Estrogen and progesterone treatment: Effects on muscarinic M4 receptor subtype in the rat brain

Nahid K. El-Bakri, A. Adem, I. A. Suliman, E. Mulugeta, E. Karlsson, J. U. Lindgren, B. Winblad, A. Islam

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


We investigated the effect of ovariectomy (OVX) and hormonal treatment for 10 weeks by estradiol and progesterone on muscarinic M4 receptor subtype in different brain areas of female rats. Moreover, motor activity of OVX and hormone-treated rats was measured by automated open field exploration boxes. Receptor quantification in the hippocampus, frontal cortex, parietal cortex, amygdala and hypothalamus was done by receptor autoradiography using a selective ligand for muscarinic M4 receptors. Ovariectomy up-regulated M4 receptors in the dentate gyrus, CA1, CA3, frontal cortex and hypothalamus whereas the estrogen treatment restored M4 binding to that of the sham group. Progesterone treatment had no effect on the ovariectomy-induced up-regulation of M4 receptors. Ovariectomy significantly decreased the exploratory activity of the rats compared to the sham group. Estrogen treatment restored the exploratory behavior of the ovariectomized rats to that of the sham group whereas the progesterone-treated rats were less alert to the surrounding when compared to the sham and estrogen supplemented rats. The effect of estrogen on the hippocampal muscarinic M4 receptor subtype is a novel finding and may have functional significance for cholinergic receptors especially in relation to postmenopausal memory problems and neurodegenerative disease like Alzheimer's disease.

Original languageEnglish
Pages (from-to)131-137
Number of pages7
JournalBrain Research
Issue number1-2
Publication statusPublished - Sept 6 2002


  • Alzheimer's disease
  • Estrogen
  • Muscarinic receptor
  • Ovariectomy
  • Progesterone

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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