研究者詳細 - 名倉　悟郎

Long-term behavioral effects of social separation during early life in a social mammal, Octodon degus

Ukyo R., Shinohara A., Koshimoto C., Nagura-Kato G.A., Ieiri S., Tsuzuki Y., Sakamoto S.H.

Scientific Reports 13 ( 1 ) 9518 2023年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Scientific Reports

Social separation is thought to induce a strong stress response in social juvenile mammals, but little is known about how this response might vary throughout the development. The present study examines the long-term effects of early-life stress (ELS) induced by social separation on individual behaviors later in life using the social and precocious species Octodon degus. Four experimental groups were established a positive control group of mothers and siblings from six litters comprised the socially housed (SH) group, while pups from seven litters were randomly assigned to three treatments: pups experiencing no separation (NS) treatment while their siblings did; repeated bouts of consecutive separation (CS); intermittent separation (IS). We analyzed the effects of separation treatment on the frequency and duration of freezing, rearing and grooming behaviors. ELS was correlated with higher hyperactivity, and hyperactivity increased with more frequent separation. However, the behavioral trend of the NS group changed to hyperactive in long-term observation. The findings suggest that the NS group was indirectly affected by ELS. In addition, suggesting ELS acts to converge an individual’s behavioral tendencies in a certain direction.

DOI： 10.1038/s41598-023-36745-6

Message to researchers: the characteristic absence of a posterior communicating artery is easily lost in the gerbil

Abe Y., Toyama K., Shinohara A., Nagura-Kato G.A., Ikai Y., Koshimoto C., Spin J.M., Hato N.

Anatomical Science International 98 ( 3 ) 426 - 433 2023年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Anatomical Science International

The Mongolian gerbil has historically been useful for brain ischemia experiments, owing to the gerbil’s uniquely underdeveloped circle of Willis (CoW). This led to a gerbil model of cochlear ischemia being generated in our unit. However, we have found that the usual severe hearing loss seen in this model was not being induced consistently in recent experiments using the MON/Jms/GbsSlc gerbil (the sole commercially available gerbil in Japan). We set out to evaluate the posterior communicating artery (PcomA) in MON/Jms/GbsSlc, to re-establish whether this strain is appropriate for ischemia models. Having found that this unique feature is often lost, we then attempted to breed for the characteristic absent PcomA. India-ink perfusion revealed that the percentage of intact bilateral PcomA (“communicating type”) in the MON/Jms/GbsSlc gerbil was 57%; unilateral only (“unilateral communicating type”) was 39%; and completely absent PcomA (“non-communicating type”) was 4%. We were able to obtain few examples of the indigenous old aged Japanese UNG/Mz gerbil strain (at University of Miyazaki). Unfortunately, the pure UNG/Mz female was too elderly for mating. Therefore, selective breeding crosses between MON/Jms/GbsSlc and male UNG/Mz were carried out. After five generations of selective breeding, the percentage of non-communicating type gerbils was significantly higher in the newly generated strain, MON/Jms/SlcMz (F6 generation; 63%) than in the MON/Jms/GbsSlc gerbil. Bilateral common carotid artery occlusion surgery demonstrated that the cerebral blood flow was significantly reduced in MON/Jms/SlcMz compared with MON/Jms/GbsSlc (p < 0.0001) and induced more hippocampal injuries in MON/Jms/SlcMz than in MON/Jms/GbsSlc (p < 0.01). In conclusion, the commercially available MON/Jms/GbsSlc gerbil can easily regain PcomA, and we established a new gerbil strain (MON/Jms/SlcMz) displaying non-PcomA.

DOI： 10.1007/s12565-022-00698-z

脳波測定を活用したデグー（Octodon degus）のセボフルラン及びイソフルラン吸入麻酔特性の検討. 招待あり

伊海結貴，七條宏樹，名倉悟郎，篠原明男，越本知大.

九州実験動物雑誌 36 53 - 55 2021年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）

Dietary protein deficiency affects food consumption and torpor in the African woodland dormouse (Graphiurus murinus) 査読あり

Takeshi Eto, Sayako Hidaka, Hiroki Shichijo, Goro A. Nagura-Kato and Tetsuo Morita

Mammal Study 47 ( 1 ) 2021年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Mammalogical Society of Japan

Abstract. Many heterotherms employ torpor to conserve energy to cope with food shortage. Food shortage affects not only energy budgets but also other aspects of nutritional status. In addition to serving as an energy substrate, dietary proteins also provide vital nutrients including essential amino acids, some of which cannot be synthesized de novo. We evaluated the hypothesis that dietary protein deficiency induces torpor as a means of adjusting protein metabolism in the African woodland dormouse (Graphiurus murinus), a rodent with a protein-rich diet and lacking a cecum, which limits the potential for hindgut fermentation and coprophagy. Dormice were fed control and non-protein diets with equivalent energy content every two weeks under thermoneutral conditions. While the dormice did not express torpor under control conditions, some did under protein-deficient conditions. Among dormice expressing torpor, one maintained energy intake comparable to that during the control diet period, whereas the other reduced energy intake due to spontaneously reduced food consumption. These results suggest that torpor can be induced directly or indirectly by dietary protein deficiency even in the absence of energy constraints and thermal stress. In either case, torpor in response to deficiency in certain nutrients can reduce demands of the nutrient.

DOI： 10.3106/ms2020-0102

デグー（Octodon degus）に観察されるてんかん様発作の評価指標

伊海結貴, 篠原明男, 名倉（加藤）悟郎, 七條宏樹, 越本知大

哺乳類科学 61 ( 1 ) 3 - 11 2021年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：日本哺乳類学会

デグーOctodon degusは南米原産の草食性齧歯類で，個体間での優れた音声コミュニケーションや道具機能の理解など，他の齧歯類に見られないユニークな特徴をもつ．近年ではこうした特徴が脳の高次機能と関連付けられ，主に医科学，行動心理学の分野で脳の発達やアルツハイマー病態の解明に有用なバイオリソースとしての特性把握が進められている．今回我々は宮崎大学において系統管理を続けているデグー集団内に「てんかん様発作」を示す個体を見出した．調べる限りデグーのてんかん様発作に関する報告はなく，その症状を精査することで，我々は新たな研究資源の創出の可能性を提示できると考えた．そこで本研究ではデグーのてんかん様発作症状を臨床的に評価する為の客観的指標を作成することを目的として，動画観察による発作の過程と強度，更には総持続時間の評価を試みた．デグー16頭（雌：雄＝7：9）が呈した合計35回のてんかん様発作を撮影した動画を解析した結果，デグーのてんかん様発作は体の一部の異常（過程1）に始まり，続く全身の強直様症状とけいれん（過程2），短時間の静止状態（過程3），そして再び体の強直様症状とけいれん以外の異常（過程4）を経て，静止状態（過程5）の後に健常な状態を回復するという一連の過程を辿る事が示された．マウスやラットより複雑な脳機能をもつと考えられるデグーは新たなてんかんモデル動物としての可能性を有すると考えられ，本研究で初めて作成した指標はデグーに観察されるてんかん様発作の評価基準として活用できる．また本研究では，発作の強度や総持続時間には性差があることが示唆されたが，一方で発作の頻度そのものに著しい個体差が見られたことから，今後の追加検討が急務である．

DOI： 10.11238/mammalianscience.61.3

マウスの兄妹関係がもたらす影響とは？個体差に隠された謎を考える

名倉悟郎

実験動物ニュース Vol. 69 No. 3 117 - 119 2020年

掲載種別：研究論文（学術雑誌）

Comparison of the gut microbiotas of laboratory and wild asian house shrews (Suncus murinus) based on cloned 16s rRNA sequences

ヨーロッパモリネズミにおける尿を用いたストレスホルモンの測定

前山健太、篠原明男、仮屋博敬、川辺敏晃、城ヶ原貴通、名倉悟郎、坂本信介、越本知大

九州実験動物雑誌 35 29 - 38 2019年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）

Shinohara A., Nohara M., Kondo Y., Jogahara T., Nagura-Kato G., Izawa M., Koshimoto C.

Experimental Animals 68 ( 4 ) 531 - 539 2019年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Experimental Animals

© 2019 Japanese Association for Laboratory Animal Science. The Asian house shrew, Suncus murinus, is an insectivore (Eulipotyphla, Mammalia) and an important laboratory animal for life-science studies. The gastrointestinal tract of Suncus is simple: the length of the entire intestine is very short relative to body size, the large intestine is quite short, and there are no fermentative chambers such as the forestomach or cecum. These features imply that Suncus has a different nutritional physiology from those of humans and mice, but little is known about whether Suncus utilizes microbial fermentation in the large (LI) or small (SI) intestine. In addition, domestication may affect the gastrointestinal microbial diversity of Suncus. Therefore, we compared the gastrointestinal microbial diversity of Suncus between laboratory and wild Suncus and between the SI and LI (i.e., four groups: Lab-LI, Lab-SI, Wild-LI, and Wild-SI) using bacterial 16S rRNA gene library sequencing analyses with a sub-cloning method. We obtained 759 cloned sequences (176, 174, 195, and 214 from the Lab-LI, Lab-SI, Wild-LI, and Wild-SI samples, respectively), which revealed that the gastrointestinal microbiota of Suncus is rich in Firmicutes (mostly lactic acid bacteria), with few Bacteroidetes. We observed different bacterial communities according to intestinal region in laboratory Suncus, but not in wild Suncus. Furthermore, the gastrointestinal microbial diversity estimates were lower in laboratory Suncus than in wild Suncus. These results imply that Suncus uses lactic acid fermentation in the gut, and that the domestication process altered the gastrointestinal bacterial diversity.

DOI： 10.1538/expanim.19-0021