title: β-adrenergic signaling regulates evolutionarily derived sleep loss in the Mexican cavefish.
abstract: Sleep is a fundamental behavior exhibited almost universally throughout the animal kingdom. The required amount and circadian timing of sleep differs greatly between species in accordance with habitats and evolutionary history. The Mexican blind cavefish, Astyanax mexicanus, is a model organism for the study of adaptive morphological and behavioral traits. In addition to loss of eyes and pigmentation, cave populations of A. mexicanus exhibit evolutionarily derived sleep loss and increased vibration attraction behavior, presumably to cope with a nutrient-poor environment. Understanding the neural mechanisms of evolutionarily derived sleep loss in this system may reveal critical insights into the regulation of sleep in vertebrates. Here we report that blockade of β-adrenergic receptors with propranolol rescues the decreased-sleep phenotype of cavefish. This effect was not seen with α-adrenergic antagonists. Treatment with selective β1-, β2-, and β3-antagonists revealed that the increased sleep observed with propranolol could partially be explained via the β1-adrenergic system. Morphological analysis of catecholamine circuitry revealed conservation of gross catecholaminergic neuroanatomy between surface and cave morphs. Taken together, these findings suggest that evolutionarily derived changes in adrenergic signaling underlie the reduced sleep of cave populations.
authors.affiliation: Department of Biology, New York University, New York, NY, USA.
authors.forename: Erik R
authors.initials: ER
authors.lastname: Duboué
authors.forename: Richard L
authors.initials: RL
authors.lastname: Borowsky
authors.forename: Alex C
authors.initials: AC
authors.lastname: Keene
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D005075:Biological Evolution; D001921:Brain / Q000378:metabolism; D059552:Caves; D002452:Cell Count / Q000379:methods / Q000706:statistics & numerical data; D060126:Characidae / Q000502:physiology*; D017753:Ecosystem; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D014446:Tyrosine 3-Monooxygenase