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Effects of a lack of Snark on activity, heart rate, and fat and skeletal tissues in mice
Author(s) -
IchinosekiSekine Noriko,
Naito Hisashi,
Tsuchihara Katsuya,
Kakigi Ryo,
Ogura Yuji,
Kurosaka Mitsutoshi,
Katamoto Shizuo,
Esumi Hiroyasu
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1175.12
Subject(s) - medicine , adipose tissue , endocrinology , skeletal muscle , chemistry , white adipose tissue , myofibril , body weight , composition (language) , heart rate , biology , blood pressure , linguistics , philosophy
This study clarified the characteristics of Snark +/− mice in terms of their activity, resting heart rate (HR), and fat and skeletal tissues. Eleven 2‐month‐old male mice ( Snark +/+: n=4, WT; Snark +/−: n=7, KO) were kept individually in stainless cages equipped with a running wheel for 4 months and given standard chow and water ad libitum . After this time, the animals were anesthetized and the hind limb muscles and adipose tissues were collected. Ten‐μm‐thick sections were cut and stained for myofibrillar ATPase at pH 4.3. At the end of the experiment, there was no difference between WT and KO in body weight or food intake. KO mice tended to have a lower HR. Interestingly, the KO mice ran twice as far as the WT mice (1420.7 ± 223.4 vs. 737.6 ± 146.7 km, p <0.01). The weight of brown adipose tissue did not differ, whereas the KO mice had significantly less white adipose tissue (14.0 ± 1.4 vs. 9.4 ± 2.6 mg/g, p <0.001). Soleus muscle weight, number of muscle fibers, and fiber type composition did not differ between WT and KO, while the fiber area in the soleus was significantly smaller in KO mice (2606.7 ± 328.6 vs. 2074.7 ± 160.7 μm 2 p <0.05). Our results suggest that a lack of Snark enhanced activity, and reduced HR and fat deposition, in an environment that allowed mice to exercise. No effect on muscle weight or fiber type composition was found, although fiber area in the soleus muscle was smaller in KO.