Pregnant Rabbits Research Articles

Evaluation of the Developmental Toxicity of Vedolizumab, an α4β7 Receptor Antagonist, in Rabbit and Nonhuman Primate.

Vedolizumab, a humanized monoclonal antibody approved for the treatment of adults with moderately to severely active ulcerative colitis or Crohn disease, targets α4β7 integrin and selectively blocks gut-specific lymphocyte trafficking. The potential effects of vedolizumab on development were assessed by standard preclinical toxicity studies in rabbits and cynomolgus monkeys. A single infusion of vedolizumab (0, 10, 30, or 100 mg/kg) was administered intravenously to pregnant rabbits on gestational day 7; rabbits were monitored to gestational day 29. Vedolizumab (0, 10, or 100 mg/kg) was administered intravenously every 2 weeks to pregnant cynomolgus monkeys beginning on gestational day 20 with the last dose on gestational day 132 (9 doses total). In rabbits, vedolizumab did not affect maternal net body weight or net gains, gravid uterine weights, or mean maternal food consumption, nor did it affect intrauterine growth or fetal survival. There were also no vedolizumab effects on embryo–fetal development compared to controls. In cynomolgus monkeys, there was no increase in prenatal loss/death or stillbirth and no maternal toxicity associated with vedolizumab. On day 28 postpartum, low levels of vedolizumab were detected in the breast milk of 3 of 11 monkeys in the 100 mg/kg group. No vedolizumab-related effects on the number of infants born, infant development, or animal hematology or clinical chemistry were noted. Administration of vedolizumab to pregnant rabbits and cynomolgus monkeys did not show any potential for maternal or developmental effects.

Ultrasonographic evaluation of feto-placental tissues at different intrauterine locations in rabbit

The main purpose of examining multiparous species with real-time ultrasonography is to determine the gestational age and make various fetal measurements for early diagnosis of growth anomalies and sibling mismatches. This study investigated changes in fetometric measurements, obstetric Doppler indices and placental image analysis results based on gestational age and fetal location in fetuses located cranially and caudally between 16 and 24 days gestation in 22 healthy pregnant New Zealand rabbits. The first study group consisted of fetuses positioned at the cranial end (n = 22) while the second group consisted of fetuses positioned at the caudal end (n = 22) in each pregnancy. Fetal biparietal head diameter (BPD) and trunk diameter (TD) were measured, and mean grayness values (MGV) were determined from placental image analysis of each fetus. Using Doppler USG, the pulsatile (PI) and resistance (RI) indices of the uterine artery (UtA) and umbilical artery (UmA) were recorded. By the end of the study, BPD and TD values for cranial and caudal fetuses had significantly increased with gestational age (P < 0.001). The MGV values of caudal fetuses were significantly higher (except for the 16th day) (P < 0.05). The UtA PI value of the caudal fetuses was significantly higher (except for the 18th day) (P < 0.01). The UtA RI values of caudal fetuses were significantly higher than cranial ones on the 16 and 24th days (P < 0.05). The PI of the UmA increased until the 20th day before decreasing significantly in both study groups (P < 0.001). The UmA RI value decreased according to the gestational age in both groups (P < 0.001). It was significantly higher in the caudal fetuses on the 20th day (P < 0.05). The somatic rate of all fetuses peaked at the end of the second trimester, although caudal fetuses had higher fetometric values, and this location difference also affected placental echotexture. In both vessels of caudal fetuses, pulsatility and resistance values were higher. The 20th day of pregnancy was a threshold for the Doppler exam results. In conclusion, growth and metabolic status of fetuses located in different uterine locations in healthy pregnant New Zealand rabbits vary. Based on the these growth curves and hemodynamic data, more comprehensive studies of intrauterine life may be possible.

Impact of Some Medicinal Plants Supplement on Pregnant Rabbits Diet During Hot Summer Season

Impact of Some Medicinal Plants Supplement on Pregnant Rabbits Diet During Hot Summer Season

Ascending Lipopolysaccharide-Induced Intrauterine Inflammation in Near-Term Rabbits Leading to Newborn Neurobehavioral Deficits

Background: Chorioamnionitis from ascending bacterial infection through the endocervix is a potential risk factor for cerebral palsy. Tetrahydrobiopterin, an essential cofactor for nitric oxide synthase (NOS) and amino acid hydroxylases, when augmented in the fetal brain, prevents some of the cerebral palsy-like deficits in a rabbit hypoxia-ischemia model. Objectives: To study the effect of lipopolysaccharide (LPS)-induced intrauterine inflammation in preterm gestation on motor deficits in the newborn, and whether biosynthesis of tetrahydrobiopterin or inflammatory mediators is affected in the fetal brain. Methods: Pregnant rabbits at 28 days gestation (89% term) were administered either saline or LPS into both endocervical openings. One group underwent spontaneous delivery, and neurobehavioral tests were performed at postnatal day (P) 1 and P11, with some kits being sacrificed at P1 for histological analysis. Another group underwent Cesarean section 24 h after LPS administration. Gene sequences for rabbit biosynthetic enzymes of tetra­hydrobiopterin pathways were determined and analyzed in addition to cytokines, using quantitative real-time polymerase chain reaction. Results: Exposure to 200 μg/kg/mL LPS caused a locomotion deficit and mild hypertonia at P1. By P11, most animals turned into normal-appearing kits. There was no difference in neuronal cell death in the caudate between hypertonic and nonhypertonic kits at P1 (n = 3–5 in each group). Fetal brain GTP cyclohydrolase I was increased, whereas sepiapterin reductase and 6-pyruvoyltetrahydropterin synthase were decreased, 24 h after LPS administration. Neuronal NOS was also increased. Regardless of the position in the uterus or the brain region, expression of TNF-α and TGF-β was decreased, whereas that of IL-1β, IL-6, and IL-8 was increased (n = 3–4 in each group). Conclusions: This is the first study using an ascending LPS-induced intrauterine inflammation model in rabbits, showing mostly transient hypertonia and mainly locomotor deficits in the kits. Not all proinflammatory cytokines are increased in the fetal brain following LPS administration. Changes in key tetrahydro­biopterin biosynthetic enzymes possibly indicate different effects of the inflammatory insult.

Sildenafil for Antenatal Treatment of Congenital Diaphragmatic Hernia: From Bench to Bedside.

Persistent pulmonary hypertension (PPH) is one of the main causes of mortality and morbidity in infants affected by congenital diaphragmatic hernia (CDH). Since the structural changes that lead to PPH take place already in utero, a treatment starting in the prenatal phase may prevent the occurrence of this complication. To summarize the development process of antenatal sildenafil for CDH. The pharmacokinetics and efficacy of sildenafil have been assessed in the rat and the rabbit model. The transfer of the drug through the human placenta has been measured with the ex-vivo placenta perfusion model. Results from this experiment are being incorporated in a pregnancy-physiologically based pharmacokinetic (p- PBPK) model. A phase I-IIb placental transfer and safety study is ongoing. Sildenafil administration to pregnant rats and rabbits led to therapeutic foetal drug levels without maternal and foetal toxicity, although it was associated with impaired vascular development in foetuses with nonhypoplastic lungs. Peak concentrations and 24-hour exposure were higher in pregnant rabbits compared to nonpregnant ones. In rat and rabbit foetuses with CDH, sildenafil rescued the lung vascular anomalies and partially improved parenchymal development. Sildenafil crossed the human placenta at a high rate ex-vivo, independently from the initial maternal concentration. There is preclinical evidence that maternally administered sildenafil prevents the vascular changes that lead to PPH in CDH newborns. The phase I/IIb clinical study together with the p-PBPK model will define the maternal dose needed for a therapeutic effect in the foetus. Foetal safety will be investigated both in the clinical study and in the sheep. The final step will be a multicentre, randomized, placebo-controlled trial.

Hormonal Changes in Relation to Productivity of Pregnant Rabbit Does.

Hormonal Changes in Relation to Productivity of Pregnant Rabbit Does.

Effects of Induced Haemorrahge on Thermoregulation, Blood Constituents and Serum Biochemical Parameters in Pregnant and Non-Pregnant Rabbits (Oryctolagus cuniculus)

Background and Objectives: Haemorrhage is a leading cause of mortality and morbidity of mother and foetus. Pregnancy is associated with changes which may influence responses to bleeding. This study was designed to examine the influence of controlled haemorrhage and compare thermoregulation and haematological and biochemical parameters in pregnant and nonpregnant rabbits.&#x0D; Materials and Methods: Twelve pregnant and nonpregnant rabbits, 6 in each group, were used in the studies. Both groups of animals were subjected to 20% haemorrhage of total blood volume on gestation day 21. The rectal temperature (Tr), respiratory rate (RR) and heart rate (HR) were monitored for 2 days following bleeding. Blood samples were collected at 24 hrs before induction of bleeding and then after bleeding at 30 min, 24 hrs and 48 hrs. The samples were used for measurements of haematological parameters; coagulation profile, arterial blood gases and serum electrolytes.&#x0D; Results: The general trend indicates lower Tr values in pregnant rabbits at 30 min post-haemorrhage. The values of RR and HR were significantly (P ≤ 0.01) higher in pregnant and nonpregnant animals at 24 hrs post-haemorrhage. The pregnant rabbits showed significant (P&lt;0.05) decrease in platelets count at 24 hrs post-haemorrhage compared to the nonpregnant values. In pregnant rabbits, haemorrhage was associated with significant increase in PT. The activated partial thromboplastin time (APTT) was significantly (P≤ 0.01) prolonged at 24 hrs post-haemorrhage in pregnant and nonpregnant rabbits. The partial pressure of arterial oxygen (PaO2) in pregnant and nonpregnant rabbits was significantly (P≤ 0.01) increased at 24hrs and 48 hrs post-haemorrhage. The partial pressure of arterial carbon dioxide (PaCO2) decreased significantly (P≤0.01) at 30 min post-haemorrhage in pregnant rabbits. There was a slight increase in Na and Ca levels in pregnant rabbits’ post-haemorrhage. Haemorrhage in rabbits was associated with significant decreases in plasma osmolality in pregnant rabbits.&#x0D; Conclusion: Pregnancy induces modifications in some physiological responses to haemorrhage. The information generated could be used in monitoring maternal health during pregnancy and risks of changes associated with haemorrhage in mammals.

Inhibition of the PI3K/Akt signaling pathway impedes the restoration of neurological function following hypoxic-ischemic brain damage in a neonatal rabbit model.

Hypoxic-ischemic brain damage (HIBD), frequently occurring in infancy and childhood, is a major cause of mortality and severe neurologic impairment. This study was performed to examine the effect of the PI3K/Akt signaling pathway on HIBD in a neonatal rabbit model. Uterine artery occlusion was used to establish HIBD models in neonatal rabbits, which were then subjected to sham operation, dimethyl sulfoxide (2 mL) or LY294002 (inhibitor of PI3K/Akt signaling pathway, 6.4 μg/kg). Behavioral neurological assessment was performed in neonatal rabbits delivered by cesarean section, after which serum neuron-specific enolase (NSE) level and cerebral water content were determined. The level of cleaved caspase-3 level and apoptosis of neurons were observed by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Furthermore, the expression of PI3K/Akt signaling pathway- and apoptosis-related factors was examined. In neonatal rabbits, HIBD increased the fetal death rate; reduced neurological scores of posture, righting reflex, and deglutition reflex; elevated serum NSE levels, cerebral water content, cleaved caspase-3-positive expression in hippocampal CA1 region and apoptotic neurons; inactivated PI3K/Akt signaling pathway as well as reduced Bcl-2 expression and increased BAD and Bax expression. Notably, the treatment of LY294002 further aggravated neurological impairment in neonatal rabbits in response to HIBD. Following the HIBD caused by intrauterine asphyxia, the LY294002 administered through auricular vein infusion into pregnant rabbits exacerbates neurological impairment of neonatal rabbits, suggesting that inhibition of PI3K/Akt signaling pathway may serve as a candidate therapeutic target for neurological recovery.

Hepatitis E-related adverse pregnancy outcomes and their prevention by hepatitis E vaccine in a rabbit model

ABSTRACT Hepatitis E virus (HEV) can lead to high mortality during pregnancy. This study was to investigate the adverse pregnancy outcomes caused by different HEV genotypes and their prevention by HEV 239 vaccine in rabbits. Forty-two female rabbits were randomly and equally divided into 7 groups (A-G). HEV 239 vaccine and a placebo were administered to groups E (10 μg×2), F (5 μg×2) and G (1 mL of PBS×2) before copulation. After pregnancy, 1 mL of 1.5×106 copies/mL rabbit HEV3 was inoculated to groups A, E, F and G, swine HEV4/human HEV3 to groups B/C, and group D was a negative control. Anti-HEV antibody, HEV RNA, and alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels were monitored. Pregnant rabbits infected by HEV manifested HEV infection symptoms including fecal virus shedding, ALT/AST elevation, and histopathological changes, and adverse pregnancy outcomes. Immunized pregnant rabbits in groups E and F showed no HEV infection symptoms and adverse outcomes. The newborn rabbits delivered by pregnant rabbits with/without immunization showed without/with HEV infection symptoms. This study demonstrated that multiple genotypes of HEV infection can cause adverse outcomes and HEV 239 vaccine can prevent HEV-related adverse outcomes in pregnant rabbits.

Surgical technique for developing a rabbit model of congenital diaphragmatic hernia and tracheal occlusion

The surgical model of congenital diaphragmatic hernia (CDH) has been utilized in exploring treatments and innovative therapies, such as tracheal occlusion (TO). The rabbit is an excellent surgical model compared to others due to lower cost, ease of care, short gestational period, and large litter size. This model is also ideal in studying lung hypoplasia of CDH because rabbit lung development is most similar to humans as alveolarization begins prior to birth and continues post-natally. However, the surgical technique in creating a rabbit model of CDH is quite difficult and information is lacking on how to establish this model. Therefore, the aim of this paper is to describe:•Surgical technique in establishing a rabbit model of CDH and TO•Perioperative care for pregnant rabbit does

Productive performance, metabolic, and hematologic parameters of pregnant nulliparous rabbit does according to dietary protein level.

Objective:This study aims at investigating the productive performance, metabolic, and hematological profiles of Algerian local rabbits does during their first pregnancy and according to dietary protein content.Materials and methods:A total of 52 nulliparous rabbit does, 3,116 ± 72.9 g live weight, were allocated individually to three groups (17/18 females per group) being on isoenergetic diets [2,600 kcal Digestible Energy (DE)/kg] that differ in their digestible protein content by 15%, 17%, and 19%, respectively, for L, M, and H diets. All these diets were provided ad libitum.Results:The use of a high protein diet did not affect does weight and feed intake during the pregnancy period. Statistically, no significant difference (p > 0.05) was recorded in born or alive litter size and birth weight. There was no effect of diet and sampling time (p > 0.05) on plasma metabolites but there were significant effects of sampling time (p < 0.0001) on the metabolic parameters studied with prolificacy used as a covariate. Hematologic indices in pregnant rabbits were not affected by the diet exceeded the red blood cells rate that increased significantly (p < 0.05) with the increase in dietary protein content during the different periods of gestation.Conclusion:The use of a high protein diet has no effect on weight during the pregnancy period. No effect of diet and sampling time on plasma metabolites and hematological profiles are recorded; however, significant effects of sampling time are recorded on the metabolic parameters.

THE RELATIONSHIP BETWEEN LEPTIN HORMONE LEVELS AND RABBIT DOES PERFORMANCE DURING PREGNANCY PERIOD

A total number of 30 primiparous New Zealand White (NZW) pregnant rabbit, does were used in the current study to evaluate the changes of leptin levels during pregnancy in relation to each of physiological, reproductive and productive performance of does. Rabbits aged 5-6 months and weighed 3098.15 ± 20.24 g on average. Plasma biochemical parameters were determined at 13, 21, 28 days of pregnancy and at kindling day. Also, the does weigh, litter size, litter weight, milk yield and milk compositions were determined. The results showed that,leptin levels increased slightly during gestation days, reached to the highest value (2.91 ng/ml) at day 28 of pregnancy and then declined at delivery day. Furthermore, leptin levels positively correlated with GST and negativelywith H2O2and MDA. Both H2O2and MDA were at the lower levels day 28 of pregnancy when leptin recorded its highest level (2.91 ng/ml). This clear that, leptin may play an important role in the system of antioxidant and free radicals. Blood proteins (TP, Alb and A/G, except Glb) were associated positively with leptin levels. This indicates that, leptin may interfere with blood proteins metabolism. Furthermore, leptin correlated negatively with plasma TL, TG and Glu which declined during gestation days and recorded their lower values (154.47,135.11 and 106.55 mg/dl, respectively) at day 28 of pregnancy. Additionally, leptin also was in a negative relationship with BUN levels, which were higher than normal range at days 13 and 21 of pregnancy. Afterwards, significantly declined at day 28.Also, CR levels correlated negatively with leptin levels. The liver enzymes (AST and ALT) were in a negative relationship with leptin levels. These enzymes declined during gestation days recorded their lower values at day 28 of pregnancy, respectively. Also,body weight of dam, litter weights and size were positively associated with leptin levels, because leptin play an important role in regulating BW by controlling the mass of adipose tissue. Additionally, the results showed a negative relationship between leptin levels and milk yield, MF, ML and milk ash. In contrast, MP, MTS and MSNF were associated positively with leptin levels. In conclusion, the study clarified the importance of leptin levels during pregnancy period in primiparous rabbit does through its relationship with blood parameters and the productive performance of both dam and the kits. However, its relationship with these parameters need further studies, especially, studies on rabbits are very rare and most of them have been conducted on other species.

Activation of cortical and striatal regions during the expression of a naturalistic compulsive-like behavior in the rabbit

Nest building behavior in the pregnant rabbit (Oryctolagus cuniculus) can serve as a model for compulsions in obsessive compulsive disorder (OCD). Previous work showed that the “straw carrying” phase of nest building (during which the rabbit repeatedly collects straw in its mouth, carries it into the nest box and deposits it there, and then returns to collect more) is associated with increased c-FOS expression (a marker of neuronal activity) in the orbitofrontal, anterior cingulate, and piriform cortices. In the present study, we quantified c-FOS expression in the caudate and putamen, as well as in the primary motor, somatosensory, and prefrontal cortices of: (1) pregnant rabbits given straw (PREG + STRAW); pregnant rabbits not given straw (PREG); (3) estrous rabbits given straw (ESTROUS + STRAW); and (4) estrous rabbits not given straw (ESTROUS). We found that straw carrying was associated with increased c-FOS expression in the dorsal putamen, ventral caudate, primary motor cortex, and somatosensory cortex. Additionally, a correlational analysis of PREG + STRAW animals revealed that these regions, along with the premotor and prelimbic cortices, were significantly intercorrelated with respect to c-FOS expression, suggesting their “coactivation” during repetitive straw carrying. By contrast, behavioral interactions of non-pregnant (ESTROUS) rabbits with straw (e.g., sniffing, nibbling it) were associated with a distinct pattern of c-FOS expression that included the medial and ventral putamen. c-FOS expression in PREG + STRAW rabbits is similar to patterns of regional brain activity in OCD patients exposed to obsession-provoking stimuli, as well as to those observed in healthy human mothers responding to infant-associated stimuli.

Species differences in the developmental toxicity of procymidone-Placental transfer of procymidone in pregnant rats, rabbits, and monkeys.

To clarify species differences in the developmental toxicity of procymidone (Sumilex®, a fungicide for agricultural use), placental transfer studies were conducted using 14C-labeled procymidone in pregnant rats, rabbits, and monkeys. These studies demonstrated that maternal-to-fetal transfer of the parent compound and its hydroxylated metabolite, which are both weak anti-androgenic agents, occurred more easily than that of other metabolites, with much higher absolute concentrations achieved in the fetal circulation of rats than of rabbits or monkeys. Notably, in rats, the fetal plasma concentration of the hydroxylated metabolite was higher than that of procymidone, especially after repeated oral administration of procymidone. These results suggest that the hydroxylated metabolite is the most relevant metabolite involved in teratogenic activity in rats.

Embryo–fetal toxicity assessment of vonoprazan in rats and rabbits

Vonoprazan is a new potassium-competitive acid blocker to treat acid-related diseases. However, its safety during pregnancy is unclear. The aim of the study was to investigate the potential reproductive toxicity on the embryo-fetal development of vonoprazan. Vonoprazan acetate was administered by intravenous injection to pregnant rats (0, 2, 6 and 20mgkg-1 day-1 ) and rabbits (0, 1.2, 3.6 and 12mgkg-1 day-1 ) during the organogenetic period (gestation day 6-15 [rats] and 6-18 [rabbits]). Maternal reproductive endpoints were evaluated, together with effects on fetal growth and morphological development. In rats, no treatment-related effects were found in the highest dose group (20mgkg-1 ) and the maternal plasma exposure was ≥50-fold the expected clinical human exposure. However, in rabbits, dose-related clinical signs (soft or liquid feces) occurred in the 12mgkg-1 group, which was regarded as a maternal toxicity. Besides, decreased maternal weight gain also was considered as a minimal maternal toxicity. At 12mgkg-1 , delayed fetal ossification was found as evidence of embryo-fetal growth retardation, which was related to decreased fetal and placental weights. There was no maternal and developmental toxicity in the 1.2 and 3.6mgkg-1 groups. Thus, the no-observed-adverse-effect levels of vonoprazan acetate in rabbits are considered 3.6mgkg-1 day-1 , which produced plasma exposure that was about 18-fold human clinical exposure.

Nutritional intra-amniotic therapy increases survival in a rabbit model of fetal growth restriction.

ObjectiveTo evaluate the perinatal effects of a prenatal therapy based on intra-amniotic nutritional supplementation in a rabbit model of intrauterine growth restriction (IUGR).MethodsIUGR was surgically induced in pregnant rabbits at gestational day 25 by ligating 40–50% of uteroplacental vessels of each gestational sac. At the same time, modified-parenteral nutrition solution (containing glucose, amino acids and electrolytes) was injected into the amniotic sac of nearly half of the IUGR fetuses (IUGR-T group n = 106), whereas sham injections were performed in the rest of fetuses (IUGR group n = 118). A control group without IUGR induction but sham injection was also included (n = 115). Five days after the ligation procedure, a cesarean section was performed to evaluate fetal cardiac function, survival and birth weight.ResultsSurvival was significantly improved in the IUGR fetuses that were treated with intra-amniotic nutritional supplementation as compared to non-treated IUGR animals (survival rate: controls 71% vs. IUGR 44% p = 0.003 and IUGR-T 63% vs. IUGR 44% p = 0.02), whereas, birth weight (controls mean 43g ± SD 9 vs. IUGR 36g ± SD 9 vs. IUGR-T 35g ± SD 8, p = 0.001) and fetal cardiac function were similar among the IUGR groups.ConclusionIntra-amniotic injection of a modified-parenteral nutrient solution appears to be a promising therapy for reducing mortality among IUGR. These results provide an opportunity to develop new intra-amniotic nutritional strategies to reach the fetus by bypassing the placental insufficiency.

Embryo-fetal development studies with the dietary supplement vinpocetine in the rat and rabbit.

Dietary supplement and natural product use is increasing within the United States, resulting in growing concern for exposure in vulnerable populations, including young adults and women of child-bearing potential. Vinpocetine is a semisynthetic derivative of the Vinca minor extract, vincamine. Human exposure to vinpocetine occurs through its use as a dietary supplement for its purported nootropic and neuroprotective effects. To investigate the effects of vinpocetine on embryo-fetal development, groups of 25 pregnant Sprague-Dawley rats and 8 pregnant New Zealand White rabbits were orally administered 0, 5, 20, or 60 mg vinpocetine/kg and 0, 25, 75, 150, or 300 mg/kg daily from gestational day (GD) 6-20 and GD 7-28, respectively. Pregnant rats dosed with vinpocetine demonstrated dose-dependent increases in postimplantation loss, higher frequency of early and total resorptions, lower fetal body weights, and fewer live fetuses following administration of 60 mg/kg, in the absence of maternal toxicity. Additionally, the rat fetuses displayed dose-dependent increases in the incidences of ventricular septum defects and full supernumerary thoracolumbar ribs. Similarly, albeit at higher doses than the rats, pregnant rabbits administered vinpocetine displayed an increase in postimplantation loss and fewer live fetuses (300 mg/kg), in addition to significantly lower fetal body weights (≥75 mg/kg). In conclusion, vinpocetine exposure resulted in similar effects on embryo-fetal development in the rat and rabbit. The species differences in sensitivity and magnitude of response is likely attributable to a species difference in metabolism. Taken together, these data suggest a potential hazard for pregnant women who may be taking vinpocetine.

The different effects of linseed and fish oil supplemented diets on insulin sensitivity of rabbit does during pregnancy

This study investigates the effects of linseed (rich in ɑ-linolenic acid (ALA)) and fish oil (rich in eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)) supplementation on the insulin resistance of pregnant rabbits. Two months before insemination, the rabbits (15 animals/group) were fed different diets: commercial standard (group C), supplemented with 10% extruded linseed (group L), and 3% fish oil (group FO). The L group does showed both the highest feed intake before AI (P < 0.01) and the highest body weight (BW) throughout pregnancy (P < 0.001). The L does yielded less milk than the C does (P < 0.001); however, no differences were observed in either weight or size of litter at weaning. Regardless of diet, insulin concentrations and HOMA-IR values were higher during the first half of pregnancy (P < 0.001). Nevertheless, the L does showed higher mean insulin concentrations than FO rabbits (P < 0.01) and the lowest glucose clearance (P < 0.01) during pregnancy. On the other hand, pregnant FO rabbits showed the lowest glucose concentrations (P < 0.05) and the lowest Homeostasis model assessment values for insulin resistance (HOMA-IR, P < 0.05) as well as a faster restoration of baseline glucose levels following glucose load (P < 0.001). Before and during pregnancy, the BW of the rabbits was positively related to fasting sample- and tolerance test-derived indices of insulin resistance (P < 0.05) suggesting that a high pre-pregnancy BW predisposes to gestational insulin resistance. Linseed supplementation increased BW and predisposed to insulin resistance during pregnancy; whereas, fish oil improved insulin sensitivity without significant changes in BW.

Alizarin Red-S Protocol for Skeletal Staining during Fetal Period in Rabbit

Background: The main purpose of this study was to give detailed information on the staining protocol of Alizarin Red-S to detect the normal and abnormal skeleton of rabbit fetus. Methods: Eleven (9 females and 2 males) of adult rabbit weighing 3-3.5 kg were used. The female rabbits were left with buck to become pregnant then were classified into a treatment and a control group. The former group received oral doses of 400mg/kg of sodium valproate for 15 days starting from the 6th day after mating until 20th day of pregnancy, while the second received water in the same period. The pregnant rabbit was slaughtered at the 29th day of pregnancy. The live rabbit fetuses were collected. The staining protocol included fixation, dehydration, clearing, staining and preservation. The fetuses were examined under dissecting microscope and photos were taken for documentation. Results: The staining protocol made the rabbit fetuses to be clear enough to see their skeleton through the surrounding tissue. The axial skeleton including skull with mandible, vertebral column, ribs and sternum and the appendicular skeleton including the bones of the fore-and hindlimbs took the stain and became red in color. The macroscopic skeletal disorders of the fetuses of the treatment group were observed. The ossification centres were assessed. Conclusion: This protocol which depended on fixation by 95% ethanol, clearing by 1% potassium hydroxide and staining by 0.001 % Alizarin Red-S was effective in detecting normal and abnormal fetal skeletal morphology.

Pregnancy affects the pharmacokinetics of sildenafil and its metabolite in the rabbit

1. There is growing interest in the use of sildenafil during pregnancy for various maternal and fetal conditions. This study aims to investigate the effect of pregnancy on the maternal pharmacokinetics (PK) of sildenafil and its main metabolite desmethylsildenafil in rabbits. Using NONMEM, population PK modeling was performed based on plasma samples from 31 rabbits of whom 15 were pregnant and 16 were not. All received a single subcutaneous sildenafil dose of 10 mg/kg. One sample was obtained per rabbit at either 30, 60, 120, 360, 720 or 1320 min after sildenafil administration.2. A two- and one-compartment PK-model best described the data for sildenafil and desmethylsildenafil, respectively. Compared to non-pregnant rabbits, the central and peripheral volume of distribution and inter-compartmental clearance of sildenafil were lower in pregnant rabbits [32.1 versus 12.2 L, 110 versus 44.4 L and 25.5 versus 12.1 L/h; all p < 0.05]. The formation clearance from sildenafil to desmethylsildenafil was also reduced during pregnancy [13.3 versus 7.8 L/h; p < 0.05].3. In contrast, the elimination clearance of desmethylsildenafil, was higher in pregnancy [73.5 versus 116. 9; p < 0.05]. In rabbits, pregnancy impacts PK parameters of sildenafil and its metabolite, leading to an increased peak concentration and 24 h exposure for sildenafil and a decreased 24 h exposure for desmethylsildenafil.