Wistar Rat Pups Research Articles

A transient insulin system dysfunction in newborn rat brain followed by neonatal intracerebroventricular administration of streptozotocin could be accompanied by a labile cognitive impairment

The early postnatal period is a critical period of hippocampus development, which is highly dependent on insulin receptor (IR) signaling and very important in cognitive function. The present study was conducted in order to present a model of neonatal transient brain insulin system dysfunction through finding an appropriate dose of injection of streptozotocin (STZ) during the neonatal period.Sixty male Wistar rat pups were divided into 4 groups of 15 and received intracerebroventricular saline or STZ (icv-STZ) (15, 20 and 25μg/kg) on postnatal day 7. Gene expression of IR and target genes for IR signaling (choline acetyltransferase (ChAT) and Tau) were measured at the ages of 2 and 7 weeks. Behavioral tests were performed at the ages of 3 and 6 weeks to assess short- and long-term cognitive function. 20μg/kg dose of icv-STZ was estimated as the optimal dose causing transient alteration in gene expression of IR, ChAT and Tau. Additionally, cognitive function of the animals restored to normal level at the age of 6 weeks. Therefore, 20μg/kg dose of icv-STZ is proposed as a new approach to generating transient brain insulin system dysfunction associated with transient cognitive impairments at a critical postnatal period of brain development.

Morphine exposure and maternal deprivation during the early postnatal period alter neuromotor development and nerve growth factor levels

The objective of this study was to verify whether repeated morphine administration and maternal deprivation in early life alter neurobehavioral development and central nerve growth factor (NGF) levels. A total of 58 male Wistar rat pups were used in our study. From postnatal day 1 (P1), litters were daily deprived of their mother for 3h; this was continued for the first 10days of life. Animals were divided into 5 groups: total control (C), did not receive any intervention; saline (S), received saline solution; morphine (M), received morphine; deprived-saline group (DS), were subjected to maternal deprivation and received saline solution; and deprived-morphine (DM), were subjected to maternal deprivation and received morphine. From P8, newborns received subcutaneous (s.c.) injections of morphine or saline (5μg) once daily for 7days. Righting reflex, negative geotaxis and gait were chosen as postural parameters to evaluate neuromotor reflexes. In the righting reflex test, a delay in the development of animals was evidenced in the M group. Performance of negative geotaxis was slower in the M and DM groups. In the gait test, all groups showed a daily improvement in performance in terms of locomotion frequency. An increased frequency of rearing was observed in the M, DS, and DM groups from P16 to P20. The DM group presented an increase in NGF levels in the brainstem. An increase in cerebral cortex NGF levels in the M, DS, and DM groups was observed as well. Our results suggest that changes in environmental conditions and the disruption of mother–infant interactions during the neonatal period can produce changes in the neurobiology, physiology, and emotional behavior of rats. This finding has important implications for the maternal-neonate interaction needed for normal brain development in newborns.

Prevention of selenite‐induced cataractogenesis by sildenafil in rats

PurposeTo evaluate the effect of sildenafil on selenite‐induced cataract formation in a rat model.MethodsTwenty‐six Wistar rat pups were divided into four groups. Seven pups received only selenite on postpartum day 10 (group 1), 7 pups received selenite and additional high dose sildenafil on postpartum day 10 (group 2), 6 pups received selenite and additional low dose sildenafil on postpartum day 10 (group 3), and 6 pups received only saline (group 4, control). All pups were examined for the presence of cataract under the microscope, starting from the day their eyes opened. Nitrite oxide metabolites, advanced oxidation protein products and total sulfhydryl levels were evaluated in both serum and lenticular samples.ResultsIn group 3, the extent of lens opacification was significantly less than that of selenite‐injected untreated rats (group 1) (p < 0.05). None of the rats in group 4 developed any lens opacity. In lenticular samples, nitrite oxide metabolites level was statistically lower in group 3 compared to group 1 (p < 0.05). In serum, advanced oxidation protein products and total sulfhydryl levels was statistically lower in group 3 compared to group 1 (p < 0.05).ConclusionsLow dose sildenafil appears to inhibit selenite‐induced cataractogenesis in the rat model, and this seems to be caused by the prevention of oxidative damage.

Perinatal Brain Docosahexaenoic Acid Concentration Has a Lasting Impact on Cognition in Mice

Background: Vitamin D deficiency is a global problem. Recent evidence suggests that vitamin D is involved in brain development and function. Vitamin D deficiency has been associated with poor cognitive function in adults, but the effect of developmental vitamin D deficiency (DVDD) on cognitive function and brain development in children has not been well established.Objective: We explored the effects of DVDD on cognitive functions and brain morphology of rat pups.Methods: Wistar rat pups born to control and vitamin D-deficient dams were divided into 4 groups: control (C), deficient during gestation (dG), deficient during lactation (dL), and deficient during gestation and lactation (dGL). Spatial learning and memory were assessed by the Morris water maze test at postnatal day (PND) 24 and PND 45. Cortical thickness at the level of the hippocampus was measured at PND 63, and synapses were counted in specified areas of the hippocampus at PND 32 and PND 63.Results: Repeated-measures ANOVA revealed that at PND 24, learning (escape latency) was impaired (by 42%) in the dGL group, whereas at PND 45, both the dL and the dGL groups showed learning impairment (by 47% and 45%, respectively) compared with their respective C groups (P < 0.05). Short-term or long-term memory was largely unaffected by DVDD either at PND 24 or PND 45. Compared with the C group, all the DVDD groups had fewer synapses in the molecular layer of the hippocampus (P < 0.001). The synapse number decreased by 54% in the dGL group at PND 33 and by 70% in the dL and dGL groups at PND 63. All the DVDD groups at PND 63 showed a reduced cortical thickness (by 22%) compared with the C group (P < 0.05).Conclusion: These results suggest that a combined prenatal and postnatal DVDD for ≥6 wk in rat pups affects learning but not memory.

Experimental neonatal hypoxia ischemia causes long lasting changes of oxidative stress parameters in the hippocampus and the spleen.

Neonatal hypoxia ischemia (HI) is the main cause of mortality and morbidity in newborns. The mechanisms involved in its progression start immediately and persist for several days. Oxidative stress and inflammation are determinant factors of the severity of the final lesion. The spleen plays a major part in the inflammatory response to HI. This study assessed the temporal progression of HI-induced alterations in oxidative stress parameters in the hippocampus, the most affected brain structure, and in the spleen. HI was induced in Wistar rat pups in post-natal day 7. Production of reactive oxygen species (ROS), and the activity of the anti oxidant enzyme superoxide dismutase and catalase were assessed 24 h, 96 h and 38 days post-HI. Interestingly, both structures showed a similar pattern, with few alterations in the production of ROS species up to 96 h often combined with an increased activity of the anti oxidant enzymes. However, 38 days after the injury, ROS were at the highest in both structures, coupled with a decrease in the activity of the enzymes. Altogether, present results suggest that HI causes long lasting alterations in the hippocampus as well as in the spleen, suggesting a possible target for delayed treatments for HI.

Bone Morphogenetic Protein 9 Protects against Neonatal Hyperoxia-Induced Impairment of Alveolarization and Pulmonary Inflammation.

Aim: Effective treatment of premature infants with bronchopulmonary dysplasia (BPD) is lacking. We hypothesize that bone morphogenetic protein 9 (BMP9), a ligand of the TGF-β family that binds to the activin receptor-like kinase 1 (ALK1)-BMP receptor type 2 (BMPR2) receptor complex, may be a novel therapeutic option for BPD. Therefore, we investigated the cardiopulmonary effects of BMP9 in neonatal Wistar rats with hyperoxia-induced BPD.Methods: Directly after birth Wistar rat pups were exposed to 100% oxygen for 10 days. From day 2 rat pups received BMP9 (2.5 μg/kg, twice a day) or 0.9% NaCl by subcutaneous injection. Beneficial effects of BMP9 on aberrant alveolar development, lung inflammation and fibrosis, and right ventricular hypertrophy (RVH) were investigated by morphometric analysis and cytokine production. In addition, differential mRNA expression of BMP9 and its receptor complex: ALK1, BMPR2, and Endoglin, and of the ALK1 downstream target transmembrane protein 100 (TMEM100) were studied during the development of experimental BPD. Expression of the BMP9 receptor complex and TMEM100 was studied in human endothelial and epithelial cell cultures and the effect of BMP9 on inflammatory cytokine production and TMEM100 expression was studied in endothelial cell cultures.Results: ALK1, ALK2, BMPRII, TMEM100, and Endoglin were differentially expressed in experimental BPD, suggesting a role for BMP9-dependent signaling in the development of (experimental) BPD. TMEM100 was expressed in the wall of blood vessels, showing an elastin-like expression pattern in arterioles. Expression of TMEM100 mRNA and protein was decreased after exposure to hyperoxia. BMP9 treatment of rat pups with hyperoxia-induced experimental BPD reduced alveolar enlargement, lung septal thickness and fibrosis, and prevented inflammation, but did not attenuate vascular remodeling and RVH. The anti-inflammatory effect of BMP9 was confirmed in vitro. Highest expression of ALK1, BMPR2, and TMEM100 was observed in human endothelial cell cultures. Stimulation of human endothelial cell cultures with BMP9 reduced their pro-inflammatory cytokine response and induced TMEM100 expression in pulmonary arterial endothelial cells.Conclusion: BMP9 protects against neonatal hyperoxia-induced BPD by improving aberrant alveolar development, inflammation and fibrosis, demonstrating its therapeutic potential for premature infants with severe BPD.

Prevention and reversal of selenite-induced cataracts by N-acetylcysteine amide in Wistar rats

BackgroundThe present study sought to evaluate the efficacy of N-acetylcysteine amide (NACA) eye drops in reversing the cataract formation induced by sodium selenite in male Wistar rat pups.MethodsForty male Wistar rat pups were randomly divided into a control group, an N-acetylcysteine amide-only group, a sodium selenite-induced cataract group, and a NACA-treated sodium selenite-induced cataract group. Sodium selenite was injected intraperitoneally on postpartum day 10, whereas N-acetylcysteine amide was injected intraperitoneally on postpartum days 9, 11, and 13 in the respective groups. Cataracts were evaluated at the end of week 2 (postpartum day 14) when the rat pups opened their eyes. N-acetylcysteine amide eye drops were administered beginning on week 3 until the end of week 4 (postpartum days 15 to 30), and the rats were sacrificed at the end of week 4. Lenses were isolated and examined for oxidative stress parameters such as glutathione, lipid peroxidation, and calcium levels along with the glutathione reductase and thioltransferase enzyme activities. Casein zymography and Western blot of m-calpain were performed using the water soluble fraction of lens proteins.ResultsMorphological examination of the lenses in the NACA-treated group indicated that NACA was able to reverse the cataract grade. In addition, glutathione level, thioltransferase activity, m-calpain activity, and m-calpain level (as assessed by Western blot) were all significantly higher in the NACA-treated group than in the sodium selenite-induced cataract group. Furthermore, sodium selenite- injected rat pups had significantly higher levels of malondialdehyde, glutathione reductase enzyme activity, and calcium levels, which were reduced to control levels upon treatment with NACA.ConclusionsThe data suggest that NACA has the potential to significantly improve vision and decrease the burden of cataract-related loss of function. Prevention and reversal of cataract formation could have a global impact. Development of pharmacological agents like NACA may eventually prevent cataract formation in high-risk populations and may prevent progression of early-stage cataracts. This brings a paradigm shift from expensive surgical treatment of cataracts to relatively inexpensive prevention of vision loss.

Quercetin Reverses the Enhanced Contractile Responses of Tracheal Smooth Muscle of Neonatal Rats Exposed to Hyperoxia

Neonatal hyperoxia increases contraction and decreases the relaxation of airway smooth muscle (ASM), and the balance between these processes in airways is critical for normal flow of air. Thus, it is important to search for an effective treatment to prevent the airway hyperreactivity. Therefore, we tested the hypothesis that supplementation of quercetin will overcome the enchanced contractile responses of tracheal smooth muscle exposed to hyperoxia. Tracheal cylinders were obtained from Wistar rat pups (P12) exposed to hyperoxia (≥ 95% O2) or room air for seven days. These cylinders were used to study contractile responses of ASM evoked by methacholine (MCh, 10‐8 – 10‐4 M) in absence or presence of quercetin (100 μM). MCh induced dose‐dependent contractile responses of ASM. Hyperoxic exposure significantly increased the contractile responses of ASM towards MCh, as compared to those obtained from control animals exposed to room air, and these enhanced contractile responses in hyperoxic tissues were significantly attenuated in presence of quercetin. The results of this study revealed that quercetin reverses the enhanced contractile responses of airway smooth muscle induced by hyperoxic exposure and we speculate that the use of quercetin might be an effective therapeutic approach to prevent the airway hyperreactivity induced by hyperoxia.Support or Funding InformationSupported by MEST

Role of PGE2‐EP1/EP3 receptor signaling on hyperoxia‐induced airway hyperreactivity in neonatal rats

Hyperoxic exposure of neonates is followed by airway hyperreactivity, that involves many different molecular signaling mechanisms, including PGE2/EP‐receptor signaling. The aim of this study was to investigate the role of EP1/EP3 receptors on airway hyperreactivity in neonatal rats exposed to hyperoxia. Tracheal cylinders were obtained from Wistar rat pups (P12) exposed for seven days to hyperoxia or room air. The preparations were used to study contractile responses in an in vitro organ bath system. In hyperoxic group the contractile responses significantly were enhanced towards a muscarinic agonist (methacholine) as compared to room air control group. Pre‐incubation of tissues on EP1/EP3 antagonists, significantly reduced these enhanced responses in hyperoxic group. Use of EP1/EP3 agonists and Rho‐kinase inhibitors disclosed the involvement of Rho‐kinase pathway on the signaling of EP1/EP3 receptors. The results of this study for the first time confirm the contribution of the EP1/EP3 receptors on hyperoxia‐induced airway hyperreactivity and the involvement of Rho‐kinase pathway. We suggest the use of EP1or EP3 antagonists or Rho‐kinase inhibitors as a therapy parallel to hyperoxic exposure in order to overcome the adverse effects of neonatal hyperoxia and to prevent the development of bronchopulmonary dysplasia as consequence of hyperoxic exposure.Support or Funding InformationSupported by MEST

Resveratrol Protects Against Hyperoxia‐Induced Airway Hyperreactivity in Neonatal Rats

Neonatal hyperoxia is associated with airway hyperreactivity and lung injury. We tested the hypothesis that supplementation of resveratrol will overcome the increased contractile responses of tracheal smooth muscle exposed to hyperoxia. Tracheal cylinders were obtained from Wistar rat pups (P12) exposed to hyperoxia (≥ 95% O2) or room air for seven days. These cylinders were used to study contractile responses of airway smooth muscle (ASM) evoked by methacholine (MCh, 10‐8 – 10‐4 M) in absence or presence of resveratrol (100 μM). MCh induced dose‐dependent contractile responses of ASM. The contractile responses towards MCh were significantly higher in preparations obtained from animals exposed to hyperoxia as compared to those obtained from control animals exposed to room air. The enhanced contractile responses in hyperoxic tissues were significantly attenuated in presence of resveratrol. The results of this study revealed that resveratrol diminishes the airway hyperreactivity induced by hyperoxia and we speculate that the use of resveratrol might be an effective therapeutic approach to prevent the adverse effects of hyperoxia.Support or Funding InformationSupported by MEST

Behavioral improvements in a valproic acid rat model of autism following vitamin D supplementation

The aim was to identify the effects of early vitamin D supplementation on autism-like behaviors (ASD) induced by valproic acid (VPA, an anti-convulsant and a mood stabilizer) in rats. 10 male Wistar rat pups with prenatal exposure to saline were in control group, and 20 Pups with prenatal exposure to VPA were divided into ASD-N (0.9% saline treated) and ASD-D group (vitamin D 80,000 IU/kg treated) on postnatal day 12. Self-grooming, olfactory habituation/dishabituation, and social interaction tests were conducted to assess social interaction, communication, and repetitive behaviors. Serum 25-hydroxyvitamin D (25(OH)D3) was measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results showed that compared with the control group, the ASD-N group exhibited increased self-grooming, and decreased pinning and serum 25(OH)D3. Furthermore, the repetitive behavior of the ASD-N group exhibited a negative linear relationship with serum 25(OH)D3 on PND 42. In conclusion, early vitamin D supplementation in infant rat with ASD induced by VPA significantly improved development and behavior of rats related with ASD.

Effects of early life stress and adolescent ethanol exposure on adult cognitive performance in the 5-choice serial reaction time task in Wistar male rats.

Early life stress combined with heavy adolescent alcohol use predicts impaired neuropsychological functioning in adulthood. We investigated whether adolescent intermittent ethanol (AIE) exposure combined with neonatal maternal separation in rats altered attentional processes and impulsivity in adulthood. Male Wistar rat pups were exposed to maternal separation (postnatal days (PNDs) 1-14) and moderate AIE exposure (PNDs 28-57). Adult rats were tested in the five-choice serial reaction time task, which provides separate measures of attention, motor impulsivity, and compulsivity. Rats were tested under baseline conditions and in response to task manipulations that increased attentional load and impulsive behaviors, and after acute ethanol administration. Short stimulus and short intertrial interval (ITI) durations disrupted attention while long ITI durations impaired impulsivity in all rats. Moderate- and high-dose ethanol challenges impaired attention in all rats. Rats exposed to maternal separation and/or AIE exposure had significantly decreased omissions than non-handled water-exposed rats at baseline and tended to retain this effect in response to task challenges (i.e., the shorter stimulus and ITI durations, longer test session) and ethanol challenges, indicating moderate improvement of attentional performance. Maternal separation significantly increased perseverative responses at baseline and in response to decreased stimulus duration challenge, suggesting increased compulsivity. Separate or combined exposure to early life stress and AIE exposure moderately disrupts some aspects of adult executive control functions (e.g., increased compulsivity) but improves others (e.g., increased attention). The relative intensity of either manipulation during neonatal and adolescent periods may influence the direction in which cognitive behaviors are affected in adulthood.

Effect of Aqueous Extract of Kola nitida on the Development of Biliary Atresia in Pups of Wistar Rats

Effect of Aqueous Extract of Kola nitida on the Development of Biliary Atresia in Pups of Wistar Rats

Intervention with the mother-infant relationship reduces cell proliferation in the Locus Coeruleus of female rat pups.

The Locus Coeruleus (LC) is a noradrenergic nucleus involved in several neuroendocrine and behavioral functions. During the neonatal period, the LC is critical for olfactory learning. Full development occurs during the early postnatal period. Environmental interventions after birth may affect neurogenesis. In rats, the neonatal handling procedure has been used as a model to analyze the effects of environmental intervention early in life. It has been related to several long-lasting behavioral and neuroendocrine changes. The present study analyzed the effects of handling on the number of neurons, cellular proliferation, and apoptosis in the LC of 11-day-old female rats. Wistar rat pups were submitted to brief maternal separation followed by handling (1 min per day from postnatal day [PND] 1 to 10). On PND 11, the LC was analyzed using immunohistochemistry for NeuN and BrdU, TUNEL staining, and electron microscopy. The intervention reduced the number of neurons in the LC but showed no significant change in the number of apoptotic cells, as measured by the TUNEL technique. However, the number of proliferating cells was significantly lower in the handled rat pups as compared with the nonhandled ones. This study demonstrates that the infant LC is sensitive to changes in maternal behavior. A seemingly mild environmental intervention during the neonatal period may reprogram the development of the LC, altering cell proliferation. (PsycINFO Database Record

Testicular Changes in Male Albino Rat Pups Exposed to Medroxy- Progesterone Acetate during Lactational Period

There are great concerns regarding the use of synthetic progesterone during breastfeeding due to probable negative effects on future fecundity of male infants. Therefore the present study was conducted to evaluate the effects of exposing male rat pups to depot medroxyprogesterone acetate (DMPA) during lactational period on pubertal testicular histology, morphometry and cells quantitation. Twenty male Wistar rat pups reared to dams treated with DMPA (10 mg/ kg BW) every other day during their early lactation period; were employed to achieve the objectives of this study. Other 20 male rat pups reared to untreated dams served as control. The pups were allowed to reach 90 days old, sacrificed, their testes were dissected and weighed and histological sections were prepared. The results showed that exposing male rat pups to DMPA during the lactational period significantly (P<0.001) affected their testicular histology, morphometry and the quantities of testicular cells. The thickness of the germinal epithelium (GE) and the diameter of the seminiferous tubules (ST) were reduced; while the interstitial space (IS) thicknesses were increased. The testicular cells of the rats reared on dams treated with DMPA experienced varying degrees of apoptosis and count reduction. The ST appeared with unusual configuration with detached and/or folded basal lamina, it has few germinal layers, decreased Sertoli cells (SC) and their lumen contained cells debris and very few sperms; while the wide IS contained few Leydig cells (LC). Exposure to DMPA during the lactational period adversely affects the testicular structure. Thus foretells a negative impact on future fertility.

Administration of Huperzia quadrifariata Extract, a Cholinesterase Inhibitory Alkaloid Mixture, has Neuroprotective Effects in a Rat Model of Cerebral Hypoxia-Ischemia.

Neonatal hypoxia-ischemia (HI) is an etiologic component of several neurologic pathologies associated to cognitive impairment. The mechanisms involved in HI-induced tissue damage start immediately after HI and extend for days. Acetylcholine is an important neurotransmitter in the central nervous system and exerts a protector effect on tissue damage by modulating inflammation, and cholinesterase inhibitors have shown neuroprotective properties and their action are often attributed to inhibition of the immune response. The administration of Huperzia quadrifariata alkaloid extract (HqAE), with potent and selective cholinesterase inhibitor properties, will reduce the HI induced behavioral deficits and tissue damage. A total of 84 newborn Wistar rat pups at post natal day 7 (PND7) were subjected to right carotid occlusion followed by 1h of hypoxia (8% of O2) and i.p. injections of saline, vehicle or HqAE (10mg/kg). Morris Water Maze and inhibitory avoidance tests were used to assess the cognitive function. Flow cytometry was performed at PND11. Histological analysis was performed at PND45. HqAE treatment was able to prevent the HI induced cognitive deficits in both tests and, at PND45, histological analysis showed that HqAE treatment reduced hippocampus tissue damage. Flow cytometry of the injured hippocampus revealed that the treatment was able to reduce cellular death and the number of infiltrating T cells. Altogether, these results show the therapeutic potential of the Huperzia quadrifariata alkaloid extract to prevent cognitive deficits and histological damage caused by neonatal hypoxia-ischemia, probably by reducing cellular death and T cell mobilization.

Longer hypoxia–ischemia periods to neonatal rats causes motor impairments and muscular changes

Prematurity and hypoxia–ischemia (HI) can lead to movement disorders in infants. Considering that mild-moderate HI induced at postnatal day (PND) 3 has failed to produce motor disabilities similar to those seen in pre-term newborns, the main goal of the present study was to verify whether longer hypoxia periods would mimic motor function impairment, brain and muscle morphological alterations. Forty-nine Wistar rat pups of both sexes were randomly assigned to surgical control (CG) and HI groups. HI animals were submitted to the Levine-Rice model at PND 3, and exposed to 120 (HI-120′), 180 (HI-180′) or 210 (HI-210′) minutes of hypoxia (FiO2: 0.08). Sensorimotor function was assessed as from PND 35–45, by means of grasping strength, adhesive removal, cylinder and ladder walking tests. Histological staining was used to quantify the striatal volume and the cross-sectional area (CSA) of skeletal muscles. Cylinder and adhesive removal test evidenced that HI-180′ and HI-210′ groups had asymmetrical use of the forepaws when compared to controls. HI animals showed a decrease in the step placement quality and an increase in step errors when compared to CG (P⩽0.05). Reduction in striatal volume correlates with behavioral assessment, HI-180′ and HI-210′ groups presented lower biceps brachii and tibialis anterior CSA. These results show that rats exposed to longer hypoxic periods at PND3 have encephalic and sensorimotor impairments that mimic those observed in preterm infants. Morphological changes in muscle tissue evidence a new pathophysiological characteristic of the HI model that might be of relevance for the study of sensorimotor deficits.

156 - A Dual Therapeutic Approach for the Reversal of Cataracts

Over 20 million people suffer from cataracts worldwide. Currently, surgery is the only effective treatment for this condition. Although cataract surgery is routine and generally considered safe, it is neither feasible nor accessible for much of the world's population, especially in developing countries where surgeons are few and access to facilities is limited. Thus there is a high demand for an effective, topical treatment that can reverse or prevent cataracts in those for whom surgery is not a viable option. Cataract is a clouding of the lens caused by the aggregation of water-soluble proteins known as crystallins. These crystallin proteins are a major component of the lens and are responsible for its ability to refract light. Crystallin proteins are rich in sulfur-containing amino acids, and are thus susceptible to the formation of disulfide bonds upon oxidative damage. This damage results in protein misfolding and aggregation. Thiol antioxidants have the potential to protect these proteins from oxidative damage and to prevent the formation of cataracts. α-Crystallins act as chaperones for other crystallin isoforms, binding damaged β- and γ-crystallins and impeding aggregation. Recently, sterols such as lanosterol and 25-hydroxycholesterol have demonstrated the ability to stabilize the healthy, functional α-crystallin structure, preserving the function of these chaperones. The primary objective of the following studies was to target crystallin aggregation both directly (through use of a thiol antioxidant to reduce oxidized crystallins) and indirectly (by bolstering α-crystallin stability). To investigate promising thiol antioxidant candidates for incorporation into a topical cataract treatment, HPLC analysis was conducted on topically treated male Wistar rat pup lenses to determine the bioavailability of various thiols. Selected thiol antioxidants were examined for their ability to reverse cataracts when used in combination with 25-hydroxycholesterol.

Prevention and reversal of selenite‐induced cataracts by N‐acetylcysteine amide in Wistar rats

PurposeThe present study sought to evaluate the efficacy of N‐acetylcysteine amide (NACA) eye drops in reversing the cataract formation induced by sodium selenite in male Wistar rat pups.MethodsForty male Wistar rat pups were randomly divided into treatment groups. Cataracts were evaluated at the end of week 2 (postpartum day 14) when the rat pups opened their eyes. NACA eye drops were administered beginning week 3 till the end of week 4 (postpartum days 15–30) and the rats were sacrificed at the end of week 4. Lenses were isolated and examined for oxidative stress parameters such as glutathione, lipid peroxidation, and calcium levels along with the glutathione reductase and thioltransferase enzyme activities. Casein zymography and Western blot of m‐calpain were performed using water soluble fraction of lens proteins.ResultsMorphological examination of the lenses in the NACA‐treated group indicated that NACA was able to reverse the cataract grade. In addition, glutathione (GSH) level, thioltransferase (Ttase) activity, m‐calpain activity, and m‐calpain level (as assessed by Western blot) were all significantly higher in the NACA‐treated group than in the Na2SeO3‐induced cataract group. Furthermore, sodium selenite injected rat pups had significantly higher levels of malondialdehyde (MDA), glutathione reductase (GR) enzyme activity, and calcium levels, which were reduced to control levels upon treatment with NACA.ConclusionsNACA has the potential to significantly improve patient health and the clinical care of cataracts. Further development of pharmacological agents like NACA may eventually help ophthalmologists prevent cataract formation in high‐risk populations and non‐surgically treat early stage cataracts, producing favorable patient outcomes while decreasing medical costs.

A dual therapeutic approach for the reversal of cataracts

PurposeOver 20 million people suffer from cataracts worldwide. Currently, surgery is the only effective treatment for this condition. Although cataract surgery is routine and generally considered safe, it is neither feasible nor accessible for much of the world's population. Thus, there is a high demand for an effective topical treatment that can reverse or prevent cataracts in those for whom surgery is not a viable option. Clouding of the lens is caused by the aggregation of water‐soluble crystallin proteins. Crystallins are a major component of the lens and allow it to refract light. Crystallins are rich in sulfur‐containing amino acids, which are susceptible to the formation of disulfide bonds upon oxidative damage. This damage results in protein misfolding and aggregation. Thiol antioxidants have the potential to protect these proteins from oxidative damage and to prevent the formation of cataracts. α‐Crystallins act as chaperons for other crystallin isoforms, binding damaged β‐ and γ‐crystallins and impeding aggregation. Recently, sterols such as lanosterol and 25‐hydroxycholesterol have demonstrated the ability to stabilize the healthy, functional α‐crystallin structure, which preserves the anti‐aggregation action of these chaperons. The objective of this study was to determine additive and/or synergistic effects of a thiol antioxidant in combination with 25‐hydroxycholesterol to combat crystallin aggregation in two ways: protecting crystallin thiol residues and bolstering α‐crystallin chaperon activity.MethodsTo investigate thiol antioxidant candidates for incorporation into a topical cataract treatment, an ex vivo model using Wistar rat pup lenses was employed. Various thiol antioxidants were examined for their ability to reverse cataracts when used in combination with 25‐hydroxycholesterol.ResultsTo be discussed.ConclusionsTo be discussed.