Evaluation of the Effects of STZ-Induced Diabetes on In Vitro Fertilization and Early Embryogenesis Processes

The aim of this study was to investigate the effects of experimentally induced diabetes on (a) germ cells, (b) in vitro fertilization (IVF) success rate, and (c) gap junction and cell adhesion molecule gene and protein expressions during the early blastocyst period. Germ cells were obtained from healthy and diabetic rats, analyzed for number, motility, and morphology, and used for IVF. After reaching the early blastocyst stage, the expressions of genes encoding gap junction proteins and cell adhesion molecules were analyzed by quantitative RT-PCR. Histomorphologically and immunohistochemically analyses were also performed. Diabetes significantly affected sperm number and motility and the development of oocytes. Gene expressions of β -catenin and connexin family members and protein expressions of E-cadherin and connexin-43 significantly decreased in groups including germ cells isolated from diabetic rats. Connective tissue growth factor expression increased in groups that included sperm cells isolated from diabetic male rats, whereas mucin-1 expression increased in the group that included oocytes isolated from diabetic female rats paired with sperm cells isolated from healthy male rats. In summary, experimentally induced diabetes was found to influence gap junctions, cell adhesion molecules, and associated proteins which all have important roles in germ cell maturation, fertilization, and development.

Evaluation of an elderly care training programme for women

BACKGROUND

Caregiving across different cultures has been perceived conventionally as a private or family responsibility, predominantly performed by women who accept their caregiving as part of their gender role.

AIM

This study aimed to design, deliver, and evaluate an elderly training programme for women by assessing their knowledge, attitudes and skills as a lay caregiver. Encouraging the women to find suitable positions for employment in private or governmental institutions was the further objective of the study.

DESIGN

The study was a quasi-experimental one-group pre-test post-test design.

METHODS

The study was conducted in a solidarity centre for women and in a nursing home for the elderly. The sample covered 120 women selected from the community by convenience sampling. Data were gathered through pre- and post-test evaluation and observation forms in 2 May-22 December 2005. The training programme consisted of 230 h of didactic sessions, demonstrations and clinical practices.

FINDINGS

The mean change in the participants' knowledge score (pre-test: 41.44 +/- 0.92; post-test: 71.16 +/- 1.34) demonstrated a statistically significant improvement in their knowledge. According to clinical observations, most of them displayed satisfactory caring and communication skills towards the elderly. Virtually all participants reported increased skill, knowledge and confidence.

CONCLUSION

The developed training programme was effective, resulting in an increased knowledge, the acquisition of good attitudes towards the elderly, and performing satisfactory caring and communication skills. Similar community-based programmes managed by nurses are recommended to support non-professional caregivers. The research is not only an innovative but also a revolutionary model to promote women.

Constructive effect of exogenous melatonin against osteoporosis after ovariectomy in rats

OBJECTIVE

To analyze histomorphometric, densitometric and biochemical effects of melatonin on osteoporosis in ovariectomized rats.

STUDY DESIGN

Wistar rats were divided into 6 groups. Group C: control; Group I: bilateral ovariectomy (OVX); Group II: OVX + vehicle; Group III: OVX + 10 mg/kg/day melatonin (MLT); Group IV: OVX + 30 mg/kg/day MLT; Group V: sham + 10 mg/kg/day MLT. Cortex, trabecula, osteoblast and osteoclast numbers were evaluated on vertebra and femur histomorphometrically. Hydroxyproline analysis was used to determine collagen content of femur and vertebrae. Bone mineral density and bone mineral content were measured.

RESULTS

Trabecular thickness and trabecular area of vertebra and femur and cortical thickness of femur showed remarkable decrease after OVX, but increased after MLT treatment in the OVX+MLT groups. Following OVX, no statistically significant difference was found in number of osteoblasts or osteoclasts, trabecular number or levels of hydroxyproline after treatment with MLT. OVX caused significant decrease in bone mineral density, but treatment with MLT was unable to reverse this effect.

CONCLUSION

MLT may trigger microscopic changes in bone, and time of application is critical for clinical recovery. It can be effective in helping treat postmenopausal osteoporosis. However, it is contraindicated in women who have normal-functioning ovaries.

Chemotherapy influences inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) activity on 3D breast cancer cell line

Multicellular tumor spheroids (MTS) are three-dimensional structural forms of tumors grown in vitro in the laboratory. In this study, the aim was to determine the regulation of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expressions on MTS in response to treatment with the commonly used anti-cancer drugs Doxorubicin and Docetaxel. The spheroids were generated using the "liquid overlay" technique. The distribution of both iNOS and eNOS was detected using indirect immunohistochemistry, while the expression of both iNOS and eNOS was measured using Western blots. Additionally, S-phase analysis using 5-bromo-2'-deoxyuridine (BrdU) was done on the MTS after treatment with doxorubicin, docetaxel, and a combination of the two. The Griess method was used to measure nitric oxide (NO) production in the cells. An increase in iNOS immunoreactivity and a decrease in eNOS immunoreactivity were observed after doxorubicin treatment, when compared with the other groups. Furthermore, upregulation of iNOS and downregulation of eNOS were detected in doxorubicin-treated cells using Western blotting. Insignificant iNOS expression was observed in all of the groups, and it was particularly low in the control and drug combination groups. NO production was also found to be significantly high after docetaxel treatment, and cell proliferation decreased after doxorubicin treatment. In conclusion, chemotherapy influences NOS activity differently with the presence of different drugs. The results with iNOS show that doxorubicin is a more effective drug than docetaxel, and a drug combination may play a helpful role in the suppression of tumorigenicity and cancer metastasis. Interestingly, eNOS expression increased after the addition of both docetaxel and the drug combination, and it was found to negatively correlate with the histological grade of the tumor. Therefore, analyzing the expression of both iNOS and eNOS might be very useful for targeting the treatment of breast carcinoma and obtaining better information on prognosis.

Role of Intercellular Communications in Breast Cancer Multicellular Tumor Spheroids After Chemotherapy

Tumor heterogeneity is an important feature that is especially involved in tumor aggressiveness. Multicellular tumor spheroids (MTS) may provide some benefits in different steps for investigation of the aggregation, organization, differentiation, and network formation of tumor cells in 3D space. This model offers a unique opportunity for improvements in the capability of a current strategy to detect the effect of an appropriate anticancer agent. The aim of this study was to investigate the cellular interactions and morphological changes following chemotherapy in a 3D breast cancer spheroid model. Distribution of the gap junction protein "connexin-43" and the tight junction protein "occludin" was investigated by immunohistochemistry. Cellular interactions were examined by using transmission and scanning electron microscopies as well as light microscopy with Giemsa staining after treating cells with doxorubicin, docetaxel, and doxorubicin/docetaxel combination. Statistical analyses showed significant changes and various alterations that were observed in all groups; however, the most prominent effect was detected in the doxorubicin/docetaxel combination group. Distinct composition as a vessel-like structure and a pseudoglandular pattern of control spheroids were detected in drug-administered groups. Immunohistochemical results were consistent with the ultrastructural changes. In conclusion, doxorubicin/docetaxel combination may be more effective than the single drug usage as shown in a 3D model. The MTS model has been found to be an appropriate and reliable method for the detection of the changes in the expression of cellular junction proteins as well as other cellular proteins occurring after chemotherapy. The MTS model can be used to validate the effects of various combinations or new chemotherapeutic agents as well as documentation of possible mechanisms of new drugs.

The effect of exogenous melatonin administration on trabecular width, ligament thickness and TGF-β1 expression in degenerated intervertebral disk tissue in the rat

Intervertebral disk (IVD) degeneration, a complex pathological condition of varying origins, causes low back pain. Degenerative changes in IVD tissue affect the adjacent vertebral structure, resulting in a decreased vertebral trabecular width. It has been suggested that transforming growth factor-beta 1 (TGF-beta(1)) may have a role in the repair of connective tissue, as it occurs in the IVD degeneration process. In this study, we investigated the effects of exogenous melatonin (MEL) administration on vertebral trabecular width, ligament thickness and TGF-beta(1) expression in degenerated IVD tissue. Fifteen adult male Swiss Albino rats were divided randomly into three groups; nonoperated control, operated degeneration, and MEL treatment groups. In the operated degeneration and MEL treatment groups, cuts were made parallel to the end plates in the posterior annulus fibrosus at the fifth and tenth vertebral segments of the tail to induce IVD degeneration. In each group, TGF-beta(1) immunoreactivity and morphometry of vertebral trabecular width and anterior and posterior ligament thickness were evaluated. Histologically, disorganisation and irregularity of collagen fibres was seen in the degenerated (operated) IVD. Increased TGF-beta(1) expression in multinuclear chondrocytes was also observed as was decreased vertebral trabecular width. Importantly, the reduction of trabecular width observed in the operated degenerated group was reversed after MEL administration (p<0.0001). Similarly, TGF-beta(1) expression in multinuclear chondrocytes was dramatically increased after exogenous MEL application. Thus, there was a regression in histopathological changes after MEL treatment, with disk appearances similar to those of the control group. Based on our findings, we suggest that MEL activates the recovery process in the degenerated IVD tissue, possibly by stimulating TGF-beta(1) activity. This is the first report investigating the involvement of the pineal hormone MEL in the repair of rat IVD.

Effect of apoptosis and response of extracellular matrix proteins after chemotherapy application on human breast cancer cell spheroids

Multicellular tumor spheroid (MTS) represents a three-dimensional structural form of tumors in laboratory conditions, and it has the characteristics of avascular micrometastases or intervascular spaces of big tumors. Recent studies indicate that extracellular matrix (ECM) proteins play a critical role in tumor metastasis, therefore normal and cancer cells require an ECM for survival, proliferation and differentiation. Doxorubicin and Docetaxel are widely used in the therapy of breast cancer, as well as in in vivo and in vitro studies. In this study, we examined the effect of apoptosis and proliferation of cells on the human breast cancer cell line, MCF-7, by using p53, bcl-2 and Ki67 gene expression, and the tendency to metastasis with extracellular matrix proteins, laminin and type IV collagen after chemotherapy in the spheroid model. The apoptotic cell death in situ was detected by TUNEL method. TUNEL-positive cells and positive immunoreactivities of laminin, type IV collagen, p53 and, bcl-2 were detected in the control group. There was no laminin and type IV collagen immunoreactivities in spheroids of drug groups. While TUNEL-positive cells and p53 immunoreactivity were detected in Docetaxel, Doxorubicin and Docetaxel/Doxorubicin groups, p53 immunoreactivity was not observed in the Docetaxel group. There was no bcl-2 immunoreactivity in either drug group. In addition, we did not detect Ki67 immunoreactivity in both control and drug treatment groups. However, the absence of Ki67 protein in MCF-7 breast multicellular tumor spheroids is possibly related to the cells in G0 or S phase. These chemotherapeutic agents may affect the presence of ECM proteins in this in vitro model of micrometastasis of spheroids. These findings suggest that the possible mechanism of cell death in Doxorubicin and Docetaxel/Doxorubicin treatment groups is related to apoptosis through the p53 pathway. However, we considered the possibility that there is another control mechanism for the Docetaxel group.

Evaluation of the relationship between inducible nitric oxide synthase (iNOS) activity and effects of melatonin in experimental osteoporosis in the rat

Inducible nitric oxide synthase (iNOS) plays a critical role in the pathogenesis of osteoporosis. iNOS generates nitric oxide (NO), a free radical contributing to the imbalance between bone formation and resorption caused by estrogen depletion. Melatonin is the major product of the pineal gland which is known to diminish iNOS expression and NO production significantly. The aim of this study was to determine the distribution of iNOS and the amount of apoptotic cells after melatonin treatment in ovariectomized rats. Since previous studies have shown that constitution of bone formation is primarily sustained in nucleus pulposus and epiphyseal cartilage, experiments were carried out on nucleus pulposus and epiphyseal cartilage; additional quantitation of osteoblasts and osteoclasts were evaluated on vertebral area as well. Vertebral sections of ovariectomized rats were obtained from formalin-fixed and parafin-embedded blocks. iNOS expression and quantitation of apoptotic cells in nucleus pulposus and epiphyseal cartilage were evaluated using indirect immunoperoxidase and TUNEL techniques, respectively. The number of osteoclasts and osteoblasts in trabecular bone was determined using histomorphometry. Ovariectomy increased iNOS expression and the number of apoptotic cells in nucleus pulposus and epiphyseal cartilage, whereas a 4-week treatment with melatonin (10 mg/kg/day) resulted in the reduction of both effects. These data indicate that there is strong influence of melatonin application on expression of iNOS, apoptosis, osteoclast and osteoblast numbers after ovariectomy. In conclusion, melatonin besides its usual use as an antiaging hormone, may also be an effective hormone in treatment of bone changes in estrogen deficiency states.

Chronic changes in cerebrospinal fluid pathways produced by subarachnoid kaolin injection and experimental spinal cord trauma in the rabbit: their relationship with the development of spinal deformity. An electron microscopic study and magnetic resonance imaging evaluation

Post-traumatic cystic changes in cerebrospinal fluid (CSF) pathways such as ventriculomegaly and/or hydrosyringomyelia are not uncommon, but their characteristics have not yet been fully clarified. This study was designed to investigate the alterations affecting the CSF pathways in rabbits at a late stage, and to clarify the relationship between these changes and the development of spinal deformity. In this study, a total of 60 New Zealand white rabbits were used and they were segregated into four different groups of 15 animals each: sham-operation group, kaolin group, and kaolin plus mild trauma group and kaolin plus severe trauma group. The animals were subjected to radiological investigation using direct X-ray study and magnetic resonance imaging (MRI) after 4 months. The thoracic spinal cords of the animals were dissected after intracardiac perfusion-fixation with 10% formalin for light microscopy and 2.5% glutaraldehyde for transmission electron microscopic study. Following the sectioning and staining procedures, the histological characteristics of the spinal cords were evaluated with light microscopy and transmission electron microscopy. A spinal deformity developed in 90% in rabbits in both kaolin injection group and spinal trauma groups. MRI revealed generalized dilatation of the ventricular system and the central canal of the spinal cord after the kaolin injection with/without trauma in this study. Gross morphologic examination showed some enlargement of entire CSF pathways in these groups. All animals with central canal dilatation had mild or severe scoliotic and kyphotic deformities. In a light microscopic study, a denuded ependymal line and multicyst formations in periependymal areas were found in both kaolin injection and spinal trauma groups. Ultrastructurally, an apical flattening of the ependyma, microcysts in the ependymal cells, axonal degeneration, demyelination, and loss of ependymal cells adjacent mild spongy were found in the spinal cords of animals in these groups. To the best of our knowledge, this is the first study to investigate the chronic effects of spinal cord injury (SCI) on the CSF pathways and their relationship with the development of spinal deformity in an experimental model of kaolin injection and trauma, using MRI as well as light and transmission electron microscopy. In the light of this study, the severity of spinal cord injury on the development of some degenerative findings in the spinal cord was clear, but further clinical and experimental studies using dynamic imaging techniques will be valuable.

Assessment of effects of pinealectomy and exogenous melatonin administration on rat sciatic nerve suture repair: an electrophysiological, electron microscopic, and immunohistochemical study

BACKGROUND

Collagen scar formation at the cut end of a nerve, an important problem in clinical practice for neurosurgeons in peripheral nerve surgery, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits nerve regeneration. Researchers attempt to control collagen accumulation in the formation of neuroma by various physical and chemical methods, but these have yielded only limited functional success. This is the first experimental study investigating the effects of melatonin (MLT) on nerve repair and neuronal regeneration in rat sciatic nerve suture repair.

METHODS

The hypothesis that exogenous MLT administration may inhibit the formation of neuroma in peripheral nerve surgery was investigated in rat sciatic nerve model. In this study, a total of 80 rats were used for control groups (Groups Ia, Ib, IIa, and IId), MLT group (Group Ic), surgical pinealectomy (Px) groups (Groups IIb and IIc), and group of MLT treatment following Px procedure (Group IIe). All animals underwent a surgical intervention consisting of bilateral sciatic nerve section and primary suture repair. At 8 weeks after repair, the animals were killed following completion of recording of nerve action potentials (NAPs). Then, unilateral sciatic nerve specimens including the suture repair region were carefully removed and the excised segments were processed for electron microscopy examination. Afterwards, contralateral sciatic nerve specimens from two animals from each group were removed and stained for immunohistochemical analysis.

RESULTS

Results of morphometric analysis revealed that Px procedure caused an elevation of collagen content of the sciatic nerve and macroscopic neuroma formation, and that there was a statistically significant reduction in collagen content of the same region in pinealectomized animals treated with MLT (p<0.001). Accordingly, electrophysiological findings demonstrated that the stimulus intensities required to excite a NAP response were increased in surgical Px group, but the presence of a reduced threshold response was found in the group treated with MLT following Px procedure (p<0.01). Immunohistochemical staining for Type I collagen and Type III collagen was markedly more intense in the epineurium of animals after Px. Virtually no or only weak staining was observed in animals in control groups and the MLT treatment group. Results of immunohistochemical analysis revealed that surgical Px procedure caused a strong immunoreactivity for Type I collagen and Type III collagen in all connective tissue planes of the nerve, especially in the epineurium, and there was a statistically significant reduction in immunoreactivity of the repair region in animals receiving MLT treatment after Px procedure (p<0.001).

CONCLUSION

This study demonstrates that exogenous MLT administration significantly inhibits collagen accumulation in the formation of neuroma in the suture repair site and thereby improves nerve regeneration. From a clinical standpoint, the positive effect of MLT administration on neuroma formation and nerve regeneration seems a particularly attractive treatment option. Therefore, we believe that nerve repair with addition of MLT may be a worthwhile option in addition to other treatment modalities in case of MLT deficiency, such as aging. However, further experimental and clinical studies using functional analysis warranted to confirm this result in future.

Amlodipine and glutathione cycle in hypercholesterolaemia

OBJECTIVE

Effects of amlodipine on lipid peroxidation and alterations in glutathione and related enzymes in blood and aortic tissue were investigated in a cholesterol-induced atherosclerotic rabbit model.

METHODS AND RESULTS

New Zealand white male rabbits were fed with regular chow (group I), chow supplemented with I% cholesterol (group II), regular chow plus amlodipine 5 mg/kg/day p.o. (group III) and I% cholesterol diet supplemented with amlodipine (group IV) for 8 weeks. Cholesterol, malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GSH-PX) and glutathione reductase (GSH-Rd) were determined in blood samples drawn before and after the experimental period. Aortic tissue was examined morphologically for atherosclerotic changes and tissue cholesterol, MDA, GSSG, GSH-PX, GSH-Rd and glutathione-S-transferase (GST) were measured. After 8 weeks, blood cholesterol, MDA, GSSG and GSH-PX were elevated in groups II and IV; GSH was reduced in group IV; MDA levels were higher in group II than in group IV. Aortic tissue investigations revealed higher cholesterol and MDA concentrations in group II than in group IV. Morphological examination of aortic tissues exhibited endothelial disarrangement and lipid deposition in group II. Histopathological alterations related to atherogenesis were less in group IV than in group II.

CONCLUSIONS

Amlodipine reduced the increase in oxidative stress by inhibiting excessive MDA production. Accelerated glutathione redox cycle activity of erythrocytes from animals supplemented with amlodipine suggests that this drug may reduce oxidative stress by enhancing the glutathione system. However, this drug does not seem to affect the glutathione redox cycle in the aortic tissue.

Alterations of brain tissue in fetal rats exposed to nicotine in utero: possible involvement of nitric oxide and catecholamines

Histopathological changes in the brains of embryos from female rats treated with nicotine during pregnancy and possible involvement of nitric oxide (NO) and catecholamines in the nicotine-induced abnormalities of developing brain were investigated. Sexually mature female Wistar rats were given 1, 2, and 3 mg/kg nicotine hydrogen tartrate (NHT) subcutaneously for 20 days after mating. Levels of cotinine, a nicotine metabolite, in the maternal plasma increased dose-dependently. Fetus and fetal brain weights were significantly lower in all nicotine-treated groups. Light microscopy of hippocampal CA1 area showed a decrease in the number of cells per unit area. Electron microscopy of the same region revealed a dose-dependent increase in intracytoplasmic edema, mitochondrial swelling, dilation of rough endoplasmic reticulum, nuclear configurative abnormalities, and condensation of the nuclear chromatin. Nitrate + nitrite levels in fetal brain homogenates were significantly lower in the groups treated with 2 and 3 mg/kg NHT. Norepinephrine and normetanephrine (NMN) levels were significantly higher in 2 and 3 mg/kg NHT groups, as well as dopamine, 3-methoxy-4-hydroxyphenylethyleneglycole (MHPG), and dihydroxyphenylacetic acid levels in the 3-mg/kg NHT group. In conclusion, maternal nicotine exposure may lead to structural abnormalities of the fetal brain tissue and may result in decreased levels of NO and increased levels of catecholamines and their metabolites.

The effects of pineal gland transplantation on the production of spinal deformity and serum melatonin level following pinealectomy in the chicken

Pinealectomy frequently produces spinal deformity in some animal models, but the precise biological mechanism of this phenomenon remains obscure. The current study investigated the effects of an autograft pineal body on the development of spinal deformity and serum melatonin (MLT) concentration after pinealectomy in the chicken. Thirty-six chickens (2 days of age) were divided into three equal groups. While the removal of the pineal gland was performed in groups B and C, a pineal body autograft was surgically implanted into the body wall musculature only in the pineal transplantation group (group C). Chickens in which no surgical intervention was performed served as intact controls (group A). Posteroanterior radiographs of the spines of the chickens were taken at the age of 8 weeks. These were used to determine Cobb angles and to measure the rib-vertebra angles (RVA) on the concave and convex sides of the curves, from which data the difference between the convex and concave RVA (the RVAD) was calculated. At the end of the study, serum MLT levels were determined using the enzyme-linked immunosorbent assay method, and histopathological examination of specimens from all the groups was performed. The results were compared using one-way analysis of variance followed by Duncan's test for pairwise comparisons or by the Kruskal-Wallis test followed by the Mann-Whitney U tests for comparisons between two groups. In this study, the serum MLT levels in groups B and C were significantly lower than those in group A ( P<0.05). However, scoliosis developed in only 7 of 12 (58%) in group B and 6 of 12 (50%) in group C. The average Cobb angle and RVAD in groups B and C were significantly larger than those found in group A ( P=0.000 and P=0.001, respectively). Interestingly, there were no significant differences in either serum MLT levels or development of scoliosis between groups B and C. From the results of the current study, it is evident that the intramuscular pineal gland transplantation following pinealectomy in young Hybro Broiler chickens has no significant effect on the development of spinal deformity and serum MLT level. In the light of this result, the role of MLT in the development of spinal deformity in chickens after pinealectomy remains controversial, and further investigations are warranted.

Contradictory effects of chlorpromazine on endothelial cells in a rat model of endotoxic shock in association with its actions on serum TNF-alpha levels and antioxidant enzyme activities

We examined the effects of the phenothiazine derivative, chlorpromazine on thoracic aortic endothelial cell histology (14 h after LPS challenge) in a model of endotoxic shock in rats. Since excessive formation of tumor necrosis factor-alpha (TNF-alpha) and oxygen-derived free radicals contribute to endothelial injury in endotoxemia, we also evaluated the effect of the drug on the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase in liver tissue in this model and tried to find out whether this possible effect was associated with a change in serum TNF-alpha levels (measured 90 min after chlorpromazine administration). Endotoxemia was induced by a single i.p. injection of lipopolysaccharide (LPS) (5 mg kg(-1) in 1.5 ml of saline; LPS from Escherichia coli serotype 055:B5, L-2880, Sigma Chemical Company). Electron microscopic evaluation of the aortas revealed that chlorpromazine (administered 30 min prior to LPS challenge), in smaller doses (3 mg kg(-1)) ameliorated the endothelial cell injury caused by LPS, whereas it caused deterioration of endothelial cell morphology in higher doses (10 and 25 mg kg(-1)). Chlorpromazine administration caused a significant reduction in serum TNF-alpha levels, which was correlated well with an increase in SOD activity in all drug doses (3, 10 and 25 mg kg(-1)). Catalase activity was increased only in the 25 mg kg(-1) chlorpromazine group.

Comparison of the effects of dietary saturated, mono-, and n-6 polyunsaturated fatty acids on blood lipid profile, oxidant stress, prostanoid synthesis and aortic histology in rabbits

BACKGROUND/AIMS

To compare the effects of saturated, monounsaturated and polyunsaturated n-6 fatty acid-enriched diets on the development of atherosclerosis and thrombosis in New Zealand white male rabbits, 3- to 6-month-old animals were supplemented daily (10 g/100 g diet) with butter (n = 8), olive oil (n = 8) or corn oil (n = 8) by oral administration for 7 weeks.

METHODS

Total cholesterol (TC), HDL- (HDL-C) and LDL-cholesterol (LDL-C), triglycerides (TG), apolipoprotein A-1 (ApoA-1), apolipoprotein B (ApoB), lipid peroxides as thiobarbituric acid-reactive substances (TBARS), thromboxane B2 (TXB2) and 6-ketoprostaglandin F(1alpha) (6-ketoPGF(1alpha)) concentrations were determined in blood samples drawn before and after each group was fed the different dietary regimens. Histological examination was performed on the aortic tissues.

RESULTS

After 7 weeks, TC, ApoB and TXB2 increased significantly (p < 0.05) in the butter-fed animals compared to pre-experimental concentrations. Olive oil administration lead to a significant (p < 0.05) decrease in TC and ApoB levels. The corn oil-enriched diet decreased TC, LDL-C concentrations, TC/HDL-C ratios and 6-ketoPGF(1alpha) (stable metabolite of prostacyclin-PGI2; p < 0.05 for all) but increased TBARS levels and TXB2/6-ketoPGF(1alpha) ratios. Light microscopic findings were in accordance with these biochemical alterations.

CONCLUSION

Although effective in lipid lowering, corn oil increased oxidant stress as evidenced by increased TBARS and induced endothelial damage which lead to a reduction in PGI2 synthesis and consequently to an increase in the TXB2/6-ketoPGF(1alpha) ratio. Olive oil administration did not induce oxidant stress and it had no affect on PGI2 and TXB2 levels which are implicated in platelet aggregation. These findings suggest that oleic acid is more effective than linoleic acid in the protection of endothelial integrity.

Changes in vascularity of cartilage endplate of degenerated intervertebral discs in response to melatonin administration in rats

We carried out an experimental investigation of cartilage endplate vascularity of degenerated intervertebral discs produced by exogenous melatonin (MEL) treatment. Adult Swiss albino rats were divided into three groups: control, operated degeneration, and MEL treatment. There were five rats in each group and, using a posterior approach, cuts were made parallel to the endplates in the posterior annulus fibrosus in five consecutive intervertebral discs between the 5th and 10th vertebral segments of the rats' tails. At 8 weeks, five of these animals were treated with exogenous MEL (s.c. injection of 30 microg/100 g body weight daily for 4 weeks). In each experimental group, one animal was examined using CT scanner to study the density of the cartilage endplate of the disc. To evaluate the bone growth and vascularity of the cartilage endplate region, the animals were killed for subsequent histopathological evaluation. We found that the vascular channel counts and percentage areas from animals treated with MEL were significantly lower than from the operated degeneration animals. Accordingly, the density histogram in the MEL group showed a spike profile for both the vertebral body and the cartilage endplate, indicating an increase in the amount of higher density tissues in these regions. Our results demonstrate that the use of MEL reduces the cartilage endplate vascularity of degenerated intervertebral discs, suggesting that it may have an osteoinductive effect on bone formation. Further studies are needed to characterize fully the relevance of our findings for the treatment of disorders such as postmenopausal osteoporosis.

The effects of calcium channel antagonist nimodipine on end-plate vascularity of the degenerated intervertebral disc in rats

The vascular channels at the end-plate of the intervertebral disc are very important in maintaining a healthy disc. With age, a reduction of the nutrition of the avascular nucleus pulposus is inevitable. On the other hand the calcium channel antagonist nimodipine has been shown to have a positive effect on blood flow in the region of the vertebral end-plate. To evaluate the effects of nimodipine on the end-plate vascularity in the degenerative discs, we have produced an experimental disc degeneration and evaluated the radiological and histopathological features of the end-plate of the degenerated discs. Adult rats were divided into 3 groups: control (n=5), operated degeneration (n=5), and nimodipine treatment (n=5). Using a posterior approach, a cut was made parallel to the end-plates in the posterior annulus fibrosus in 5 consecutive intervertebral discs between the 5th and 10th vertebral segments of the tails of adult Swiss Albino rats. At 8 weeks, 5 of these animals were treated with nimodipine. In each experimental group, 1 animal was examined using computed tomography (CT) to study the density of the cartilage end-plate of the disc. Then, the animals were sacrificed for subsequent histopathological evaluation. We found that the vascular channel counts and percentage areas from animals treated with nimodipine were higher than from both the non-operative control and operated degeneration groups, although these were not statistically different. Accordingly, the profile of the density histogram in the nimodipine-treated group showed a wide plateau, indicating an increase in the vascularity in this region. From our results, we suggest that nimodipine enhances vascularisation of the cartilage end-plate in the disc. It is possible that the increased proportion of vascular contacts at the end-plate has a beneficial effect in the nutrition of the disc. However, further experimental studies will be needed to determine the validity of this statement in animals or human beings.