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Biomedical subjects

K Osawa

Publications and source records attributed to K Osawa.

At least 55 records · Page 3Linked to original sources
PubMed1988

Postnatal development of the mouse temporal muscle and effects of a fine-grained diet on the muscle spindle.

The postnatal development of the mouse temporal muscle and effects of a fine-grained diet on muscle spindles were investigated. On d 25 after birth, 3 types of extrafusal muscle fibers could be distinguished on the basis of SDH activity, but not on the basis of their diameters. And in 50-d-old mice, 3 types of the muscle fibers had different diameters each other. In intrafusal muscle fibers, the postnatal changes of the SDH activity were similar to those of extrafusal muscle fibers, but the diameter distribution showed unimodal statistical distribution from 10th to 50th postnatal day. On the other hand, in control 180-d-old mice, 80 percent of muscle spindles in the temporal muscle had complete annulospiral endings, but the ratio of muscle spindles with complete annulospiral endings was decreased significantly in mice fed a fine-grained diet. The diet also decreased the diameter of the endings significantly. These results suggest that the main changes in the morphological and functional properties of the mouse temporal muscle occur in during and early after weaning period, and that normal mastication is needed to maintain the homeostatic condition of the mouse temporal muscle.

Animals↗
PubMed1987

Effects of long-term intake of a fine-grained diet on the mouse masseter muscle.

Muscle fibers of the masseter muscle of mice which had been fed a fine-grained diet for various periods were studied histochemically and morphometrically. The diameters of both extrafusal and intrafusal muscle fibers decreased with time in mice fed a fine-grained diet, compared with those of control mice. In animals maintained on the special diet for 160 days after weaning at the 20th postnatal day, the effects of the diet on the diameter of muscle spindles were severe, and the diameter of each type of red and white fibers was significantly smaller than those of control animals. But a significant difference was not recognized in the diameter of intermediate fibers between control and treated mice. Unexpectedly, white fibers having a smaller diameter than red fibers were observed in diet-fed mice after the 180th postnatal day, although white fibers having such small diameter were not detectable in control animals. Succinic dehydrogenase activities were decreased in both extrafusal and intrafusal fibers of experimental animals. Moreover, muscle spindles with no annulospiral endings were increased in number in mice fed the diet for 130 and 160 days after weaning, although those spindles also increased in control animals. The diameters of outer capsules and primary endings were also significantly decreased in the animals kept on the diet for a long time. These effects of the fine-grained diet on the mouse masseter muscle became severer with time.

Adaptation, Physiological↗
PubMed1987

[Effects of capsaicin on spontaneous unit discharges in amygdala single neurons of cats].

Effects of capsaicin on spontaneous unit discharges in the amygdala single neurons were studied in 26 gallamine immobilized adult cats. Single units were recorded from the amygdala using a stainless steel microelectrode. Of 63 amygdala neurons, 34 were responsive to both noxious (pinching the skin with toothed forceps) and innoxious (tap and/or hair bending) stimuli, 11 were responsive to only innoxious stimuli and the others did not respond to these stimuli. Of 34 neurons responsive to both noxious and innoxious stimuli, 20 were responsive to both bradykinin and capsaicin, and 7 were responsive to only capsaicin. All neurons responsive to bradykinin were also responsive to capsaicin. All neurons responsive to only innoxious stimuli responded to neither bradykinin nor capsaicin. The latency for bradykinin and capsaicin was 8.05 +/- 0.92 sec and 1.21 +/- 0.33 sec, respectively. The duration for bradykinin and capsaicin was 14.72 +/- 1.78 sec and 26.22 +/- 4.16 sec, respectively. The increase in firing frequency produced by capsaicin was depressed by morphine (1 mg/kg, i.v.). These depressant effects of morphine on the amygdala neurons were antagonized by naloxone (0.2 mg/kg, i.v.).

Action Potentials↗
PubMed1985

Postnatal development of the anulospiral endings of Ia fibers in muscle spindles of mice.

The formation of the anulospiral ending of Ia fibers in muscle spindles was investigated in the masseter muscle of developing mice. Before 15 days after birth, the complete anulospiral ending was not observed in almost all of the muscle spindles examined. With the growth of mice, the Ia fiber began to construct the spiral ending, and by the 40th postnatal day after weaning, almost all of the Ia fibers of the muscle spindles had complete coiled endings, though the formation still continued in some spindles. The continuous formation of anulospiral endings for a long period after weaning indicates that muscle spindle morphogenesis may be affected by muscle tension in the masseter muscle due to the movement activated after weaning.

Animals↗