectively, we profiled their patterns of expression in the frontal cortex of SHRSP to elucidate their roles in the genesis of AD/HD male preponderance and rCBF. Interestingly, levels of VEGF, VEGF receptors (KDR, Flt-1), endothelial nitric oxide synthase, phosphorylated Akt (pAkt), estrogen receptor-alpha, aromatase, and capillary density in sham-operated SHRSP were remarkably down-regulated, whereas androgen receptor levels were up-regulated, compared with age-matched genetic control, Wistar-Kyoto rats. Castration, estrogen, and androgen receptor antagonist (flutamide) counteracted these effects. Dihydrotestosterone, but not testosterone, reversed the beneficiary effects of castration. Estrogen receptor-beta levels remained unchanged in all groups examined. We postulate that changes in androgen metabolism that tend to up-regulate local dihydrotestosterone concentration and diminish estrogen synthesis, in the frontal cortex of juvenile male SHRSP, may lower levels and/or activity of VEGF and its signaling cascade and, subsequently, reduce rCBF. These findings could, in part, help explain the pathogenesis of reduced rCBF and male preponderance in AD/HD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aromatase / genetics
  • Attention Deficit Disorder with Hyperactivity / physiopathology*
  • Capillaries / physiology
  • Cerebrovascular Circulation / physiology
  • Dihydrotestosterone / blood
  • Disease Models, Animal
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Estrogens / blood
  • Frontal Lobe / blood supply*
  • Gonadal Steroid Hormones / blood*
  • Hypertension / physiopathology*
  • Male
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase / genetics
  • Nitric Oxide Synthase Type III
  • Protein Serine-Threonine Kinases / genetics
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Rats, Inbred SHR
  • Rats, Inbred WKY
  • Receptors, Androgen / genetics
  • Receptors, Estrogen / genetics
  • Signal Transduction / physiology
  • Stroke / physiopathology
  • Testosterone / blood
  • Vascular Endothelial Growth Factor A / genetics*
  • Vascular Endothelial Growth Factor Receptor-1 / genetics
  • Vascular Endothelial Growth Factor Receptor-2 / genetics

Substances

  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Estrogens
  • Gonadal Steroid Hormones
  • Proto-Oncogene Proteins
  • Receptors, Androgen
  • Receptors, Estrogen
  • Vascular Endothelial Growth Factor A
  • Dihydrotestosterone
  • Nitric Oxide
  • Testosterone
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type III
  • Nos3 protein, rat
  • Aromatase
  • Vascular Endothelial Growth Factor Receptor-1
  • Vascular Endothelial Growth Factor Receptor-2
  • Akt1 protein, rat
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt