Effects of a simulated microgravity model on cell structure and function in rat testis and epididymis

Hadley, Jill A.; Hall, Joseph; O'Brien, Ami; Ball, Richard W.

doi:10.1152/jappl.1992.72.2.748

Cited by 24 publications

(23 citation statements)

References 16 publications

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“…Testicular testosterone levels in the rat are consistently shown to decrease in rats flown into space, as well as in a simulated space environment (16,30). However, the data on the changes of serum testosterone levels are contradictory, involving decreases in testicular weight and testosterone levels and increases in serum luteinizing hormone and follicle-stimulating hormone in 7-day tail-suspended rats (16,48), as well as decreases in thyroxin and testosterone secretion with no changes in serum corticosterone, growth hormone, or prolactin (30).…”

Section: Discussionmentioning

confidence: 97%

“…However, the data on the changes of serum testosterone levels are contradictory, involving decreases in testicular weight and testosterone levels and increases in serum luteinizing hormone and follicle-stimulating hormone in 7-day tail-suspended rats (16,48), as well as decreases in thyroxin and testosterone secretion with no changes in serum corticosterone, growth hormone, or prolactin (30). Other studies have reported a decrease in the testicular testosterone levels but a lack of negative effect on spermatogenesis (2,12).…”

Section: Discussionmentioning

confidence: 99%

“…Because of the increased temperature in this new environment, the testes undergo several changes, including dramatic reduction in spermatogenesis (20). Marked changes occur in the histology of the testis and epididymis in tail-suspended rats without inguinal canal ligation (5,16). Therefore, in the present study after a short period of acclimatization in the animal care facility in both control and tail-suspended rats under anesthesia, a loose ligature of nonabsorbable suture was placed around the inguinal canal to prevent the testes from moving into the abdominal cavity.…”

Section: Protocolmentioning

confidence: 99%

“…On day 12, the rats were removed from suspension, anesthetized, and subjected to MRI (16). Proton MRI was performed by using a 4.7-T 33-cm-bore magnet (SISCO/Varian, Palo Alto, CA).…”

Section: Mri Of Muscle and Bonementioning

confidence: 99%

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Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI

Wimalawansa¹,

Chapa²,

Wei

et al. 1999

Journal of Applied Physiology

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J. Wimalawansa. Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI. J. Appl. Physiol. 86(6): 1841-1846, 1999.-Microgravity causes rapid decrement in musculoskeletal mass is associated with a marked decrease in circulatory testosterone levels, as we reported in hindlimb-suspended (HLS) rats. In this model which simulates microgravity, we hypothesized that testosterone supplementation should prevent these losses, and we tested this in two studies. Muscle volumes and bone masses were quantitated by using magnetic resonance imaging (MRI) on day 12. In the first study, 12-wk-old Sprague-Dawley rats that were HLS for 12 days lost 28.5% of muscle volume (53.3 Ϯ 4.8 vs. 74.5 Ϯ 3.6 cm 3 in the ground control rats; P Ͻ 0.001) and had a 5% decrease in bone mineral density (BMD) (P Ͻ 0.05). In the second study, 30 male 12-wk-old Wistar rats were HLS and were administered either a vehicle (control), testosterone, or nandrolone decanoate (ND). An additional 20 rats were used as ground controls, one-half of which received testosterone. HLS rats had a significant reduction in muscle volume (42.9 Ϯ 3.0 vs. 56 Ϯ 1.8 cm 3 in ground control rats; P Ͻ 0.01). Both testosterone and ND treatments prevented this muscle loss (51.5 Ϯ 2 and 51.6 Ϯ 1.2 cm 3 , respectively; a 63% improvement; P Ͻ 0.05). There were no statistical differences between the two active treatment groups nor with the ground controls. Similarly, there was an 85% improvement in BMD in the testosterone group (1.15 Ϯ 0.04 vs. 1.04 Ϯ 0.04 density units in vehicle controls; P Ͻ 0.05) and a 76% improvement in the ND group (1.13 Ϯ 0.07 density units), whereas ground control rats had a BMD of 1.17 Ϯ 0.03 density units. Because serum testosterone levels are markedly reduced in this model of simulated microgravity, androgen replacement seems to be a rational countermeasure to prevent microgravity-induced musculoskeletal losses. osteoporosis; microgravity; bone turnover; bone mineral density; anabolic steriod; disuse atrophy DECREMENTS IN BONE AND MUSCLE mass are major concerns in extended space missions (1,8,9,38,49). Immobilization (e.g., bed rest or restricted movements of limbs) can also cause rapid losses in muscle or bone mass (6,9,25,26). Immobilization, prolonged bed rest, and spaceflight conditions inducing microgravity conditions can lead to the general or selective loss of muscle volume and mass. In addition, these conditions lead to negative calcium balance and loss of bone mineral density (BMD) (11,13,32,33). A similar reduction in musculoskeletal mass has been reported due to the immobilization of extremities seen in external bandaging, casting, or neural resectioning (13,25,27,(39)(40)(41)(42)(43). Both mineralization and collagen metabolism seem to be impaired in animals during the first few days of spaceflight (34). Urine analysis in Skylab astronauts has shown a significant loss of minerals, including calcium (10, 37). Reduction of muscle forces leads to a decrease in bone formation and BMD in the os calcis and an i...

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Protocolmentioning

confidence: 99%

“…On day 12, the rats were removed from suspension, anesthetized, and subjected to MRI (16). Proton MRI was performed by using a 4.7-T 33-cm-bore magnet (SISCO/Varian, Palo Alto, CA).…”

Section: Mri Of Muscle and Bonementioning

confidence: 99%

See 2 more Smart Citations

Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI

Wimalawansa¹,

Chapa²,

Wei

et al. 1999

Journal of Applied Physiology

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“…Many studies have provided evidence that HS aects the structural, functional, and biochemical properties of skeletal muscles, especially postural muscles such as the soleus (SOL; Desplanches et al 1990; Thomason and Booth 1990;Oishi et al 1994). Moreover, signi®cant changes have been observed in morphometric parameters such as the decrease of organ mass, reduction of adipose tissue, and also in speci®c endocrine parameters such as alterations of plasma testosterone concentrations (Grindeland et al 1990;Hadley et al 1992;Taillandier et al 1993;Royland et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Effects of hindlimb suspension and androgen treatment on testosterone receptors in rat skeletal muscles

Bricout

Serrurier²,

Bigard³

et al. 1999

European Journal of Applied Physiology

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This study tested the specific and combined effects of testosterone treatment and hindlimb suspension (HS) on the properties of steroid receptors in skeletal muscle. Male rats were either administered weekly high doses of testosterone heptylate (10 mg x kg(-1)) or olive oil placebo, and were either tail-suspended or acted as controls. After 3 weeks of treatment, three muscles were excised from each animal, soleus (SOL), extensor digitorum longus (EDL), and plantaris. The results showed that the testosterone treatment was unable to minimise the HS-induced atrophy of skeletal muscle. As expected, HS altered the fibre-type composition of SOL muscles (-33% of type I, +188% and +161% of type IIa and intermediate fibres respectively, P < 0.01). No overall effect of treatment was detected on the fibre-type composition of either slow or fast-twitch muscles. Binding capacity determined by a radiocompetition technique was increased by HS, especially in SOL and EDL muscles (P < 0.01), while HS or steroid treatment decreased the affinity of the steroid receptors. The combination of HS and testosterone administration resulted in a decrease in binding capacity and affinity of steroid receptors in skeletal muscles. Steroid receptors in fast-twitch muscles exhibited a higher affinity than those in slow-twitch muscles, and it is suggested that it is likely that testosterone treatment is more effective in fast-twitch than in slow-twitch muscles. It was concluded that the lack of preventive effect of testosterone treatment on HS-induced SOL muscle atrophy could be explained by both a decrease in steroid sensitivity and the removal of mechanical factors.

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Effects of Caudal Elevation on Testicular Function in Rats Separation of Effects on Spermatogenesis and Steroidogenesis

DEAVER,

AMANN,

HAMMERSTEDT

et al. 1992

Journal of Andrology

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A variety of biologic processes are perturbed when exposed to microgravity (space flight) for more than 7 days, including testicular function. Suspension of rats in a special harness (caudal elevation) to induce thoracic pooling of blood fluids and remove the support function of the hind limbs is used to mimic, on earth, the effects of microgravity encountered during space flight. Typically, this induces cryptorchidism in male rats. Three experiments were conducted to differentiate the effects of caudal elevation (30° angle) and anatomic location of testes on spermatogenesis and steroidogenesis. Rats were subjected to caudal elevation for 7 days using either a tail harness (experiments 1 and 2) or a whole‐body harness (experiment 3). Testes of rats fell into the abdominal cavity when a tail harness was used, but ligation of the inguinal canal prevented this repositioning. For rats with abdominal testes, testicular weight was reduced (P < 0.05) and histology of testes was abnormal; the number of spermatids per gram parenchyma was lower (P < 0.05) in tail‐suspended rats compared with control rats. In contrast, spermatogenesis was not affected by caudal elevation in most rats in which the inguinal canal was ligated or in rats elevated by whole‐body harness. Concentrations of testosterone in serum and testicular interstitial fluid were lower (P < 0.05) in suspended rats, regardless of the method used for caudal elevation or anatomic location of testes. Concentrations of luteinizing hormone in serum were elevated (P < 0.05) in rats with intra‐abdominal testes. The authors conclude that caudal elevation of rats using either a whole‐body harness or a tail harness after ligation of the inguinal canal results in altered steroidogenesis but normal spermatogenesis. Because this is similar to what occurs in the testes of male rats exposed to space flight, caudal elevation can be a useful model system to study the mechanisms responsible for reduced testosterone secretion during exposure to microgravity.

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Effects of a simulated microgravity model on cell structure and function in rat testis and epididymis

Cited by 24 publications

References 16 publications

Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI

Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI

Effects of hindlimb suspension and androgen treatment on testosterone receptors in rat skeletal muscles

Effects of Caudal Elevation on Testicular Function in Rats Separation of Effects on Spermatogenesis and Steroidogenesis

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