CC Rats Research Articles

Cardiac Hypertrophy in Pregnant Rats, Descendants of Fructose-Fed Mothers, an Effect That Worsens with Fructose Supplementation.

The role of fructose consumption in the development of obesity, MetS, and CVD epidemic has been widely documented. Notably, among other effects, fructose consumption has been demonstrated to induce cardiac hypertrophy. Moreover, fructose intake during pregnancy can cause hypertrophy of the maternal heart. Our previous research has demonstrated that maternal fructose intake has detrimental effects on fetuses, which persist into adulthood and are exacerbated upon re-exposure to fructose. Additionally, we found that maternal fructose consumption produces changes in female progeny that alter their own pregnancy. Despite these findings, fructose intake during pregnancy is not currently discouraged. Given that cardiac hypertrophy is a prognostic marker for heart disease and heart failure, this study aimed to determine whether metabolic changes occurring during pregnancy in the female progeny of fructose-fed mothers could provoke a hypertrophic heart. To test this hypothesis, pregnant rats from fructose-fed mothers, with (FF) and without (FC) fructose supplementation, were studied and compared to pregnant control rats (CC). Maternal hearts were analyzed. Although both FF and FC mothers exhibited heart hypertrophy compared to CC rats, cardiac DNA content was more diminished in the hearts of FF dams than in those of FC rats, suggesting a lower number of heart cells. Accordingly, changes associated with cardiac hypertrophy, such as HIF1α activation and hyperosmolality, were observed in both the FC and FF dams. However, FF dams also exhibited higher oxidative stress, lower autophagy, and decreased glutamine protection against hypertrophy than CC dams. In conclusion, maternal fructose intake induces changes in female progeny that alter their own pregnancy, leading to cardiac hypertrophy, which is further exacerbated by subsequent fructose intake.

Sex- and genotype-dependent nicotine plus cue-primed reinstatement is enhanced in adolescent Sprague Dawley rats containing the human CHRNA6 3'-UTR polymorphism (rs2304297).

Large-scale human candidate gene studies have indicated that a genetic variant (rs2304297) in the alpha(α)6 nicotinic acetylcholine receptor (nAChR) subunit, encoded by the CHRNA6 gene, may play a key role in adolescent nicotine addictive behavior. We hypothesized that the polymorphism selectively enhances nicotine + cue-primed reinstatement, but not nicotine- or cue-reinstatement in α6 GG (risk) vs. α6 CC (non-risk) allele carriers, without having baseline effects on natural rewards. Using CRISPR-Cas9 genomic engineering, we developed a humanized rat line with the human gene variant of the CHRNA6 3'-UTR C 123 G polymorphism in Sprague-Dawley rats. Genetically modified adolescent male and female rats were food trained under a fixed-ratio (FR)1 schedule of reinforcement and progressively increased to FR5. Animals were implanted with catheters and began nicotine self-administration (15 μg/kg/infusion) at FR5. Upon reaching stable responding, reinforced behavior was extinguished by removal of drug and cues. Reinstatement testing began for cue only, nicotine only, and nicotine + cue in a Latin Square Design. Animals were returned to extinction conditions for 2 days minimum between testing. For natural food rewards, nicotine self-administration, progressive ratio, and extinction, adolescent male and female (α6 GG and α6 CC ) rats exhibited equivalent behaviors. Male α6 GG rats show enhanced nicotine + cue-primed reinstatement when compared with male α6 CC rats. This genotype effect on reinstatement was not seen in female rats. Our findings support the in vivo functional role of the human CHRNA6 3'-UTR SNP genetic variant in sex-dependently enhancing nicotine seeking behavior in adolescent rats. Overall, the findings support clinical and preclinical data highlighting a role of α6 nAChRs mediating sex heterogeneity in substance use and related phenotypes.

Pregnancy Is Enough to Provoke Deleterious Effects in Descendants of Fructose-Fed Mothers and Their Fetuses.

The role of fructose in the global obesity and metabolic syndrome epidemic is widely recognized. However, its consumption is allowed during pregnancy. We have previously demonstrated that maternal fructose intake in rats induces detrimental effects in fetuses. However, these effects only appeared in adult descendants after a re-exposure to fructose. Pregnancy is a physiological state that leads to profound changes in metabolism and hormone response. Therefore, we wanted to establish if pregnancy in the progeny of fructose-fed mothers was also able to provoke an unhealthy situation. Pregnant rats from fructose-fed mothers (10% w/v) subjected (FF) or not (FC) to a fructose supplementation were studied and compared to pregnant control rats (CC). An OGTT was performed on the 20th day of gestation, and they were sacrificed on the 21st day. Plasma and tissues from mothers and fetuses were analyzed. Although FF mothers showed higher AUC insulin values after OGTT in comparison to FC and CC rats, ISI was lower and leptinemia was higher in FC and FF rats than in the CC group. Accordingly, lipid accretion was observed both in liver and placenta in the FC and FF groups. Interestingly, fetuses from FC and FF mothers also showed the same profile observed in their mothers on lipid accumulation, leptinemia, and ISI. Moreover, hepatic lipid peroxidation was even more augmented in fetuses from FC dams than those of FF mothers. Maternal fructose intake produces in female progeny changes that alter their own pregnancy, leading to deleterious effects in their fetuses.

Cardiovascular Deconditioning Enhances Cardiovascular and Autonomic Response to Arterial Chemoreflex Stimulation

Cardiovascular deconditioning (CVD) due to bedrest, inactivity or exposure to microgravity impairs cardiovascular regulation and circulatory homeostasis. Cardiovascular changes associated with CVD, including resting tachycardia, decreased exercise capacity and autonomic impairments are reproduced in an animal model of CVD, hindlimb unloaded (HU) rats. Autonomic dysfunction, including blunted baroreflex function, in CVD is associated with mechanisms involving the central nervous system. We hypothesized that CVD augments the arterial chemoreflex. Male Sprague‐Dawley rats were subjected to 2 weeks hindlimb unloading (HU) to simulate CVD, or maintained at normal postural position (cage control, CC). Under inactin anesthesia, baseline heart rate (HR) was elevated in HU vs CC (381±8 bpm vs 334±6 bpm). To examine the chemoreflex, HU and CC rats (n=5–6 each) were given bolus NaCN (25, 50, 75ug/kg, iv) or acute hypoxia (12% O2, 45 seconds). NaCN dose dependently increased HR and mean arterial pressure (MAP) in HU but not CC. At the highest NaCN concentration, HU increased MAP (22±4 mmHg) and HR (16±3 bpm) more than CC MAP (8±1 mmHg) and HR (6±2 bpm). NaCN also increased splanchnic sympathetic and phrenic nerve activity (SSNA and PhrNA) in both groups, and responses tended to be greater in HU rats. Likewise, the peak hypoxic response of SSNA and PhrNA were greater in HU than CC rats (SSNA, HU 143 ± 26% vs CC 111 ± 9%; PhrAmp%; HU 382 ± 208 vs CC 300 ± 103). Exposure to NaCN or hypoxia did not change PhrFreq in either group. These data suggest that HU enhances cardiovascular responses to chemoreflex activation.Support or Funding InformationFunding: HL132836

Cyanidin 3-glucoside from Queen Garnet plums and purple carrots attenuates DSS-induced inflammatory bowel disease in rats

We have investigated whether dextran sodium sulphate (DSS)-induced inflammatory bowel disease (IBD) in rats can be ameliorated by intervention with cyanidin 3-glucoside (C3G). Rats were given either normal water (C) or 0.5% DSS (D) in drinking water for 12 weeks. C3G 8 mg/kg/day as Queen Garnet plum (Q) juice, purple carrot (P) juice or pure compound was added in food for final 6 weeks to C rats to give CQ, CP and CC groups, and to D rats to give DQ, DP and DC groups. No symptoms of IBD were observed in C, CQ, CP or CC rats. D rats had bloody diarrhoea, ileal and colonic mucosal atrophy, and inflammation. Compared to D rats, DQ, DP and DC rats showed improved stool consistency (P < 0.0001) and bleeding (P < 0.0001), reduced ileum (P < 0.0001) and colon inflammation (P < 0.0001), with no changes in gut microbiota. Thus, supplementation with C3G-containing foods may ameliorate the symptoms of IBD.

Spectral analysis of cooling induced hemodynamic perturbations indicates involvement of sympathetic activation and nitric oxide production in rats.

Oscillations in arterial pressure and heart period in response to cold stress are poorly understood. We used a telemetric device with spectral and cross-spectral analyses to assess variabilities in the heart rate (HRV) and blood pressure (BPV) of conscious rats receiving a cooling stimulus (CS) (rapid immersion of palms and soles into 4°C water) at ambient thermoneutral conditions (TC), in a cold room (CC), and when under pentobarbital anesthesia (UA). Power spectra of very low, low, and high frequencies (VLF: 0.02 to 0.2Hz, LF: 0.2 to 0.6Hz, and HF: 0.6 to 3.0Hz), dicrotic notch (Dn) and plasma nitric oxide (NO) levels were measured for statistical comparisons. When compared to resting rats (PreCS), CS evoked in rats the following hemodynamic perturbations: 1) pressor and tachycardia; 2) increases in VLFBPV, LFBPV, HFBPV, and TPBPV but decreases in VLFHRV, LFHRV, and TPHRV; 3) a positive correlation between LFBPV and VLFBPV but an inverse correlation between VLFHRV and VLFBPV and LFHRV and LFBPV; 4) high coherence value at frequency region of LF between BPV and HRV; and 5) increase of NO production and disappearance of Dn. Additionally, CS of CC and UA rats compared with TC rats evoked different patterns of hemodynamic perturbations; CC rats were activated but UA rats were inactivated. Our findings indicate that changes in VLFBPV are related to the myogenic vascular responsiveness to CS. Power spectra changes to CS are highly relevant to sympathetic activation and NO production.

PP.14.13

Objective: We aimed to describe the influence of long-term consumption of cola beverage on expressions of cardiac NO signaling proteins. Design and method: Male Wistar rats received a standard diet. Additionally, a group of rats received a commercially available cola beverage (CC, n = 12). Controls (CON, n = 7) received drinking water. We measured weight gain and triglycerides (TG), cholesterol (CHOL) levels by using standard glucometer in capillary blood drops. Blood glucose was determined by conventional oral glucose tolerance test (oGTT). In addition, heart rate (HR), systolic and diastolic blood pressures (sBP and dBP) were measured by using tail-cuff method. Protein expression was determined by Western blotting in left ventricles. Results: We observed a significantly increased body weight in CC rats (541 ± 12 g; P < 0.01) when compared to controls (443 ± 23 g). This was in accordance with significantly increased sBP (CC: 135 ± 3 mmHg vs. CON: 120 ± 4 mmHg; P < 0.01) and unaltered dBP (CC: 86 ± 1 mmHg vs. CON: 85 ± 1 mmHg; NS) and significantly increased HR (CC: 383 ± 9 mmHg vs. CON: 312 ± 15 mmHg; P < 0.01). Postprandial glycaemia was significantly changed after 60 minutes (CC: 9.3 ± 0.5 mmol/L vs. CON: 6.6 ± 0.6 mmol/L; P < 0.01) and after 90 minutes of follow up (CC: 8.3 ± 0.4 mmol/L vs. CON: 6.6 ± 0.5 mmol/L; P < 0.01). We observed a non-significant tendency of increased TG (CC: 5.2 ± 0.4 mmol/L vs. 5 ± 0.5 mmol/L; NS). Paradoxically, CHOL levels were significantly decreased (CC: 3.7 ± 0.4 mmol/L vs. 4.0 ± 0.4 mmol/L; SN). In conclusion, we found a significant increase in the expression of endothelial NO synthase (eNOS) (CC: 142 ± 26 % vs. CON: 100 ± 26 %; P < 0.01), but the protein expressions of its modulators heat shock protein 90 (hsp90) and caveolin 1 (cav-1) were significantly unchanged. Conclusions: Six months of administration of cola beverage can lead to development of cardiovascular (increased eNOS, BP, HR) and also metabolic manifestations (impaired glucose tolerance) in Wistar rat. Accordingly, we propose this model as a reliable experimental model of rat metabolic syndrome for further use in pharmacological research.

Nutritional recovery with a soybean diet after weaning reduces lipogenesis but induces inflammation in the liver in adult rats exposed to protein restriction during intrauterine life and lactation.

We evaluated the effects of postweaning nutritional recovery with a soybean flour diet on de novo hepatic lipogenesis and inflammation in adult rats exposed to protein restriction during intrauterine life and lactation. Rats from mothers fed with protein (casein) in a percentage of 17% (control, C) or 6% (low, L) during pregnancy and lactation were fed with diet that contained 17% casein (CC and LC groups, resp.) or soybean (CS and LS groups, resp.) after weaning until 90 days of age. LS and CS rats had low body weight, normal basal serum triglyceride levels, increased ALT concentrations, and high HOMA-IR indices compared with LC and CC rats. The soybean diet reduced PPARγ as well as malic enzyme and citrate lyase contents and activities. The lipogenesis rate and liver fat content were lower in LS and CS rats relative to LC and CC rats. TNFα mRNA and protein levels were higher in LS and CS rats than in LC and CC rats. NF-κB mRNA levels were lower in the LC and LS groups compared with the CC and LC groups. Thus, the soybean diet prevented hepatic steatosis at least in part through reduced lipogenesis but resulted in TNFα-mediated inflammation.

A Calcium-Deficient Diet in Rat Dams during Gestation and Nursing Affects Hepatic 11β-hydroxysteroid dehydrogenase-1 Expression in the Offspring

BackgroundPrenatal malnutrition can affect the phenotype of offspring by changing epigenetic regulation of specific genes. Several lines of evidence demonstrate that calcium (Ca) plays an important role in the pathogenesis of insulin resistance syndrome. We hypothesized that pregnant female rats fed a Ca-deficient diet would have offspring with altered hepatic glucocorticoid-related gene expression and that lactation would modify these alterations.MethodologyWe determined the effects of Ca deficiency during pregnancy and/or lactation on hepatic 11β-hydroxysteroid dehydrogenase-1 (Hsd11b1) expression in offspring. Female Wistar rats consumed either a Ca-deficient (D: 0.008% Ca) or control (C: 0.90% Ca) diet ad libitum from 3 weeks preconception to 21 days postparturition. On postnatal day 1, pups were cross-fostered to the same or opposite dams and divided into the following four groups: CC, DD, CD, and DC (first letter: original mother's diet; second letter: nursing mother's diet). All offspring were fed a control diet beginning at weaning (day 21) and were killed on day 200±7. Serum insulin and adipokines in offspring were measured using ELISA kits.Principal FindingsIn males, mean levels of insulin, glucose, and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) were higher in the DD and DC groups than in the CC group. We found no difference in HOMA-IR between the CC and CD groups in either males or females. Expression of Hsd11b1 was lower in male DD rats than in CC rats. Hsd11b1 expression in male offspring nursed by cross-fostered dams was higher than that in those nursed by dams fed the same diet; CC vs. CD and DD vs. DC. In females, Hsd11b1 expression in DC rats was higher than that in CC rats.ConclusionsThese findings indicated that maternal Ca restriction during pregnancy and/or lactation alters postnatal growth, Hsd11b1 expression, and insulin resistance in a sex-specific manner.

Abstract B66: Life-time and adult genistein consumption have opposing effects on tamoxifen's ability to prevent recurrence of mammary tumors and on unfolded protein response pathways in rats

Abstract We recently found that starting intake of isoflavone genistein (GEN) present in soyfoods at the time when mammary tumors are treated with tamoxifen (TAM) increases de novo resistance to TAM and the risk of recurrence in a new rat model of estrogen receptor positive mammary tumor dormancy. However, rats which started consuming GEN before puberty and continued through their life time were highly responsive to TAM and exhibited reduced rate of mammary tumor recurrence. In this study, we investigated potential mechanisms that may explain the findings. 95 female Sprague-Dawley rats consuming AIN93G diet were supplemented with 0 or 500 ppm GEN between postnatal days (PND) 15 to 30 (prepubertal exposure) and then were fed AIN93G diet with no GEN between PND 30 and 55. On PND 48, rats received 10 mg DMBA to induce mammary tumors, and were then divided to four dietary groups on PND 55: prepubertal GEN-adult GEN group (GG, lifelong GEN, n=20); prepubertal GEN-adult control group (GC, prepubertal GEN, n=20); prepubertal control-adult GEN (CG, adult GEN, n=20); and control-control (CC, n=35). When mammary tumor reached a size of 1.4 cm in diameter, 337 ppm TAM citrate was added to rats' diet. GG and CG rats continued also consuming GEN, and all rats in GC and 20 rats in CC groups (post-diagnosis GEN) started consuming GEN one week after the TAM treatment started. 15 CC rats were never fed GEN (C, no GEN control, n=15). Mammary tumor latency was longer in GG (p&amp;lt;0.003) and GC rats (p&amp;lt;0.095), compared to CC rats. The response of tumors to TAM treatment was classified as complete or partial response, or de novo resistant. Prepubertal and life-time GEN intake increased, and intake starting during TAM treatment reduced response to TAM (p&amp;lt;0.001). Mammary cancer recurrence rate was highest in the rats which started consuming GEN during TAM treatment, and significantly lower in life-time, prepubertal and adulthood only GEN intake groups (p&amp;lt;0.001). In the mammary gland, no changes in estrogen receptor alpha (ERα) or HER2/ErB2 protein expression in the mammary gland were seen among the groups, but estrogen receptor beta (ERβ) protein level was significantly up-regulated (p&amp;lt;0.05) in the lifelong GEN exposed animals, when compared to no GEN control or prepubertal GEN exposed animals. We also investigated changes in the unfolded protein response (UPR) pathway. Surprisingly, the active form of ATF6, ATF6 p50, was highest in the mammary gland of lifelong GEN fed rats and lowest in that of CG and C animals (p&amp;lt;0.05). Target gene expression of ATF6 p50 was investigated in the mammary gland by quantitative real-time PCR and up-regulation of Xbp1 and GRP78 mRNA level was confirmed (p&amp;lt;0.05). In the tumor, ERα and progesterone receptor (PgR) protein expression did not differ among the five groups, but HER2/ErB2 and ERβ expression were higher in GC rats when compared with rats exposed to GEN lifelong (p&amp;lt;0.05). Further, protein levels of several important components in the UPR pathway - GRP78, IRE1α, ATF4 and Beclin -were significantly lower in the mammary tumors of lifelong GEN exposed rats than in the tumors of rats that started consuming GEN as adult (p&amp;lt;0.05). Our findings suggest that the effect of prepubertal GEN exposure in increasing TAM responsiveness may be related to the differentially regulated UPR pathway: members of this pathway were activated in the normal mammary gland and downregulated in the tumors. Elevated expression of GRP78 and other UPR genes in the mammary tumors of rats that started consuming GEN for the first time during TAM treatment may be associated with high de novo resistance and recurrence rate. Citation Format: Xiyuan Zhang, Leena A. Hilakivi-Clarke. Life-time and adult genistein consumption have opposing effects on tamoxifen's ability to prevent recurrence of mammary tumors and on unfolded protein response pathways in rats. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B66.

Abstract 196: Lifetime and adulthood dietary genistein intake have opposing effect on tamoxifen resistance in rats.

Abstract High childhood and adolescent dietary intake of isoflavone genistein (GEN) in soyfoods reduces later breast cancer risk, but since GEN has estrogenic properties, it is not clear whether it is safe to start consuming it after breast cancer has been diagnosed. Using a new preclinical model, we investigated the effects of childhood, adult and/or post-diagnosis consumption of GEN on the ability of tamoxifen (TAM) to treat breast cancer. 95 female Sprague-Dawley rats consuming AIN93G diet were supplemented with 0 or 500 ppm GEN between postnatal days (PND) 15 to 30 (prepubertal exposure) and then were fed AIN93G diet with no GEN between PND 30 and 55. On PND 48, rats received 10 mg DMBA to induce mammary tumors, and were then divided to four dietary groups on PND 55: prepubertal GEN-adult GEN group (GG, n=20); prepubertal GEN-adult control group (GC, n=20); prepubertal control-adult GEN (CG, n=20); and control-control (CC, n=35). When mammary tumor reached a size of 1.4 cm in diameter, 337 ppm TAM was added to rats’ diet. GG and CG rats continued also consuming GEN, and all rats in GC and 20 rats in CC groups stated consuming GEN one week after the TAM treatment started. 15 CC rats were never fed GEN. Mammary tumor latency was longer in GG (p&amp;lt;0.003) and GC rats (p&amp;lt;0.095), compared to CC rats. The response of tumors to TAM treatment was classified as complete or partial response, or de novo resistant. Prepubertal and life-time GEN intake increased, and intake starting during TAM treatment reduced response to TAM (p&amp;lt;0.001). Mammary cancer recurrence rate was highest in the rats which started consuming GEN during TAM treatment, and significantly lower in life-time, prepubertal and adulthood only GEN intake groups (p&amp;lt;0.001). Brca1 mRNA level was highest in the mammary gland of life-time GEN consuming rats (p&amp;lt;0.05). Tumor suppressor genes p21WAF1/CIP1 and p16INK4a mRNA levels were significantly higher in both prepubertal GEN groups (GC and GG) than in CC rats (p&amp;lt;0.05), as was the expression of pro-apoptotic gene Bax (p&amp;lt;0.05). No changes in estrogen receptor (ER) protein expression in the mammary gland were seen among the groups, but progesterone receptor (p&amp;lt;0.05) and phosphorylated HER2/ErbB2 (p&amp;lt;0.05) were both expressed at a lower level in rats consuming GEN through the life-time, compared with rats which consumed GEN during adult life (CG rats). Our findings show that rats exposed prepubertally or through the life-time to GEN were at lower risk of developing TAM resistance than rats which started GEN intake in adulthood or post-diagnosis. The effect of prepubertal GEN exposure in increasing TAM responsiveness may be related to up-regulation of tumor suppressor genes Brca1, p16INK4a and p21WAF1/CIP1 in their mammary gland. Recurrence rate was highest in those rats that were consuming GEN for the first time during TAM treatment. If true for humans, women with ER+ breast cancer should not start consuming GEN during TAM treatment. Citation Format: Xiyuan Zhang, Anni Warri, Idalia Cruz, Robert Clarke, Leena A. Hilakivi-Clarke. Lifetime and adulthood dietary genistein intake have opposing effect on tamoxifen resistance in rats. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 196. doi:10.1158/1538-7445.AM2013-196

Role of nucleus tractus solitarii (nTS) hydrogen sulfide (H2S) in hindlimb unloaded rats

Cardiovascular deconditioning alters central cardiorespiratory regulation and is mimicked by hindlimb unloading (HU). Preliminary data suggest the ventilatory response to hypoxia is augmented in HU rats. Furthermore, H2S from cystathionine beta synthase (CBS) augments excitatory neurotransmission in nTS, the initial site for cardiorespiratory sensory integration. Preliminary studies suggest nTS H2S augments phrenic (PNA) and splanchnic sympathetic (sSNA) nerve activity during acute hypoxia (AH) but its influence in HU rats is unknown. To test the hypothesis that increased endogenous H2S from CBS in the nTS enhances cardiorespiratory responses to AH after HU, we examined mean arterial pressure (MAP), PNA and sSNA responses to AH (2 min; 10% O2). Baseline cardiorespiratory parameters were similar in anesthetized control (C) and HU rats. Chemoreflex activation with AH increased PNA and sSNA and decreased MAP in both groups; the depressor response was less in HU rats. Bilateral nTS microinjection of the CBS inhibitor aminooxyacetate (AOA; 1 mM, 90 nl), to decrease H2S, increased baseline MAP and sSNA in both groups. In the presence of AOA, the increase in PNA amplitude to AH tended to be blunted in CC rats; this attenuation appeared to be less in HU. AOA did not alter the sSNA response to AH in CC rats, but reduced sSNA during AH after HU. These preliminary data suggest that CBS‐derived H2S in nTS augments cardiorespiratory responses to hypoxia and this modulation is diminished after HU. HL55306

Intrauterine protein restriction combined with early postnatal overfeeding was not associated with adult-onset obesity but produced glucose intolerance by pancreatic dysfunction

We investigated if whether intrauterine protein restriction in combination with overfeeding during lactation would cause adult-onset obesity and metabolic disorders. After birth, litters from dams fed with control (17% protein) and low protein (6% protein) diets were adjusted to a size of four (CO and LO groups, respectively) or eight (CC and LC groups, respectively) pups. All of the offspring were fed a diet containing 12% protein from the time of weaning until they were 90 d old. Compared to the CC and LC groups, the CO and LO groups had higher relative and absolute food intakes, oxygen consumption and carbon dioxide production; lower brown adipose tissue weight and lipid content and greater weight gain and absolute and relative white adipose tissue weight and absolute lipid content. Compared with the CO and CC rats, the LC and LO rats exhibited higher relative food intake, brown adipose tissue weight and lipid content, reduced oxygen consumption, carbon dioxide production and spontaneous activity, increased relative retroperitoneal adipose tissue weight and unaltered absolute white adipose tissue weight and lipid content. The fasting serum glucose was similar among the groups. The area under the glucose curve was higher in the LO and CO rats than in the LC and CC rats. The basal insulinemia and homeostasis model assessment of insulin resistance (HOMA-IR) were lower in the LO group than in the other groups. The total area under the insulin curve for the LO rats was similar to the CC rats, and both were lower than the CO and LC rats. Kitt was higher in the LO, LC and CO groups than in the CC group. Thus, intrauterine protein restriction followed by overfeeding during lactation did not induce obesity, but produced glucose intolerance by impairing pancreatic function in adulthood.

Voluntary post weaning exercise restores metabolic homeostasis in offspring of obese rats

AimPhysical exercise reduces obesity, insulin resistance and dyslipidemia. We previously found that maternal obesity alters central appetite circuits and contributes to increased adiposity, glucose intolerance and metabolic disease in offspring. Here we hypothesized that voluntary exercise would ameliorate the adverse metabolic effects of maternal obesity on offspring. Methods and ResultsSprague–Dawley females fed chow (C) or high-fat diet HFD (H) were mated. Female offspring from C dams were weaned onto chow (CC); those from H dams recieved chow (HC) or HFD (HH). Half of each group was provided with running wheels (CCEX, HCEX, HHEX; n=10–12).Maternal obesity increased body weight (12%), adiposity, plasma lipids and induced glucose intolerance (HC vs CC; P<0.05). These were exaggerated by postweaning HFD (HH vs HC; P<0.01), showed doubled energy intake, a 37% increase in body weight, insulin resistance and glucose intolerance (HH vs HC; P<0.01). Exercise reduced fat mass, plasma lipids, HOMA and fasting glucose in HCEX (vs HC; P<0.05) and HHEX (vs HH; P<0.01). Values in HCEX were indistinguishable from CC, however in HHEX these metabolic parameters remained higher than the sedentary HC and CC rats (P<0.01). mRNA expression of hypothalamic pro-opiomelanocortin, and adipose tumour necrosis factor α and 11β-hydroxysteroid dehydrogenase type 1 were reduced by exercise in HHEX (vs HH; P<0.05). ConclusionWhile voluntary exercise almost completely reversed the metabolic effects of maternal obesity in chow fed offspring, it did not fully attenuate the increased adiposity, glucose intolerance and insulin resistance in offspring weaned onto HFD.

Offspring Metabolomic Response to Maternal Protein Restriction in a Rat Model of Intrauterine Growth Restriction (IUGR)

Intrauterine growth restriction (IUGR), along with postnatal growth trajectory, is closely linked with metabolic diseases and obesity at adulthood. The present study reports the time-dependent metabolomic response of male offspring of rat dams exposed to maternal adequate protein diet during pregnancy and lactation (CC) or protein deprivation during pregnancy only (IUGR with rapid catch-up growth, RC) or through pregnancy and lactation (IUGR with slow postnatal growth, RR). Plasma LC-HRMS metabolomic fingerprints for 8 male rats per group, combined with multivariate statistical analysis (PLS-DA and HCA), were used to study the impact of IUGR and postnatal growth velocity on the offspring metabolism in early life (until weaning) and once they reached adulthood (8 months). Compared with CC rats, RR pups had clear-cut alterations in plasma metabolome during suckling, but none at adulthood; in contrast, in RC pups, alterations in metabolome were minimal in early life but more pronounced in the long run. In particular, our results pinpoint transient alterations in proline, arginine, and histidine in RR rats, compared to CC rats, and persistent differences in tyrosine and carnitine, compared to RC rats at adulthood. These findings suggest that the long-term deregulation in feeding behavior and fatty acid metabolism in IUGR rats depends on postnatal growth velocity.

Alendronate Inhibits Bone Formation Response To Simulated Resistance Training During Disuse

Previously, we have demonstrated that high intensity muscle contractions and the anti-resorptive agent alendronate (ALEN) independently abolish or mitigate, respectively, reductions in cancellous bone mass during rodent hindlimb unloading (HU). PURPOSE: To assess the separate and combined effects of a reduced frequency and intensity of muscle contractions simulating resistance training (SRT) and ALEN. METHODS: Male, Sprague-Dawley rats (6-mo-old) were randomly assigned to cage control (CC, n=12), HU (HU, n=12), HU plus either ALEN (HU+ALEN, n=12), SRT (HU+SRT, n=12), or ALEN and SRT (HU+SRT/ALEN, n=12). HU+SRT and HU+SRT/ALEN rats were subjected to muscle contractions while anesthetized once every 3 days during 28-d HU (75% peak isometric strength; 4 sets of 5 reps; 1000ms isometric + 1000ms eccentric). Additionally, HU+ALEN and HU+SRT/ALEN rats received 0.01 mg/kg BW ALEN 3×/week. RESULTS: Standard histomorphometry revealed a 56% reduction in periosteal bone formation rate (BFR) at mid-shaft tibia after 28-d HU, which was not rescued by ALEN treatment. However, we observed a 2.6- and 14-fold increase periosteal and endocortical (BFR), respectively, in HU+SRT vs. CC rats. These increases in diaphyseal BFR were significantly blunted (∼35-56%) in HU+SRT/ALEN rats. At the proximal tibia metaphysis (PTM), HU reduced cancellous BFR 80%, with no effect of ALEN treatment (-85% vs. CC). Similar to diaphyseal results, SRT during HU significantly increased cancellous BFR 123% vs. CC, whereas HU+SRT/ALEN inhibited the anabolic effect of SRT and reduced BFR (-33% vs. CC). SRT prevented negative effects of HU on PTM cancellous microarchitecture, resulting in increased bone volume (+19%) and trabecular thickness (+9%), respectively vs. CC. Additionally, osteoclast surface (OcS/BS) was reduced (-57%) and osteoid surface (OS/BS) significantly increased in HU+SRT rats vs. CC (32%). Adding ALEN to SRT during HU reduced OcS/BS (-75%), ObS/BS (-72%), and OS/BS (-61%) vs. CC, but did not affect microarchitecture. CONCLUSION: These results demonstrate the anabolic effect of high intensity muscle contractions during disuse and suggest that both bone resorption and formation are suppressed when SRT is combined with bisphosphonate treatment during HU. Funded by NSBRI through NASA Cooperative Agreement NCC 9-58.

Effects of cysteine on metformin pharmacokinetics in rats with protein-calorie malnutrition: partial restoration of some parameters to control levels

Metformin is metabolized primarily via hepatic microsomal cytochrome P450 (CYP)2C11, CYP2D1 and CYP3A1/2 in rats. The expression and mRNA levels of hepatic CYP2C11 and CYP3A1/2 are decreased in rats with protein-calorie malnutrition (PCM), but these levels are fully or partially restored to control levels in PMC rats by oral cysteine supplementation (PCMC rats). Thus, it would be expected that the pharmacokinetic parameters of metformin in PCM rats would be returned to control levels in PCMC rats. Metformin was administered i.v. (100 mg kg(-1)) and orally (100 mg kg(-1)) to control, CC (control rats with oral cysteine supplementation), PCM and PCMC rats. The following pharmacokinetic parameters of metformin following i.v. administration were restored from levels in PCM rats to levels in control rats in PCMC rats: intrinsic clearance (0.0350, 0.0309, 0.0253 and 0.0316 mL min(-1) mg(-1) protein for control, CC, PCM, and PCMC rats, respectively), total area under the plasma concentration-time curve from time zero to time infinity (AUC; 4110, 4290, 5540 and 4430 microg min mL(-1), respectively), and time-averaged non-renal clearance (8.12, 7.95, 5.94 and 8.17 mL min(-1) kg(-1), respectively). AUC values following oral administration were comparable between control and PCMC rats (1520, 1480, 2290 and 1680 microg min mL(-1), respectively).

Soybean diet alters the insulin-signaling pathway in the liver of rats recovering from early-life malnutrition

ObjectiveWe investigated if alterations in the insulin-signaling pathway could contribute to reduced hepatic glycogen levels in adult rats subjected to a protein deficiency during intrauterine life and lactation and reared through to recovery on a soybean diet. MethodsRats from mothers fed with 17% or 6% protein (casein) during pregnancy and lactation were maintained with a 17% casein diet (offspring born to and suckled by mothers fed a control diet and subsequently fed the same diet after weaning [CC group] and offspring born to and suckled by mothers fed a control diet and subsequently fed a soybean flour diet with 17% protein after weaning [CS group]), a soybean diet (offspring of mothers fed a low-protein diet and a control diet after weaning [LC group] and offspring of mothers fed a low-protein diet and fed a soybean flour diet containing 17% protein after weaning [LS group]), or a 6% casein diet (offspring of mothers fed a low-protein diet and subsequently fed the same diet after weaning [LL group]) from weaning until 90 d of life. ResultsA soybean diet did not modify basal serum glucose and glucagon concentrations, but raised basal serum insulin and consequently increased the serum insulin/glucose ratio. Insulin receptor and insulin receptor substrate-1 levels were lower in rats fed a soybean diet compared with those maintained with a casein diet. In the LS group, the p85 levels were higher than in the LC group, whereas in CS rats its expression was lower than in CC rats. The expression of p110 was lower in the CS group compared with the CC group and similar in the LS and LC groups. Insulin receptor substrate-1 phosphorylation was similar in the LS, LC, and CS groups and lower compared with the CC group. The insulin receptor substrate-1–p85/phosphatidylinositol 3-kinase association was lower in LS than in LC rats and in CS than in CC rats. Akt phosphorylation was lower in the CS and LS groups than in the CC and LC groups. ConclusionAdult rats maintained with a soybean diet exhibited insulin resistance due, at least in part, to alterations in the early steps of the insulin signal transduction pathway.

Soybean diet modulates acetyl-coenzyme A carboxylase expression in livers of rats recovering from early-life malnutrition

Objective The present study evaluated the effect of nutritional recovery with a soybean diet on the gene and protein expressions and protein phosphorylation of several enzymes and transcription factors involved in hepatic lipid metabolism. Methods Rats from mothers fed with 17% or 6% protein (casein) during pregnancy and lactation were maintained with a 17% casein (CC and LC groups) or soybean (CS and LS groups) diet and with a 6% casein (LL group) diet until 90 d of life. Results The soybean diet enhanced serum insulin levels but decreased body and liver weights and hepatic lipid and glycogen concentrations. Liver peroxisome proliferator receptor-α mRNA abundance was higher in the LS and CS groups than in the LC and CC groups, but the protein content was similar in all groups. Hepatic acetyl-coenzyme A carboxylase (ACC)-α and ACCβ mRNA expression was markedly lower in the LS and CS rats than in the LC and CC rats. ACC protein expression was lower in the CS group than in the CC, LC, and LS groups. Phospho-[Ser 79]2-ACC content was similar in the CS, LC, and LS groups and lower than the CC group. In the CS rats this reduction paralleled the decrease in total ACC protein. Messenger RNA and protein expression of sterol regulatory element-binding protein 1c, adenosine monophosphate-activated protein kinase, and phospho-[Thr 172]-adenosine monophosphate-activated protein kinase was not modified by the soybean diet. Conclusion Thus, the soybean diet reduced the liver lipid concentration through downregulation of the ACC gene and protein expressions rather than by phosphorylation status, which possibly resulted in decreased lipogenesis and increased β-oxidation.

Intermittent postural recovery during 14 days of hindlimb unloading (HU) is not sufficient to restore cardiac autonomic imbalance in rats

Previous data indicate that 14 days of continuous HU in rats produces cardiac autonomic imbalance. We hypothesized that a daily period of normal posture may resolve these effects. Male, Sprague‐Dawley rats were randomly assigned to control (CC; n=3), continuous HU (HUC; n=4) or intermittent HU (HUI; n= 5) groups. Control rats were maintained in the normal posture. HUC rats underwent continuous elevation of the hindlimbs for 14‐days while HUI rats were returned to the normal posture for 30 minutes each day during the HU procedure. On the 14th day, mean arterial pressure (MAP) and heart rate (HR) were measured followed by selective cardiac autonomic blockade administered via i.v. injection of methylatropine and propranolol. Both HU groups exhibited significant resting tachycardia compared to CC rats, but HR was lower in HUI vs. the HUC group (CC: 366±3.9; HUC 474±7.5; HUI: 434±1.6 bpm). However, both HU groups had significantly less parasympathetic (CC: 60±7.7; HUC: 25±10.9; HUI: 15±5.2 Δbpm) and greater sympathetic cardiac tone (CC: 16±7.9; HUC: 91±10.9; HUI: 77±9.2 Δbpm) than CC rats, with no difference between HU groups with respect to either autonomic parameter. Baseline MAP was not different among any of the groups. Data indicate that while daily recovery from HU may partially restore resting HR, it is not a sufficient stimulus to reverse the autonomic imbalance produced by HU‐induced deconditioning. (Supp. by: NIH HL14388 &amp; DK 066086).