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

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*

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.

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

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

We studied the effects of simulated microgravity on mouse oocytes maturation, and analyzed whether the tail-suspended model can be applied to investigate simulated microgravity effects on reproductive processes in female mice. Mouse oocytes were cultured in vitro with microgravity simulated by a rotating wall vessel bioreactor and by tail-suspended model, and the maturation rate of the mouse oocytes in the two models were examined in vivo. The maturation rate of mouse oocytes cultured in simulated microgravity was 8.93%, and that was 72.33% in 1g gravity. In ratio, oocyte maturation rate had no significant difference between the rotational group and control group. Microgravity simulated by the tail-suspended model inhibited mouse oocytes maturation and increased the rate of oocytes abnormity. The maturation rate of tail-suspended mouse oocytes was 14.54%, which was significantly lower than that of control group. Tail-suspended model should be an ideal model to investigate simulated microgravity effects on reproductive processes of female mice.
Animals ; Cells, Cultured ; Female ; Hindlimb Suspension ; Mice ; Oocytes ; cytology ; physiology ; Oogenesis ; physiology ; Weightlessness Simulation

The etiology of most psychiatric disorders is still incompletely understood. However, growing evidence suggests that stress is a potent environmental risk factor for depression and anxiety. In rodents, various stress paradigms have been developed, but psychosocial stress paradigms have received more attention than non-social stress paradigms because psychosocial stress is more prevalent in humans. Interestingly, some recent studies suggest that chronic psychosocial stress and social isolation affects mainly anxiety-related behaviors in mice. However, it is unclear whether chronic non-social stress induces both depression- and anxiety-related phenotypes or induces one specific phenotype in mice. In the present study, we examined the behavioral consequences of three chronic non-social stress paradigms: chronic predictable (restraint) stress (CPS), chronic unpredictable stress (CUS), and repeated corticosterone-HBC complex injection (RCI). Each of the three paradigms induced mild to severe depression/despair-like behaviors in mice and resulted in increased immobility in a tail suspension test. However, anxiety-related phenotypes, thigmotaxis and explorative behaviors, were not changed by the three paradigms. These results suggest that depression- and anxiety-related phenotypes can be dissociated in mouse stress models and that social and non-social stressors might affect brain circuits and behaviors differently.
Animals ; Anxiety* ; Brain ; Depression ; Hindlimb Suspension ; Humans ; Mice* ; Phenotype ; Risk Factors ; Rodentia ; Social Isolation

Weight-bearing bone is constantly adapting its structure and function to mechanical environments. Loading through routine exercises stimulates bone formation and prevents bone loss, but unloading through bed rest and cast immobilization as well as exposure to weightlessness during spaceflight reduces its mass and strength. In order to elucidate the mechanism underlying unloading-driven bone adaptation, ground-based in vitro and in vivo analyses have been conducted using rotating cell culturing and hindlimb suspension. Focusing on gene expression studies in osteoblasts and hindlimb suspension studies, this minireview introduces our recent understanding on bone homeostasis under weightlessness in space. Most of the existing data indicate that unloading has the opposite effects to loading through common signaling pathways. However, a question remains as to whether any pathway unique to unloading (and not to loading) may exist.
Adaptation, Physiological ; Animals ; Bone and Bones ; cytology ; physiology ; Hindlimb Suspension ; physiology ; Humans ; Osteoblasts ; physiology ; Weightlessness

Animals ; Antidepressive Agents ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Hindlimb Suspension ; Male ; Medicine, Chinese Traditional ; Mice ; Swimming