Jpn. J. Pharmacol. 81 (2), 125-155 (1999)

Neuroactive Neurosteroids as Endogenous Effectors
for the Sigma1 (1) Receptor: Pharmacological Evidence
and Therapeutic Opportunities

Tangui Maurice1, Van-Ly Phan1, Alexandre Urani1, Hiroyuki Kamei2, Yukihiro Noda2 and Toshitaka Nabeshima2

1INSERM U. 336, Behavioral Neuropharmacology Group, ENSCM, 8, rue de l'Ecole Normale, 34296 Montpellier Cedex 5, France
2Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University School of Medicine, Tsuruma-cho, Nagoya 466 - 8560, Japan

Abstract: Neuroactive neurosteroids, including progesterone, allopregnanolone, pregnenolone and dehydroepiandrosterone, represent steroid hormones synthesized de novo in the brain and acting locally on nervous cells. Neurosteroids modulate several neurotransmitter systems such as -aminobutyric acid type A (GABAA), N-methyl-d-aspartate (NMDA) and acetylcholine receptors. As physiologic consequences, they are involved in neuronal plasticity, learning and memory processes, aggression and epilepsy, and they modulate the responses to stress, anxiety and depression. The 1-receptor protein was recently purified and its cDNA was cloned in several species. The amino-acid sequences are structurally unrelated to known mammalian proteins, but shared homology with a fungal sterol C8-C7 isomerase. The 1-receptor ligands exert a potent neuromodulation on excitatory neurotransmitter systems, including the glutamate and cholinergic systems. Consequently, selective 1 agonists show neuroprotective properties and beneficial effects in memory processes, stress and depression. The evidence of a direct interaction between neurosteroids and 1 receptors was first suggested by the ability of several steroids to inhibit the binding of 1receptor radioligands in vitro and in vivo. A crossed pharmacology between neurosteroids and 1-receptor ligands was described in several physiological tests and behavioral responses. This review will detail the recent evidence for a common mechanism of action between neurosteroids and 1-receptor ligands and focus on the potential therapeutic interests of such interaction in the physiopathology of learning and memory impairments, stress, depression and neuroprotection.

Keywords: Neurosteroid, Sigma1 receptor, Neuromodulation, Memory, Stress, Depression,
Pathological aging

Copyright The Japanese Pharmacological Society 1999

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