title: Morphine-conditioned cue alters c-Fos protein expression in the brain of crayfish.
abstract: With a highly organized stereotypic behavior and a simplified neuronal system that is characterized by cellular modularity, crayfish (Orconectes rusticus) represents an excellent model that we used in this study to explore how a drug-conditioned-cue alters c-Fos protein expression in the brain of an invertebrate species. The first set of experiments revealed that a single injection of different doses of morphine (3.0 μg/g, 6.0 μg/g and 12.0 μg/g) into the circulatory system of crayfish significantly increased locomotor activity. Repeated injections of morphine increased locomotion at lower doses (3.0 μg/g and 6.0 μg/g), and decreased locomotion at a higher dose of 12.0 μg/g. The second experiment revealed that a repeated or single injection of morphine serves as reward when paired with a distinct visual environment. In the third experiment, we found that the c-Fos profile of morphine treated crayfish in an unconditioned environment did not show a significant increase from the basal level comparable to saline treated crayfish. The brains of crayfish were more active during exposure to the cue-elicited drug conditioned environment than the unconditioned environment. These results indicate that chronic morphine treatment alone is not sufficient to induce changes in the expression of c-Fos; instead, morphine-environment pairing in a specific context contributes to the expression of alterations in c-Fos regulation. The enhancement of c-Fos expression in the brain of crayfish seems to reflect the sensory or anticipatory facets of conditioning that suggests that potential and even unanticipated hypotheses in drug addiction can emerge from studies of addiction in crayfish.
authors.affiliation: Center for Natural and Health Sciences, Marywood University, 2300 Adams Avenue, Scranton, PA 18509, USA.
authors.forename: Leah
authors.initials: L
authors.lastname: Dziopa
authors.forename: Adebobola
authors.initials: A
authors.lastname: Imeh-Nathaniel
authors.forename: Dana
authors.initials: D
authors.lastname: Baier
authors.forename: Michael
authors.initials: M
authors.lastname: Kiel
authors.forename: Sayeed
authors.initials: S
authors.lastname: Sameera
authors.forename: Adam
authors.initials: A
authors.lastname: Brager
authors.forename: Vega
authors.initials: V
authors.lastname: Beatriz
authors.forename: Thomas I
authors.initials: TI
authors.lastname: Nathaniel
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000033:anatomy & histology* / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D003213:Conditioning, Psychological / Q000187:drug effects*; D003463:Cues; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009294:Narcotics / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D011897:Random Allocation; D012201:Reward
chemical_list: D009294:Narcotics; D016760:Proto-Oncogene Proteins c-fos; D009020:Morphine