Osteoarthritis is a degenerative change in the joint that causes damage to the articular cartilage, resulting in overexpression of inflammatory cytokine in the damaged chondrocytes, which leads to damage to the articular cartilage and is completely treated with antibiotics. We recovered the damage to the articular cartilage caused by osteoarthritis and investigated the effect of a low-molecular-weight collagen-based functional material without side effects. In this study, we investigated the ameliorative effects of YB in a monosodium idoacetate(MIA)-induced osteoarthritis rats. The experimental groups were divided with 5groups (n = 12) of SD rat: normal control(NC), MIA, MIA+L. plantarum (3×1011 CFU/ml), MIA+collagen and MIA+YB-21. Histological examinations indicated that YB-21 cartilage structure change, cartilage cell damage, and the loss of proteoglycan induced by MIA. Moreover, YB-21 reduced serum level expressions of, tumor necrosis factor-α(TNF-α), Interleukin6(IL-6), Interleukin1β(IL-1 β), Matrix metalloproteinase-9(MMP-9), Tissue inhibitor of metalloproteinases-1(TIMP-1). These results suggest that YB has a positive effect on osteoarthritis by restoring joint cartilage and anti-inflammatory effects due to the reaction of osteoarthritis in the MIA-induced rat.
This study evaluates the gastroprotective effect of cabbage extract with sulforaphane content of 5.19 mg/L and Smethylmethionine content of 469.28 μg/L. In vitro, the lipopolysaccharide (LPS)-treated group had an increased NO activity compared to the normal group, and the concentration of NO was reduced when the cabbage extract was treated in the dose manner. The level of IL-6 induced by LPS was dose-dependently reduced when the extract was treated. The cabbage extract concentration was orally administered in rats at 5.75 mg/kg, 11.5 mg/kg, and 23 mg/ kg, and the inhibitory effect on gastric damage by HCl-ethanol was observed. Histological analysis exhibited mucosal erosion in the gastritis model compared to the normal group, while the ameliorating effect of the generated erosion was observed in the cabbage-treated group. The histamine concentration was significantly increased in the gastritis-induced animal model, and the histamine concentration was decreased in the 23 mg/L-treated group of cabbage extract. In conclusion, the results of this study suggest that cabbage extract not only down-regulates cytokines in vitro, but is also directly involved in histamine secretion in an animal model of gastritis; therefore, cabbage extract can help inhibit gastrointestinal disorders by improving the protective barrier.
Mutations in the luteinizing hormone/chorionic gonadotropin receptors (LH/CGRs), representatives of the G protein-coupled receptor family, have been rapidly identified over the last 20 years. This review aims to compare and analyze the data reported the activating and inactivating mutations of the LH/CGRs between human, rat, equine and fish, specifically (Japanese eel Anguilla japonica). Insights obtained through detailed study of these naturally-occurring mutations provide a further update of structure-function relationship of these receptors. Specifically, we present a variety of data on eel LH/CGR. These results provide important information about LH/CGR function in fish and the regulation of mutations of the highly conserved amino acids in glycoprotein hormone receptors.
Activation of transient receptor potential vanilloid 1 (TRPV1), a calcium permeable channel expressed in primary sensory neurons, induces the release of glutamate from their central and peripheral afferents during normal acute and pathological pain. However, little information is available regarding the glutamate release mechanism associated with TRPV1 activation in primary sensory neurons. To address this issue, we investigated the expression of vesicular glutamate transporter (VGLUT) in TRPV1-immunopositive (+) neurons in the rat trigeminal ganglion (TG) under normal and complete Freund’s adjuvant (CFA)-induced inflammatory pain conditions using behavioral testing as well as double immunofluorescence staining with antisera against TRPV1 and VGLUT1 or VGLUT2. TRPV1 was primarily expressed in small and medium-sized TG neurons. TRPV1+ neurons constituted approximately 27% of all TG neurons. Among all TRPV1+ neurons, the proportion of TRPV1+ neurons coexpressing VGLUT1 (VGLUT1+/ TRPV1+ neurons) and VGLUT2 (VGLUT2+/TRPV1+ neurons) was 0.4% ± 0.2% and 22.4% ± 2.8%, respectively. The proportion of TRPV1+ and VGLUT2+ neurons was higher in the CFA group than in the control group (TRPV1+ neurons: 31.5% ± 2.5% vs. 26.5% ± 1.2%, VGLUT2+ neurons: 31.8% ± 1.1% vs. 24.6% ± 1.5%, p < 0.05), whereas the proportion of VGLUT1+, VGLUT1+/TRPV1+, and VGLUT2+/TRPV1+ neurons did not differ significantly between the CFA and control groups. These findings together suggest that VGLUT2, a major isoform of VGLUTs, is involved in TRPV1 activation-associated glutamate release during normal acute and inflammatory pain.
Under the stressed condition, a complex feedback mechanism for stress is activated to maintain homeostasis of the body and secretes several stress hormones. But these stress hormones impair synthesis and secretion of the reproductive hormones, followed by suppression of ovarian function. Cytochrome P450 1A2 (CYP1A2) plays a major role in metabolizing exogenous substances and endogenous hormones, and its expression is recently identified at not only the liver but also several organs with respect to the pancreas, lung and ovary. Although the expression of CYP1A2 can be also affected by several factors, understanding for the changed pattern of the ovarian CYP1A2 expression upon stress induction is still limited. Therefore, CYP1A2 expression in the ovaries from immobilization stress-induced rats were assessed in the present study. The stress-induced rats in the present study exhibited the physiological changes in terms of increased stress hormone level and decreased body weight gains. Under immunohistological observation, the ovarian CYP1A2 expression in both control and the stressed ovary was localized in the antral to pre-ovulatory follicles. However, its expression level was significantly (p < 0.01) higher in the stress-induced group than control group. In addition, stress-induced group presented more abundant CYP1A2-positive follicles (%) than control group. Since expression of the ovarian CYP1A2 was highly related with follicle atresia, increased expression of CYP1A2 in the stressed ovary might be associated with changes of the ovarian follicular dynamics due to stress induction. We hope that these findings have important implications in the fields of the reproductive biology.
Cytochrome P450 1A2 (CYP1A2) is a member of the cytochrome P450 superfamily enzymes in mammals and plays a major role in metabolizing endogenous hormones in the liver. In recent days, CYP1A2 expression has been found in not only the liver but also other tissues including the pancreas and lung. However, little information is available regarding the expression of CYP1A2 in the ovary, in spite of the facts that the ovarian follicle growth and atresia are tightly associated with controls of endocrine hormonal networks. Therefore, the expression of CYP1A2 in the ovaries of prepubertal and pubertal rats was investigated to assess its expression pattern and puberty-related alteration. It was demonstrated that the expression level of CYP1A2 was significantly (p < 0.01) higher in the pubertal ovaries than prepubertal counterparts. At the ovarian follicle level in both groups, whereas CYP1A2 expression was less detectable in the primordial, primary and secondary follicles, the strongly positive expression of CYP1A2 was localized in the granulosa cell layers in the antral and pre-ovulatory follicles. However, the ratio of CYP1A2-positive ovarian follicle was significantly (p < 0.01) higher in the ovary of pubertal group (73.1 ± 3.1%) than prepubertal one (41.0 ± 10.5%). During the Immunofluorescence, expression of CYP1A2 was mainly localized in Fas-positive follicles, indicating the atretic follicles. In conclusion, these results suggested that CYP1A2 expression was mainly localized at the atretic follicular cells and affected by the onset of puberty. Further study is still necessary but we hypothesize that CYP1A2 expresses in the atretic follicles to metabolize residue of the reproductive hormones. These findings may have important implications for the fields of reproductive biology of animals.
Glial cells, including astrocytes and microglia, interact closely with neurons and modulate pain transmission, particularly under pathological conditions. In this study, we examined the excitability of substantia gelatinosa (SG) neurons of the spinal dorsal horn using a patch clamp recording to investigate the roles of microglial activation in the nociceptive processes of rats. We used xanthine/xanthine oxidase (X/XO), a generator of superoxide anion (O2∙–), to induce a pathological pain condition. X/XO treatment induced an inward current and membrane depolarization. The inward current was significantly inhibited by minocycline, a microglial inhibitor, and fluorocitrate, an astrocyte inhibitor. To examine whether toll-like receptor 4 (TLR4) in microglia was involved in the inward current, we used lipopolysaccharide (LPS), a highly specific TLR4 agonist. The LPS induced inward current, which was decreased by pretreatment with Tak-242, a TLR4-specific inhibitor, and phenyl N-t-butylnitrone, a reactive oxygen species scavenger. The X/XO-induced inward current was also inhibited by pretreatment with Tak-242. These results indicate that the X/XO-induced inward current of SG neurons occurs through activation of TLR4 in microglial cells, suggesting that neuroglial cells modulate the nociceptive process through central sensitization.
Excessive intake of sodium caused by high salt diet promotes the expression of inflammatory cytokines and differentiation of helper T cells resulting in inflammatory responses. High-glucose diet also contributes to the pathogenesis of periodontitis by inducing changes in the oral microbiome and reducing salivation. However, the effect of a high-salt and glucose diet (HSGD) on the prognosis of periodontitis remains unclear. In this study, a rat model of experimental periodontitis was established by periodic insertion of absorbable sutures containing Porphyromonas gingivalis and Fusobacterium nucleatum strains into the right gingival sulcus to analyze the effect of HSGD on the incidence and progression of periodontitis. The alveolar bone heights (ABH) was measured with microcomputed tomography imaging of the HSGD- and general diet (GD)-treated groups. The right ABH was significantly decreased compared to the left in both groups at 4 weeks after induction of inflammation; however, no significant difference was noted between the groups. Notably, the ABH in the HSGD-treated group was significantly decreased at 8 weeks after induction of inflammation, whereas in the GD-treated group, an increase in the ABH was observed; a significant difference of the ABH was noted between the two groups (p < 0.05). At 12 weeks, recovery of the alveolar bone was observed in both groups, with no significant differences in ABH between the two groups. These findings indicate that the intake of excessive sodium attenuates the recovery rate of the alveolar bone even after the local infectant is removed. In addition, this study demonstrates the use of HSGD in establishing a new animal model of periodontitis.
본 연구는 MIA로 퇴행성관절염을 유도한 랫드에 방사선 형질전환 차조기가 골 대사 및 염증 반응에 미치는 효과를 평가하였다. 방사선 형질전환 차조기를 2주 동안 25, 50, 100 ㎎/㎏/day의 용량으로 경구 투여하고 랫드의 우측 관절 내 공간에 MIA를 주입하였다. 이후 동일한 용량을 4주 동안 지속 투여하였다. 혈청 바이오마커와 무릎 관절 분석의 형태학 및 조직병리학적 분석에 기초한 치료 효과를 평가하였다. 대조군 랫드와 비교하였을 때 방사선 형질전환 차조기는 혈청 내 염증 및 골 대사 마커(COX-2, LTB4, MMP-3, COMP)의 생성량을 유의하게 감소시켰다. 이와는 다르게 TIMP-1 및 calcitonin의 생성이 크게 증가하였다. 또한, 방사선 형질전환 차조기는 무릎 연골과 활막을 효과적으로 보존하였다. 그 결과, 방사선 형질전환 차조기는 퇴행성관절염 증상을 예방하고 완화였다. 따라서, 방사선 형질전환 차조기는 퇴행성관절염 관리를 위한 식·의약품 소재로 사용될 수 있다.
Cognitive impairment is considered to be key research topics in the field of neurodegenerative diseases and in understanding of learning and memory. In the present study, we investigated neuroprotective effects of Schisandra chinensis (SC) and Ribes fasciculatum (RF) extracts in hydrogen peroxide-induced neuronal cell death in vitro and scopolamine-induced cognitive impairment in Sprague Dawley® (SD) rat in vivo. Apoptotic cell death in neuroblastic PC12 cell line was induced by hydrogen peroxide for 1 hour at 100 μM. However, mixture of SC and RF treatment prevented peroxide induced PC12 cell death with no neurotoxic effects. For in vivo experiment, the effect of SC and RF extracts on scopolamine-induced cognitive impairment in SD rat was evaluated by spontaneous alternation behavior in Y-Maze test. After 30 min scopolamine injection, the scopolamine-induced rats presented significantly decreased % spontaneous alteration and acetylcholine level, compared to non-induced group. However, treatment of SC+RF extracts rescued the reduced % spontaneous alteration with acetylcholine concentration from hippocampus in scopolamineinduced rats. These results suggested that mixture of SC and RF extract may be a potential natural therapeutic agent for the prevention of cognitive impairment.
Artemisia annua (AA) is a well-known as a source of antimalarial drug (artemisinin), which also has been traditionally used as an antipyretic and hemostatic agent in Korea and China. In preclinical effective study, a water extract of Artemisia annua (WEAA) ameliorated weight gain and hepatic lipid accumulation in high-fat diet-fed mice. The plasma levels of triglyceride, AST, and ALT were reduced in the WEAA-treated group. Based on these results, the safety of WEAA as a functional ingredient for liver health was evaluated in this repeated dose oral toxicity study before the clinical trial. Sprague- Dawley (SD) rats were treated by gavage with 20 times (1,000 mg/kg) more than the effective dose for 13 weeks. All rats had survived at the end of the study, and there were no changes indicating obviously abnormal clinical sign and behavior. The treatment of WEAA were also observed no obvious toxicities in the body weights, urine, hematological, serum biochemical, ophthalmic and histopathological examinations. Based on the results of this study, the NOAEL (no-observed-adverse-effect level) of WEAA in SD rats was estimated to be 1,000 mg/kg. In conclusion, WEAA could be used as a safe functional ingredient for the improvement of liver health in individuals with hepatic diseases including nonalcoholic steatohepatitis.
Dawley 계 숫컷 흰쥐(200∼210g)를 정상군, CCl4-대조군, CCl4-실험군으로 나누어 실험군은 애엽 에탄올 추출물을 1,000mg/kg,b.w의 용량으로 1일1회7일간 경구 투여 후 사염화탄소를 0.6mg/kg,b.w의 용량으로 복강내 주사 후 다음날 개복하여 혈청내의 Alanine aminotransferase(ALT), Aspartate aminotransferase(AST),Alkaline phosphatase(ALP), Glutamyltranspeptidase(γ-GT), Lactate dehydrogenase(LDH)의 활성도와 중성지방, 콜레스테롤 함량을 측정한 결과 애엽 추출물 투여군에서 CCl4-대조군과 비교하여 유의적인 감소를 나타내었으며, HDL-콜레스테롤은 유의적인 증가를 나타내었다. 간조직중의 지질과산화 함량은 감소를 glutathione함량은 유의적인 증가를 나타내었다 이 실험 결과 애엽 에탄올 추출물은 사염화탄소 투여에 의한 간 손상을 억제하는 보호물질을 함유하고 있음을 알 수 있었다.
정신분열은 대표적인 신경정신성 질환으로 정신분열 환자들은 정신적, 감정적 및 행동적인 장애로 인해 고통받고 있다. 이 연구는 흰쥐를 대상으로 정신분열을 유도함으로써 골격근 조직에서 반응하는 혈관생성 관련 단백질의 변화를 살펴보고 규칙적인 운동의 효과를 알아보고자 수행되었다. 연구의 목적을 위해 흰쥐(SD rats) 총 18마리를 통제(n=6), 정신분열(n=6), 정신분열+운동(n=6) 집단으로 구분하였다. 정신분열 및 정신분열+운동 집단은 총 2주 동안 MK-801처치를 통해 정신분열을 유도하였으며, 정신분열+운동 집단은 4주간 규칙적인 유산소성 운동을 수행하였다. 유산소성 운동은 실험동물용 트레드밀을 이용하여 수행되었으며 HIF-1α 및 VEGF 단백질은 western blot을 통해 관찰하였다. 연구결과, HIF-1α 단백질은 집단간 차이를 보이지 않았다(p>.05). VEGF 단백질의 경우, 통제집단보다 정신 분열 집단에서 유의하게 낮게 나타났으며(p<.01), 정신분열+운동 집단의 VEGF가 정신분열 집단보다 유의하게 높게 나타났다(p<.01). 따라서 골격근 내 혈관생성 관련 단백질들은 정신분열 유도에 의해 낮아질 수 있으며 반대로 운동은 이를 개선하는 효과를 가지는 것으로 사료된다.
본 연구는 렛트(rat)에 있어서 정액 보존액이 인공수정 후 수태율에 미치는 영향을 조사하였다. 시험에 공시한 렛트는 20 주령 이상의 성숙 완료된 암컷 18 마리, 수컷 6 마리였다. 렛트의 정액채취는 먼저 에테르로 흡입 마취시킨 후 양측 정소의 중앙부를 1~2cm 절개하여 정소상체의 미부를 적출한 후 PBS 용액이 담긴 배양접시(⌀35mm)에 옮겨서 수술용 미세 칼로 세절하여 정자를 채취하였다. 각 2 개체로부터 채취된 정액은 활력을 평가한 후 60% 이상의 개체의 정액을 혼합하여 Androhep, Modena 및 BTS 희석액으로 각각 희석하여 정자 농도를 1.5x108spermatozoa/ml 로 조정하였다. 보존액별 혼합된 정액은 17℃에서 6 시간 보관 후 인공수정에 사용하였다. 인공 수정할 암컷 렛트는 실리콘 탭형 progesterone(4-Pregnene-3,20-dione, Sigma) 방출 장치를 질 내에 6 일간 삽입시킨 다음 제거 직후 PMSG 25IU 를 근육주사하고 24 시간 후에 hCG 20IU 를 근육 주사하여 발정과 배란을 유도하였다. hCG 주사 후 6 시간 후에 정액을 주입하여 인공수정시켰다. 처리별 인공수정 직전의 정자 활력은 각각 80%, 60% 및 50% 수준이었다. 정액 주입 직전 미니 스포이드 내 생리식염수로 질 내 상피세포를 관류 흡입 한 후 슬라이드글라스에 도말시켜 표본을 제작하였다. 제작된 표본에서 유핵의 세포상(파편모양)을 관찰하여 정액 주입 시의 발정상태를 확인하였다. 상피세포의 용이한 관찰을 위해 10% giemsa 용액에 도말된 슬라이드글라스를 30 분간 침전하여 염색시킨 후 꺼내어 증류수로 세척하고 드라이기로 건조시킨 후 검경하였다. 인공수정으로 보존액별 정액을 처리별 6 마리의 암컷에게 마리당 0.2ml 의 정액을 주입하였다. 정액주입기는 1ml 주사기에 라운딩된 주사침을 연결한 주사기였다.
인공수정 후 10 일경에 복부촉진법으로 임신 여부를 진단한 결과 수태율은 Androhep, Modena 및 BTS 보존액별 수태율은 각각 83.3%, 66.7% 및 33.3%였다. 하였다. 인공수정 시 그룹별 발정발현율은 각각 83.3%(5/6), 100.0%(6/6) 및 66.7%(4/6)였다. 발정 발현된 개체에 대한 수태율은 Androhep, Modena 및 BTS 보존액의 수태율은 80.0%(4/5), 80.0(4/5)% 및 75.0%(3/4)였다.
이상의 결과에서 정액보존액에 따른 인공수정 후 수태율은 BTS 보존액이 낮게 나타났으나 Androhep 과 Modena 는 차이가 없었다. 또한 발정이 발현된 경우에는 인공수정으로도 거의 수태 된 것으로 나타났으므로 자연교배에 따른 인력과 시간낭비를 줄일 수 있을 것으로 사료되었다.
생체 유래 동해보호제인 난황 및 우유는 세균 및 바이러스에 의한 오염과 감염으로 동결융해 후 정액 성상(보존성)에 부정적 요소로 작용하여 왔다. 이에 본 연구는 렛트(rat)에 있어서 동결보존액이 융해 후 정액 성상에 미치는 영향을 조사하였다. 공시된 렛트는 18 주령 이상의 성숙된 수컷 6 마리였다. 정액채취는 렛트를 먼저 할로탄 흡입마취한 후 양측 정소의 중앙부를 1~2cm 절개하여 정소상체의 미부를 적출한 후 Androhep 희석액이 담긴 배양접시(⌀35mm)에 옮겨서 세절하여 정자를 채취하였다. 정액의 동결과정은 이장희(1993)의 방법에 준하여 실시하였다. 동결보존액으로는 기본적으로 Androhep 희석액을 사용하였으며, 동결보존액이 융해 후 정액 성상에 미치는 영향을 조사하기 위하여 2 개체의 정액을 혼합하여 난황, 두유 및 코코넛 밀크가 각각 20%씩 포함된 1 차 동결보존액으로 1 차 희석 후 정자 농도를 4x107spermatozoa/ml 로 조정하였으며 1 시간에 걸쳐 4℃까지 냉각시켰다. 냉각된 정액은 1 시간에 걸쳐 8%의 glycerol 이 포함된 2 차 동결보존액의 10%, 20%, 30%, 및 40%씩 점등하여 1:1 로 희석시켰다. 최종 희석된 정액은 별도의 glycerol 평형 시간 없이 0.5ml straw 에 충진 시켜 포장하였다. 최종 포장된 정액은 액체질소 표면 5cm 위에서 10 분간 정치시켜 예비 동결시킨 후 침지하여 동결시켰다. 동결과정 중 정자의 활력은 현미경 상의 혈구계산판을 이용하여 100 분율로 평가하였다.
2 개체로부터 채취하여 합쳐진 정액에 대해서 동결보존액의 주요 조성분인 난황, 두유 및 코코넛 밀크에 따른 동결융해 후 정자 활력은 각각 10%, 0% 및 0%로 난황이 다소 높게 나타났다. 이들 주요 조성분의 오염도 수준은 난황, 두유 및 코코넛 순으로 나타났다. 동결과정 중 활력 변화는 채취 직후 합친 상태의 활력은 평균 75% 였으며 냉각 후 2 차 희석이 완료되었을 때에는 40%, 예비동결 후에는 20% 수준, 동결 후 1 일 경과 후의 융해 후 정자 활력은 매우 저조하였다.
이상의 결과에서 동해보호제로서 식물성 동해보호제로써 두유와 코코넛 밀크의 이용 가능성이 없는 것으로 나타났다. 다만 동결 처리 과정 중 정자 활력의 급격한 손실은 정소상체 미부 정자의 미성숙 상태에 의한 내동성 부족으로 사료되었다.
Rats are an important laboratory animal for biomedical research. Though rats have some physiology and genetic similarities to human, several technical issues such as delicate in vitro culture system and low survival rate after pronuclear microinjection have hindered the development of transgenic rat generation. Accordingly, in this study, to produce transgenic rat, we established transposon-mediated insertional mutagenesis by cytoplasmic microinjection. The sleeping beauty transposon (SB) and SB-transposase recognize the precise genome integration into a TA nucleotide by ‘cut-and-paste’ mechanism. It mediates stable integration and reliable long-term expression. DNA, 0.4ng/ul SB vector (IR/DR-EF1a-eGFP-2A-IL2-pA-IR/DR) and mRNA, 5ng/ul SB-transposase were injected to 1-cell stage embryo and one transgenic rat was generated after full-term gestation. To confirm the genome insertion, GFP was detected by PCR. Further, this method was applied to generate transgenic rats producing Cas9 protein. DNA, 0.4ng/ul SB vector (IR/DR-CAG-Cas9-2A-eGFP-pA-IR/DR) and mRNA, 5ng/ul SB-transposase were injected to 1-cell stage embryo. Some of the in vitro cultured embryos showed GFP positive at blastocyst stage and Cas9 sequence was detected by PCR. One stillbirth pup was born to date and genome PCR on Cas9 was positive. In summary, the SB transposon system could be a highly effective method that contribute to the production of transgenic rats. If the protocols will be optimized, we successfully generated efficiently transgenic rats for human models by SB system.
This work was supported by BK21 PLUS Program for Creative Veterinary Science, the National Research Foundation of Korea (2017R1A2B3004972) and the Technology Development Program (S2566872) by MSS.
This study was conducted to investigate the effect of chronic alcohol supplementation on muscle atrophy in growing rats. Eighteen male Sprague Dawley rats were randomly divided into two groups: CG group (control group, n=9) and AG group (alcohol supplemented group, n=9). Alcohol group (3 g/kg BW) was orally supplemented every day. After the experimental period, serum components and muscle Akt, p-Akt, FoxO, p-FoxO, MuRF1, and P38 protein expressions were analyzed. In the results, the values of EDL and soleus muscle weights of AG group did not have significant differences compared to the value of the CG group. In the serum components, the value of the serum TG concentration of AG group was significantly increased compared to the value of the CG group. The value of the p-Akt/Akt and p-FoxO/FoxO of the AG group was significantly decreased compared to the value of the CG group (p<0.01). The MuRF1 protein expression of AG group was significantly increased compared to the value of the CG group (p<0.01). However, the values of p-P38/P38 between two groups did not have any significant difference. From these results, it was suggested that 4 weeks of chronic alcohol supplementation induced muscle atrophy via activated protein degradation pathway involving the inhibition of Akt phosphorylation and increased FoxO and MuRF1 protein expression of muscle in growing rats.