Birdsong and the neural production of steroids.
The forebrain circuits involved in singing and audition (the 'song system') in songbirds exhibit a remarkable capacity to synthesize and respond to steroid hormones. This review considers how local brain steroid production impacts the development, sexual differentiation, and activity of song system circuitry. The songbird forebrain contains all of the enzymes necessary for the de novo synthesis of steroids - including neuroestrogens - from cholesterol. Steroid production enzymes are found in neuronal cell bodies, but they are also expressed in pre-synaptic terminals in the song system, indicating a novel mode of brain steroid delivery to local circuits. The song system expresses nuclear hormone receptors, consistent with local action of brain-derived steroids. Local steroid production also occurs in brain regions that do not express nuclear hormone receptors, suggesting a non-classical mode of action. Recent evidence indicates that local steroid levels can change rapidly within the forebrain, in a manner similar to traditional neuromodulators. Lastly, we consider growing evidence for modulatory interactions between brain-derived steroids and neurotransmitter/neuropeptide networks within the song system. Songbirds have therefore emerged as a rich and powerful model system to explore the neural and neurochemical regulation of social behavior.
Remage-Healey
Luke
L
Department of Physiological Science & Ecology and Evolutionary Biology, Brain Research Institute, University of California, Los Angeles, CA 90095, United States.
London
Sarah E
SE
Schlinger
Barney A
BA
D000818:Animals; D001717:Birds / Q000502:physiology*; D001923:Brain Chemistry / Q000502:physiology; D009420:Nervous System / Q000201:enzymology / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000096:biosynthesis* / Q000502:physiology; D011987:Receptors, Steroid / Q000502:physiology; D013256:Steroids / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology; D014828:Vocalization, Animal / Q000187:drug effects / Q000502:physiology*
D018377:Neurotransmitter Agents; D011987:Receptors, Steroid; D013256:Steroids