Regulation of MicroRNAs.

MicroRNAs are RNAs of about 18-24 nucleotides in lengths, which are found in the small noncoding RNA class and have a crucial role in the posttranscriptional regulation of gene expression, cellular metabolic pathways, and developmental events. These small but essential molecules are first processed by Drosha and DGCR8 in the nucleus and then released into the cytoplasm, where they cleaved by Dicer to form the miRNA duplex. These duplexes are bound by the Argonaute (AGO) protein to form the RNA-induced silencing complex (RISC) in a process called RISC loading. Transcription of miRNAs, processing with Drosha and DGCR8 in the nucleus, cleavage by Dicer, binding to AGO proteins and forming RISC are the most critical steps in miRNA biogenesis. Additional molecules involved in biogenesis at these stages can enhance or inhibit these processes, which can radically change the fate of the cell. Biogenesis is regulated by many checkpoints at every step, primarily at the transcriptional level, in the nucleus, cytoplasm, with RNA regulation, RISC loading, miRNA strand selection, RNA methylation/uridylation, and turnover rate. Moreover, in recent years, different regulation mechanisms have been discovered in noncanonical Drosha or Dicer-independent pathways. This chapter seeks answers to how miRNA biogenesis and function are regulated through both canonical and non-canonical pathways.

44 Current Challenges in miRNomics.

Mature microRNAs (miRNAs) are short RNA sequences about 18-24 nucleotide long, which provide the recognition key within RISC for the posttranscriptional regulation of target RNAs. Considering the canonical pathway, mature miRNAs are produced via a multistep process. Their transcription (pri-miRNAs) and first processing step via the microprocessor complex (pre-miRNAs) occur in the nucleus. Then they are exported into the cytosol, processed again by Dicer (dsRNA) and finally a single strand (mature miRNA) is incorporated into RISC (miRISC). The sequence of the incorporated miRNA provides the function of RNA target recognition via hybridization. Following binding of the target, the mRNA is either degraded or translation is inhibited, which ultimately leads to less protein production. Conversely, it has been shown that binding within the 5' UTR of the mRNA can lead to an increase in protein product. Regulation of homeostasis is very important for a cell; therefore, all steps in the miRNA-based regulation pathway, from transcription to the incorporation of the mature miRNA into RISC, are under tight control. While much research effort has been exerted in this area, the knowledgebase is not sufficient for accurately modelling miRNA regulation computationally. The computational prediction of miRNAs is, however, necessary because it is not feasible to investigate all possible pairs of a miRNA and its target, let alone miRNAs and their targets. We here point out open challenges important for computational modelling or for our general understanding of miRNA-based regulation and show how their investigation is beneficial. It is our hope that this collection of challenges will lead to their resolution in the near future.

Transcriptome Dynamics of Human Neuronal Differentiation From iPSC.

The generation and use of induced pluripotent stem cells (iPSCs) in order to obtain all differentiated adult cell morphologies without requiring embryonic stem cells is one of the most important discoveries in molecular biology. Among the uses of iPSCs is the generation of neuron cells and organoids to study the biological cues underlying neuronal and brain development, in addition to neurological diseases. These iPSC-derived neuronal differentiation models allow us to examine the gene regulatory factors involved in such processes. Among these regulatory factors are long non-coding RNAs (lncRNAs), genes that are transcribed from the genome and have key biological functions in establishing phenotypes, but are frequently not included in studies focusing on protein coding genes. Here, we provide a comprehensive analysis and overview of the coding and non-coding transcriptome during multiple stages of the iPSC-derived neuronal differentiation process using RNA-seq. We identify previously unannotated lncRNAs via genome-guided de novo transcriptome assembly, and the distinct characteristics of the transcriptome during each stage, including differentially expressed and stage specific genes. We further identify key genes of the human neuronal differentiation network, representing novel candidates likely to have critical roles in neurogenesis using coexpression network analysis. Our findings provide a valuable resource for future studies on neuronal differentiation.

The role of microRNAs in corneal neovascularization and its relation to VEGF.

PURPOSE: This study aimed to investigate the changes in the level of miRNA associated with Vascular Endothelial Growth Factor (VEGF) in corneal neovascularization (CNV), to elucidate the process of CNV formation and, thus, to prepare the ground for further experimental, and clinical studies together with drug treatments. METHODS: Twelve male Wistar-Albino rats were randomly divided into two groups of six, and two corneas of each rat were used. In all groups, CNV was generated by silver nitrate sticks. At the end of the study, rats were sacrificed by cervical dislocation under ether anaesthesia, and then, their corneas were removed. The expression levels of VEGF and miRNA in corneas were determined by qRT-PCR array and qRT-PCR. Data analysis was performed using web-based software named PCR array data. RESULTS: When the corneal samples of rats with CNV were compared to those of the control rats, it was found that a statistically significant difference was present regarding the VEGF level (p < 0.05) with the fold-regulation value> 2. According to the under- and over-expression data in miRNA PCR Array findings of both groups, statistically significant differences were found regarding nine genes with Fold-regulation value <-2 and Fold-regulation value> 2 (p < 0.05). When the corneal samples of the rats with CNV were compared to those of the control rats, statistically significant over-expressions (Fold-regulation value> 2) of rno-miR-21_2, rno-miR-126_1 and rno-miR-150_1 genes were found (p = 0.002443, p = 0.030146, p = 0.000348, respectively). In the same comparison, rno-miR-184_1 gene showed statistically significant under-expression with a Fold-regulation value <-2 (p = 0.006428). Also, in the comparison of the two groups, the fold regulation value of the rno-miR-31_1 gene was found to be close to - g and statistically significantly under-expressed (p = 0.005082). CONCLUSION: The over-expressions of rno-miR-21_2, rno-miR-126_1, and rno-miR-150_1 genes, and the under-expression of rno-miR-184_1 gene were thought to could play roles in the formation process of CNV by regulation of VEGF-A and through modulation of angiogenesis.

Effect of experimentally induced hypothyroidism during gestation period on activity dependent neurotrophic factor (ADNF) in newborn rat brain tissue.

Purpose The aim of the study was to evaluate the effects of prenatal hypothyroidism on neonatal rats by the way of activity-dependent neuroprotective factor (ADNF) expression. Methods Twenty-one Wistar albino neonatal rats were divided into two subgroups; a control group and neonatal rats with experimental maternal hypothyroidism. Hypothyroidism was induced by using propylthiouracil (PTU). Neonatal rats obtained PTU from breast milk continuously for 1 week after birth. The rats from the control group were fed only normal feed and water. After birth, body weight and blood thyroid hormone levels were tested. Glial fibrillary acidic protein (GFAP), Slug, Numb, Notch-1 and ADNF antibodies were used for immunohistochemical analysis. Real-time polymerase chain reaction (RT-PCR) and Western blotting analyses were used to evaluate ADNF gene expression levels from 1-week-old rat's brain. Results There was no difference between the two groups for birth weights. The thyroxine (T4) level from the experimental group was <0.4 ng/mL, and it was 0.8 ng/mL for the control group. It was shown that, the results from the experimental group samples had significantly lower ADNF mRNA levels than control group (p < 0.05). The increase from GFAP and Numb expression and decrease from Slug expression were shown in the experimental group. Local differences were identified for ADNF and a decrease was shown in both sides of brain. There was no difference for Notch-1 expression for both groups. Conclusion In this study, decreasing ADNF expression might contribute to developing neurological problems in congenital hypothyroidism.

Effects of sunitinib and bevacizumab on VEGF and miRNA levels on corneal neovascularization.

AIM: To evaluate the effects of sunitinib (0.5 mg/ml) and bevacizumab (5 mg/ml) on VEGF-A, VEGFR-2 and microRNA (miRNA) levels on corneal neovascularization (CNV). METHODS: In this study, CNV was induced by silver nitrate application to the cornea, and 40 Albino male rats were equally divided into four subgroups: Group 1 (sunitinib): After silver nitrate application to the cornea, 0.5 mg/ml sunitinib eyedrop was administered twice daily for two weeks (n = 10). Group 2 (bevacizumab): After silver nitrate application to the cornea, 5 mg/ml bevacizumab eyedrop was administered twice daily for two weeks (n = 10). Group 3 (control): After silver nitrate application to the cornea, normal saline eyedrop was administered twice daily for two weeks (n = 10). Group 4 (vehicle): After silver nitrate application to the cornea, 1% DMSO eyedrop was administered twice daily for two weeks (n = 10). After two weeks from the silver nitrate application, corneas were evaluated by hand-held biomicroscope for their vascularization status. Then, corneas were excised and the expression levels of VEGFR-2, VEGF-A and the common miRNA markers for neovascularization (miR-15 b, miR-16, miR-23a, miR-126, miR-188, miR-210, miR-221, miR-222, miR-410 and miR-423) were evaluated by real-time PCR. RESULTS: It was seen that the CNV was decreased in sunitinib- and bevacizumab-administered groups compared to the control and DMSO groups. Also, in comparison with the control group; VEGF-A expression was downregulated by nearly 0.75 times in sunitinib group and nearly 0.52 times in bevacizumab group. VEGFR-2 expression was downregulated by 0.89 times in sunitinib group and 0.68 times in bevacizumab group, compared to the control group. miR-15 b, miR-16 and miR-126 levels were statistically lower in sunitinib and bevacizumab groups, but miR-188 and miR-410 levels were two-fold higher compared to the control group. The miR-210 level was found higher only in sunitinib group compared to the control group. There were no statistically significant changes in miR-23a, miR-221, miR-222 and miR-423 levels among the groups. CONCLUSION: Topical application of bevacizumab (5 mg/ml) and sunitinib (0.5 mg/ml) decreases the levels of VEGFR-2 and VEGF-A in CNV. Further studies are needed for detailed analysis of genes which are targeted by up- or downregulated miRNAs in this study.

MicroRNA profiles in neuroblastoma: Differences in risk and histology groups.

AIM: To determine the miRNA expression profiles of neuroblastomas with different clinical and histological characteristics. METHODS: In this study 24 samples from 17 patients, paraffin blocks were used. Their microRNA profiles were compared by five different analysis: analysis I: well-poorly differentiated, analysis II: before-after chemotherapy, analysis III: favorable-unfavorable histology, analysis IV: neuroblastoma-ganglioneuroma, analysis V: low-risk-middle-risk-high risk groups. Clinical data were compared with differentially expressed microRNAs. RESULTS: It was found that 25 miRNAs between well-poorly differentiated tumors, eight miRNAs before and after of the chemotherapy, three miRNAs between favorable and unfavorable histology, four miRNAs between neuroblastoma and ganglioneuroma, seven miRNAs between low and middle risk, one miRNA between middle and high risk, 14 miRNAs between low and high risk were differently expressed (P < 0.01). These miRNA's targeted mostly the cancer pathway by the KEGG pathway analysis. The most marked difference was seen in miR-132 and miR-490, comparing the clinical data and all microRNAs. The most fold change was detected at miR-98-5p between the tissues of high- and low-risk patients. CONCLUSION: In this study, we represent microRNA expression profiles of neuroblastoma patients' tissue with different clinical, histological grade, differentiation, and treatment status, and which could be informative for new therapies targeting microRNAs.

The effects of topical everolimus and sunitinib on corneal neovascularization.

PURPOSE: To evaluate the effects of topical everolimus and sunitinib on corneal neovascularization (CNV). METHODS: CNV was induced by application of silver nitrate to the cornea for all groups. Rats were divided into four groups of 10 rats each, and two corneas were obtained from each rat. Group I received 1 mg/ml everolimus, Group II received 0.5 mg/ml sunitinib, Group IV received no treatment (control group) and Group IV received 1% Dimethylsulfoxide (DMSO). All treatments were administrated twice daily for 2 weeks. The right corneas were used for extracellular signal-regulated kinase 1/2 (ERK 1/2) protein analysis by western blot analysis and the left corneas were used for ERK 1/2 and vascular endothelial growth factor-receptor (VEGFR-2) gene expression analysis by quantitative real-time PCR. RESULTS: VEGFR-2 mRNA expression levels (ΔCt, median, min-max) were reduced in the everolimus 1.0 (0.25-1.81) and sunitinib 1.06 (0.24-2.68) treated groups compared with the control 4.74 (1.02-14.74) and DMSO groups 7.41 (0.72-13.10). The expression of ERK 1/2 protein and mRNA levels were reduced in everolimus group compared with the control group (p < 0.05). These differences were not seen between the sunitinib and control groups. CONCLUSION: Topical administration of both everolimus and sunitinib reduced VEGFR-2 levels and inhibited CNV. In additon, everolimus reduced ERK 1/2 levels and seems to be more effective than sunitinib on CNV.

The effect of methimazole-induced postnatal hypothyroidism on the retinal maturation and on the Sirtuin 2 level.

PURPOSE: To investigate the effect of methimazole-induced postnatal hypothyroidism on the retinal maturation and to study Sirtuin 2 (SIRT2) level in the hypothyroidic rat retina. METHODS: Twenty newborn Wistar albino rat pups were used in this prospective, randomized study. Wistar albino rats, weight 250-300 g, were impregnated (without addition of any drug) and were fed normally. Rat pups were randomly divided into two groups and were fed with breast milk. After weaning till they were 90 days of age, rat pups received the same water as their lactating mothers drank. Group 1 (methimazole (MMI)-induced hypothyroidy group), rats were given MMI-water, whereas, in Group 2, normal tap water. When the pups were 90 days of age, 20 rat pups were decapitated and the eyes were isolated. Eyes were investigated using histological, histomorphometric and immunohistochemistrical techniques. RESULTS: No histological difference was seen between the groups stained with hematoxylin and eosin. In both groups the retinal layer structures and cells were observed as normal. The examples in the groups had a normal distribution for retinal thickness (pixel) measure. The mean value (mean ± std. deviation) was 554.7 ± 228.4 in the control group and 494.7 ± 129.4 in the hypothyroidy group. There was no significance between the groups in terms of retinal thickness (p = 0.231). However, immunohistochemistry revealed that SIRT2 was weaker stained in the ganglion cell layer and visual cell layer in the hypothyroidy group compared to the control group. CONCLUSION: Postnatal hypothyroidism altered the retinal cytoarchitecture and layering which are regulated by thyroid hormones (THs) during retinal maturation in the postnatal period. THs may act by the induction of the SIRT family proteins or through their receptors. Postnatal screenings for THs levels are very important to provide normal retinal development.

Effect of Resveratrol on Leptin and Sirtuin 2 Expression in the Kidneys in Streptozotocin-induced Diabetic Rats.

OBJECTIVE: To investigate the effect of resveratrol (RSV) on the histopathology and leptin and sirtuin 2 expression levels of the kidneys in streptozotocin (STZ)-induced diabetic rats. STUDY DESIGN: The study was carried out with 33 young, healthy, female Wistar Albino rats. STZ was given (50 mg/kg, intraperitoneal, single dose) to the rats to induce and constitute a diabetes model. After 1 month of STZ, resveratrol (10 mg/kg) was given for 15 days. Then the kidneys were evaluated histopathologically and the leptin and sirtuin 2 expressions were analyzed immunohistochemically. RESULTS: High glucose and fewer weight levels were seen in the STZ-induced diabetes mellitus group. The glucose levels in the RSV-administered diabetic group showed a tendency to decrease but not significantly. Decreased signs of histopathologic kidney damage was seen in the RSV-administered diabetic group, and an increased expression of leptin was seen in the diabetic kidney tissues. There were no significant differences of sirtuin 2 expression levels among the groups. CONCLUSION: It was observed that resveratrol caused changes in the diabetic kidney histology and leptin expression level. Resveratrol may be effective, with its antioxidant and antidiabetic effects, in the prevention of kidney damage caused by long-term hyperglycemia.

Protective effects of citicoline on TNBS-induced experimental colitis in rats.

The aim of this study was to investigate the effects of citicoline on the development of colitis and antioxidant parameters in rats subjected to tribenzene sulfonic acid (TNBS)-induced colitis. Twenty four Wistar Albino female rats were divided into four subgroups (n=6) (control, colitis control, colitis + 50 mg/kg citicoline, colitis + 250 mg/kg citicoline). Colitis was induced using an enema of TNBS and ethanol; following which citicoline was administrated for 3 days and effects of citicoline was subsequently evaluated. Based on microscopic damage scores, there was no difference between rats of the TNBS-colitis and 50 mg/kg citicoline treated groups, whereas treatment with 250 mg/kg citicoline, caused significant reduction in colon injury compared to that observed in rats of TNBS-colitis group. In terms of the biochemical analyses, myeloperoxidase (MPO), malondialdehyde (MDA), reduced glutathione (GSH), and IL-6 levels in rats from 250 mg/kg citicoline group were significantly different from that TNBS-colitis group. The levels of MPO, MDA, GSH and IL-6 in control rats were also significantly different those of rats in the TNBS-colitis group. Citicoline may have a positive protective effect on the inflammatory bowel disease treatment process and could, therefore, be used as an adjunct therapy in colitis. These effects of citicoline may exist through anti-inflammatory and antioxidant mechanism.

Protective effects of leflunomide on intestinal ischemia-reperfusion injury: leflunomide against intestinal ischemia-reperfusion.

AIM: The aim of this study was to investigate the possible protective effects of leflunomide, which has antioxidant and anti-inflammatory properties, against intestinal IR injury in rats. MATERIALS AND METHODS: Forty female Wistar albino rats were divided into six groups: control (n = 5), drug control (n = 7), sham operated (n = 7), IR alone (n = 7), IR plus vehicle (IR + vehicle, n = 7) and IR plus 20 mg/kg leflunomide (IR + Leflunomide, n = 7). While rats were pretreated intragastrically with leflunomide (20 mg/kg) and vehicle in three doses prior to the experiment, respectively, in the IR + Leflunomide and IR + vehicle groups, no additional application was done in the IR alone group. Intestines were exteriorized, and the superior mesenteric artery was occluded for 45 min ischemia, and then the clamp was removed for 120 min reperfusion. After the experiment, the intestines were removed for biochemical and histological examinations. Additionally, blood samples were taken for measurements of antioxidant parameters. RESULTS: The intestinal IR significantly increased the MDA level and MPO activity; however, treatment with leflunomide reversed those findings (P < 0.05). The CAT activity of the IR + Leflunomide group was significantly higher than in the IR groups (P < 0.05). The SOD activity was increased in the intestinal IR group, and leflunomide treatment reversed that, too (P <0.05). The light microscopic findings showed that IR caused mucosal necrosis and leflunomide treatment reduced the morphological alterations associated with IR (P < 0.05). CONCLUSION: Intestinal IR injury may be reversed by the anti-inflammatory and antioxidant actions of leflunomide.

Protective effects of caffeic acid phenethyl ester on intestinal ischemia-reperfusion injury.

AIM: Intestinal ischemia reperfusion (IR) causes tissue injury in two ways, starting a pro-inflammatory cascade and oxidative stress. The aim of this study was to investigate the possible protective effects of caffeic acid phenethyl ester (CAPE), which has antioxidant and anti-inflammatory properties, against intestinal IR injury in rats. MATERIALS AND METHODS: Forty male Wistar-Albino rats were divided into five groups: Sham, IR, IR plus ethanol (vehicle), IR plus 10 mg/kg (IR + 10CAPE), and 30 mg/kg CAPE (IR + 30CAPE) at the 30-min ischemic period. Intestines were exteriorized and the superior mesenteric artery was occluded for 45-min ischemia and then the clamp was removed for 120-min reperfusion. After the experiment, the intestines were removed for biochemical and light microscopic examinations. Additionally, blood samples were taken for plasma TNF-alpha measurement. RESULTS: The TBARS levels of the IR and IR + Ethanol groups were higher than the Sham group (P < 0.05). Both CAPE treatments decreased TBARS levels in comparison with the IR group (P < 0.05). In both CAPE-treated groups, while the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were increased compared to all other groups, which was similarly the case for the CAT activity compared to the Sham and IR + Ethanol groups (P < 0.05). There were no significant differences between GSH levels of all study groups. The TNF-alpha levels of the IR and IR + Ethanol groups were non-significantly increased compared to the Sham group (P > 0.05). The TNF-alpha levels of 10 and 30 mg/kg CAPE groups were non-significantly decreased compared to the IR group (P > 0.05). The tissue MPO activities of the IR and IR + Ethanol groups were higher than the Sham group (P < 0.05). The MPO activities of the IR + 10CAPE and IR + 30CAPE groups were not significantly different from the Sham group (P > 0.05). There was necrosis of mucosa in the IR and IR + Ethanol groups in light microscopic evaluations. Those changes were significantly reversed by 30 mg/kg CAPE treatment. CONCLUSION: The intestinal IR injury may be reversed by anti-inflammatory and antioxidant actions of the CAPE. However, 30 mg/kg CAPE treatment may be more efficient in preventing intestinal IR injury in rats.

The effects of caffeic acid phenethyl ester (CAPE) on TNBS-induced colitis in ovariectomized rats.

AIM: The aim of this investigation was to examine the effects of caffeic acid phenethyl ester (CAPE) on the development of colitis and antioxidant parameters in bilateral ovariectomized rats subjected to trinitrobenzene sulfonic acid (TNBS)-induced colitis. MATERIALS AND METHODS: Twenty-one Wistar Albino ovariectomized female rats were divided into four subgroups (n = 5 or 6) (colitis control, vehicle control, CAPE 10 and 30 mg/kg, respectively). Colitis was induced using an enema of TNBS and ethanol, following which CAPE was administrated for 3 days to induce colitis and effect of CAPE was subsequently evaluated. RESULTS: Based on microscopic damage scores, there was no difference between rats of the TNBS-colitis and the vehicle-treated groups, whereas treatment with CAPE 10 and 30 mg/kg, respectively, caused a significant reduction in colon injury compared to that observed in rats of the TNBS-colitis and vehicle-treated groups. The histologies of both treatment groups were not significantly different. In terms of the biochemical analyses, myeloperoxidase levels in rats from the CAPE 10 and 30 mg/kg groups were significantly different from that of the colitis control rats; however, the levels of malondialdehyde (MDA), catalase and reduced glutathione (GSH) were only significantly different from the levels found colitis control rats in rats administered 10 mg/kg. The levels of MDA, GSH and SOD in rats given CAPE were also significantly different from those of rats in the vehicle control group. These results were consistent with histological findings. CONCLUSION: CAPE may have a positive effect on the inflammatory bowel disease treatment process and could, therefore, be used as an adjunct therapy in colitis. These effects of CAPE may occur through antiinflammatory and antioxidant mechanisms.

The effect of leptin on adrenal glands in rats with streptozotocin-induced diabetes: an experimental study.

OBJECTIVE: To determine the cross-section area of adrenal medulla and the percentage of Ki-67 (a proliferation marker) of the adrenal gland in diabetic rats after leptin injection. STUDY DESIGN: Twenty-nine male Wistar rats were randomly divided into 3 groups: control (C) group (n = 9), diabetes mellitus (DM) group (n = 10) and leptin-injected diabetes mellitus (DM+L) group (n = 10). Experimental DM was induced by a single intraperitoneal dose of streptozotocin (40 mg/kg). After this, leptin (100 microg/kg) was injected subcutaneously for a period of 2 weeks in the diabetic group. RESULTS: An atrophy of adrenal medulla in the DM group was observed, and this atrophy returned to normal morphology after injection of leptin. In addition, an increase in the Ki-67 percentage was demonstrated in the zona reticularis layers in the DM+L group. CONCLUSION: Our study indicated that leptin stimulates the sympathoadrenal system and the androgen producing adrenal cortex in DM rats.

Melatonin ameliorates blood-brain barrier permeability, glutathione, and nitric oxide levels in the choroid plexus of the infantile rats with kaolin-induced hydrocephalus.

Hydrocephalus is a disabling disease for children, but current data concerning the effects of melatonin on ventricular enlargement are still limited. We have investigated the changes in the choroid plexuses (CPs) of ventricles and blood-brain barrier (BBB) of hydrocephalic rats. Forty-five Swiss Albino rats at age 2 weeks were divided into three equal groups: control, hydrocephalus, and melatonin-treated hydrocephalus groups. Hydrocephalus was induced by kaolin injection into the cisterna magna of all pups except control group and melatonin was given at a daily dose of 0.5 mg/100 g body weight for 4 weeks. At the end of the study, one animal from each group was examined using a gamma camera to study the disruption of BBB due to hydrocephalus. All animals were then killed for assay of glutathione (GSH) and nitric oxide (NO), as well as histological study of the CPs during the hydrocephalus. We observed an increased BBB activity was found in hydrocephalus group, while melatonin reversed these changes. It was found that NO concentration was elevated in hydrocephalus group and melatonin partly abolished the increased levels of NO. In contrast, GSH levels were significantly decreased in hydrocephalus group, while melatonin increased the tissue GSH level (p<0.01). Histologically, there was a significant alteration in the CPs of the ventricles of hydrocephalic animals, but it was regressed after melatonin treatment in consistent with the gross morphological changes related to hydrocephalus. In conclusion, our results clearly demonstrated for the first time the neuroprotective effects of melatonin upon hydrocephalus-induced CP changes in infantile rats, but further studies are needed to suggest melatonin as a candidate protective drug in children.