title: Tickling increases dopamine release in the nucleus accumbens and 50 kHz ultrasonic vocalizations in adolescent rats.
abstract: Adolescent rats emit 50 kHz ultrasonic vocalizations, a marker of positive emotion, during rough-and-tumble play or on tickling stimulation. The emission of 50 kHz ultrasonic vocalizations in response to tickling is suggested to be mediated by dopamine release in the nucleus accumbens; however, there is no direct evidence supporting this hypothesis. The present study aimed to elucidate whether play behavior (tickling) in adolescent rats can trigger dopamine release in the nucleus accumbens with hedonic 50 kHz ultrasonic vocalizations. The effect of tickling stimulation was compared with light-touch stimulation, as a discernible stimulus. We examined 35-40-day-old rats, which corresponds to the period of midadolescence. Tickling stimulation for 5 min significantly increased dopamine release in the nucleus accumbens (118±7% of the prestimulus control value). Conversely, light-touch stimulation for 5 min did not significantly change dopamine release. In addition, 50 kHz ultrasonic vocalizations were emitted during tickling stimulation but not during light-touch stimulation. Further, tickling-induced 50 kHz ultrasonic vocalizations were significantly blocked by the direct application of SCH23390 (D1 receptor antagonist) and raclopride (D2/D3 receptor antagonist) into the nucleus accumbens. Our study demonstrates that tickling stimulation in adolescent rats increases dopamine release in the nucleus accumbens, leading to the generation of 50 kHz ultrasonic vocalizations.
authors: Foundation for Advancement of International Science, Japan.
authors: Miyo
authors: M
authors: Hori
authors: Rie
authors: R
authors: Shimoju
authors: Ryota
authors: R
authors: Tokunaga
authors: Masato
authors: M
authors: Ohkubo
authors: Shigeki
authors: S
authors: Miyabe
authors: Junji
authors: J
authors: Ohnishi
authors: Kazuo
authors: K
authors: Murakami
authors: Mieko
authors: M
authors: Kurosawa
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D010988:Play and Playthings; D051381:Rats; D011919:Rats, Inbred Strains; D014465:Ultrasonics; D014828:Vocalization, Animal / Q000187:drug effects / Q000502:physiology*
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; C534628:SCH 23390; D004298:Dopamine