title: The strain of an accompanying conspecific affects the efficacy of social buffering in male rats.
abstract: Social buffering is a phenomenon in which stress in an animal is ameliorated when the subject is accompanied by a conspecific animal(s) during exposure to distressing stimuli. We previously reported that in male Wistar rats, the presence of another Wistar rat mitigates conditioned fear responses to an auditory conditioned stimulus (CS). Subsequent analyses revealed several characteristics of this social buffering of conditioned fear responses. However, information regarding the specificity of accompanying conspecifics is still limited. In the present study, we assessed whether rats of other strains could induce social buffering in Wistar rats. When a fear-conditioned Wistar subject was re-exposed to the CS alone, we observed increased freezing and decreased investigation and walking, as well as elevated corticosterone levels. The presence of a Wistar, Sprague-Dawley, or Long-Evans rat blocked these responses, suggesting that social buffering was induced by these strains of rats. In contrast, a Fischer 344 rat did not induce social buffering in the Wistar subject. We further found that an inbred Lewis rat induced social buffering whereas a Brown Norway rat, a strain that has been established independently from Wistar rats, did not. These results suggest that the difference in origin, rather than the inbred or outbred status of the associate rat, seemed to account for the lack of social buffering induced by the F344 rats. Based on these findings, we conclude that strains of an accompanying conspecific can affect the efficacy of social buffering in rats.
authors.affiliation: Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: kayopeche@gmail.com.
authors.forename: Kayo
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: 5202205938@mail.ecc.u-tokyo.ac.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Ishii
authors.affiliation: Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: akiyo@mail.ecc.u-tokyo.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kiyokawa
authors.affiliation: Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: aytake@mail.ecc.u-tokyo.ac.jp.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Takeuchi
authors.affiliation: Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: aymori@mail.ecc.u-tokyo.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mori
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology; D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D005239:Fear / Q000502:physiology / Q000523:psychology*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012919:Social Behavior; D012931:Social Environment; D013045:Species Specificity; D013315:Stress, Psychological / Q000523:psychology*
chemical_list: D003345:Corticosterone
keywords: Brown Norway; Conspecific buffering; Fear conditioning; Fischer 344; Strain differences