No abstract available.
Animals ; Hindlimb Suspension* ; Hindlimb*

purpose of this study was to investigate alterations in histochemical properties in the gastrocnemius & soleus muscles of rats following hindlimb suspension for 1 week. A modification of the Morey and Musacchia models was used to determine atrophic responses of rat muscle. The weights of rat's whole body and of gastrocnemius and soleus muscles were affected by suspensions. A reduction of type I distribution was accompanied by an increase in type II fibers. The cross sectional area of all fiber types was reduced after suspension. These results suggest that type I fibers showed greater susceptibility than type II fibers and some amount of type I fibers might have been converted to type II fibers.
Animals ; Hindlimb Suspension* ; Hindlimb* ; Muscles ; Rats* ; Suspensions ; Weights and Measures

No abstract available.
Animals ; Carbohydrate Metabolism* ; Hindlimb Suspension* ; Hindlimb* ; Insulin* ; Muscle, Skeletal* ; Rats* ; Receptor, Insulin*

OBJECTIVETo investigate the changes in the afferent discharge activities of the sensory nerve endings in muscle spindles of rats with hindlimb immobilization.

METHODSPlaster cast was used immobilize the hindllimbs of rats. Using air-gap technique, the spontaneous discharge of the muscle spindles and its responses to perfusion with succinylcholine (0.05 mg/ml) and suspension in an extended position were observed in isolated muscle spindles from rats with hindlimb immobilization for 3, 7, and 14 days.

RESULTSThe muscle spindles of rat soleus showed a sharp decrease in spontaneous discharge frequency (P<0.01) and response to succinylcholine perfusion after 3 days of hindlimb immobilization (P<0.05). Significant changes of the firing rate in an extended position was observed in rats after a 14-day immobilization (P<0.01). The duration of individual spikes was significantly prolonged following hindlimb immobilization (P<0.01).

CONCLUSIONMuscle spindle discharges decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of the muscle spindle.

Animal models of depression are used to study pathophysiology of depression and to advance therapeutic strategies. Stress-induced depression models in rodents are widely used. However, amenable behavioral criteria and experimental procedures that are suitable for animal models have not been established. Given that depression is clinically diagnosed by multiple symptomatic criteria and stress effects are imposed to the brain non-specifically in stress-induced depression models, analyses of depression states in rodents using multiple symptomatic criteria may provide more power than any methods relying on a single symptomatic criterion. To address this, C57BL/6 inbred mice were restrained for 2 h daily for 14 d, and depression states of individual mice were assessed using the U-field test, behavioral assessment developed to measure animal's sociability, and the tail suspension test and/or forced swim test, which are the typical methods that measure psychomotor withdrawal states. Although the majority of these mice showed severe depressive behaviors in both tests, a significant proportion of them, which were all inbred mice and received the same amount of restraints, expressed differential depression states in the sociability test and psychomotor withdrawal tests. To easily read-out differential depression states of individuals in two different tests, a standard method and basic parameters required to construct two-way behavior matrix were introduced. The utility and features of this two-way behavior analysis method for studies of different depressive states of individuals were discussed.
Animals ; Brain ; Depression* ; Hindlimb Suspension ; Mice ; Models, Animal ; Rodentia*

PURPOSE: To compare differences in the biomechanical characteristics of posterior cruciate ligament (PCL) reconstructed by the inlay and transtibial techniques. MATERIALS AND METHODS: PCL reconstruction was performed in 12 pairs of porcine hindlimbs using the inlay and transtibial techniques. Cyclic load testing was carried out in three steps. The first step was 750 cycles at 35-350 N, the second 10,000 cycles at 35-350 N, and the third 10,000 cycles at 45-450 N. Length changes of the reconstructed PCLs were measured and the sites of rupture observed. RESULTS: Among the 10 pairs of limbs that completed the test procedure, the graft ruptured before step 3 in all specimens except one in the transtibial group, and seven specimens completed step 3 testing in the inlay group. Comparing the load elongation curves obtained in step 2 tests, more elongation of the graft was evident in the transtibial group (p<0.05). The site of rupture was proximal 1/3 (2 specimens) or distal 1/3 (1) to the graft in the inlay group, and in the distal 1/3 for all specimens of the transtibial group. CONCLUSION: These results suggest that the tibial tunnel orifice renders a risk of attritional rupture to the graft in the transtibial technique. In this respect, the inlay technique has a biomechanical advantage over the transtibial technique.
Animals ; Extremities ; Hindlimb ; Inlays* ; Posterior Cruciate Ligament* ; Rupture ; Transplants

This study was carried out to investigate the distribution of serotonin-immunoreactive neruons in the raphe nucleus of the ataxic pogo (pogo/pogo) mice derived from a Korean wild mice. Using by immunohistochemistry, we undertook to elucidate any correlation between the serotonin expression and behavior ataxia including abnormal hindlimb extension in the ataxic pogo mice. The present study has two important findings. First, serotonin immunoreactivity was increased in the raphe nucleus of the ataxic pogo mice. Second, serotonin immunoreactivity was different with the region of raphe nucleus. In the dorsal part of dorsal raphe nucleus (DRD), ventrolateral part of dorsal raphe nucleus (DRVL) and median raphe nucleus (MR), serotonin immunoreactivity was increased, whereas the ventral part of dorsal raphe nucleus (DRV) and interfascicular part of dorsal raphe nucleus (DRI) was similar with the control mice. Therefore, elevated expression of the serotonin in the raphe nucleus of ataxic pogo mice might be a source of behavior ataxia and may be related with the induction of the ataxic phenotype including abnormal hindlimb movements.
Animals ; Ataxia ; Hindlimb ; Immunohistochemistry ; Mice* ; Neurons* ; Phenotype ; Raphe Nuclei* ; Serotonin

BACKGROUND: The purpose of this study was to examine histological changes of testes induced by hindlimb unloading & position change of testis in mature adult male rats. METHOD: Eight month old (390~410g) 36 male Sprague-Dawley rats were weight-matched assigned to Ground Control (GC), Hindlimb Unloading (HU), Hindlimb Unloading & Testis Tie(HUT), Intra-abdominal Testis(IAT) for 24 days. Daily body weight was watched for status of animal. Testis weight, Seminiferous Tubule Diameter(STD), Seminiferous Tubule Perimeter(STP), Serminiferous Tubule Area(STA), Sertori Cell Height(SCH) were examined in each group. RESULTS: The 24-day hindlimb unloading of HU, HUT and IAT showed no significant change of body weight compared to GC. HUT maintained the weights, STD, STP, STA, SCH of their testes as GC while HU, IAT had significantly decreased the weights, STD, STP, STA of their testes. CONCLUSION: These results support that hindlimb unloading experiment induces serious morphological changes of testes. Therefore, on the hindlimb unloading experiment, IAT should be avoid or the effect of IAT should be correct. It will be necessary to study the pure effect of hindlimb unloading without IAT on the musculoskeltal system and so on which are associated with testosterone.
Adult ; Animals ; Body Weight ; Hindlimb Suspension* ; Hindlimb* ; Humans ; Male ; Rats* ; Rats, Sprague-Dawley ; Seminiferous Tubules ; Testis* ; Testosterone ; Weightlessness ; Weights and Measures

BACKGROUND: The purpose of this study was to examine site-specific bone strength changes induced by hindlimb unloading in mature adult male rats. METHODS: Eight month old (390-410 g) 26 male Sprague-Dawley rats were weight-mated assigned to either a Ground control (CON) or a Hindlimb Unloading (HU) for 24 days. Daily body weight was watched for status of animal. Weight, BMD, strength, geometry of femur, tibia and humerus were examined in both groups. RESULTS: The 24-day hindlimb unloading of HU showed no significant change of body weight, total bone mineral, and bone geometry compared to CON. HU showed that the upper limb had maintained total bone mineral, bone geometry, and bone mechanical strength compared to CON. The hindlimb of HU had significantly decreased bone strength and ultimate stress (F/B) compared to CON. DEXA analysis of BMD and BMC in HU showed inconsistent changes at femur and tibia, although a relatively constant increase was shown in humerus. In HU rats, mechanical stress testing of compulsive fracture showed that more significant decreases in UL (ultimate load) and ultimate stress (F/B) was seen in femur than in tibia. CONCLUSION: These results support the theory that hindlimb unloading contribute to deleterious effects in femur rather than in tibia. It induced higher loss of mechanical bone strength in femur. In testing for BMD, pQCT, 2D, or 3D is recommended. DEXA is not recommended because it has inconsistent results and limitation with respect to the characteristics of area BMD (g/cm2) as a surrogate of volume BMD (g/cm3).
Adult* ; Animals ; Body Weight ; Femur ; Hindlimb Suspension* ; Hindlimb* ; Humans ; Humerus ; Male* ; Rats* ; Rats, Sprague-Dawley ; Stress, Mechanical ; Tibia ; Upper Extremity ; Weightlessness

BACKGROUND: This study tried to compare the morphological changes of collagen fibrils between disused and denervated old rat Achilles tendons with those of young rats through quantitative analyses of collagen fibril diameters by transmission electron microscopy (TEM). METHODS: Old (18 months old) and young (6 months old) male Sprague-Dawley rats were divided into 3 groups (n=8 in each group): a control group, a complete denervation group for 4 weeks after the transection of the right sciatic nerve, and a disuse group with hindlimb unweighing by tail suspension. Each explanted Achilles tendon was used for TEM observation. Under TEM, quantitative analyses of collagen fibril diameters were performed. RESULTS: All groups comprising old rats had smaller mean diameters and showed more left-shifted distribution of collagen fibril diameters than young rats. In particular, the disuse group of old rats showed a more prominent mean fibril diameter decrease than young rats. CONCLUSION: Disuse might cause a more prominent decrease of collagen fibril size in the old than the young.
Achilles Tendon ; Aged ; Animals ; Collagen ; Denervation ; Fibrillar Collagens ; Hindlimb ; Hindlimb Suspension ; Humans ; Male ; Microscopy, Electron, Transmission ; Rats ; Rats, Sprague-Dawley ; Sciatic Nerve