Influence of hormonal imbalance on the integrity of seminiferous epithelium in the testes of adult rats chronically exposed to letrozole and rats exposed to soya isoflavones during the prenatal period, lactation, and up to sexual maturity.

The structural integrity of the germ cells in the seminiferous epithelium and the correct process of spermatogenesis are made possible by proteins that participate in the formation of different types of junctions. This study was performed on samples of the testes of 4 groups (2 experimental and 2 corresponding control) of male Wistar rats. In the first experimental group, the adult rats received letrozole - a nonsteroidal inhibitor of cytochrome P450 aromatase (P450arom). The second experimental group was exposed to soya isoflavones during the prenatal period, lactation, and up to sexual maturity. The aim of this study was to examine the immunoexpression of ß-catenin, N-cadherin, occludin, connexin43, annexin V, and advanced glycation end products (AGE) in the seminiferous epithelium of rat testes with chronic estrogen deficiency and of rats exposed to soya isoflavones. Series of sections of the testes were stained using PAS and silver impregnation. Moreover, immunohistochemistry tests were performed. A semi-quantitative determination of protein immunoexpression was performed using Image J. The number of annexin V positive Sertoli cells per tubule were counted manually. Comparisons between the experimental and corresponding control groups were performed using a non-parametric Mann-Whitney U test. The most common alterations were prematurely sloughed germ cells in the lumen of the seminiferous tubules and invaginations of the seminiferous tubules. We observed a lower number of annexin V positive Sertoli cells and a lower expression of N-cadherin and occludin in the seminiferous epithelium of both groups of rats with hormonal imbalances. Moreover, a higher expression of AGE, a lower expression of connexin 43 and a lower amount of reticular fibers in the basal lamina of seminiferous tubules was present in rats treated with letrozole and a higher expression of ß-catenin was found in rats exposed to soya isoflavones. The hormonal imbalance between androgens and estrogens resulted in a decreased number of annexin V positive Sertoli cells. This may be associated with a failed clearance of apoptotic germ cells that leads to disturbances in the blood-testis-barrier (BTB) by affecting the expression of junctional proteins in the seminiferous epithelium. Moreover, a decreased level of estrogens was also associated with an increased expression of AGEs and with a changed composition of basal lamina in the seminiferous tubules of rats. These changes could lead to germ cell sloughing and invaginations of the seminiferous tubules.

Inhibition of erythrocyte phosphoribosyltransferases (APRT and HPRT) by Pb2+: a potential mechanism of lead toxicity.

Many reports show that red blood cells of people exposed to lead have a decreased ATP concentration, decreased adenylate energy charge value and many metabolic and morphological abnormalities. Since the synthesis of nucleotides in erythrocytes occurs only through salvage pathways, we hypothesized that a decrease in nucleotide concentrations may be caused by lead-induced inhibition of erythrocyte phosphoribosyltransferases: adenine APRT (EC 2.4.2.7) and hypoxanthine-guanine HPRT (EC 2.4.2.8). These enzymes enable the reutilization of purine bases (adenine, guanine, hypoxanthine) converting them to mononucleotides (AMP, GMP, IMP), substrates for the synthesis of high-energy nucleotides. To confirm the hypothesis two experiments were performed: (i) in vitro, using a lysate of human erythrocytes incubated (5, 10, 30min) with lead ions (100microM, 10microM, 1microM, 500nM, 100nM lead acetate) and 100microM sodium acetate for the control, (ii) in vivo, using a lysate of rat erythrocytes taken from rats chronically exposed to lead (0.1% lead acetate in drinking water for 9 months, resulting in whole blood lead concentration 7microg/dL). The activities of APRT and HPRT were determined using HPLC method, which allowed concurrent determination of the activity of both enzymes in erythrocyte lysates. We have shown that, lead ions: (i) moderately inhibit both phosphoribosyltransferases in erythrocytes, this influence being detectable even at very low concentrations (ii) participate in hemolysis, the intensity of which negatively correlates with the activity of phosphoribosyltransferases. Our results indicate the necessity of further research on the role of lead-induced APRT and HPRT inhibition as one of the mechanisms of lead toxicity.

Disturbances of energetic metabolism in rat epididymal epithelial cells as a consequence of chronic lead intoxication.

Adult male Wistar rats were intoxicated with 1% lead acetate (PbAc) administered in drinking water for nine months, which amounts to a period five times longer than the duration of one spermatogenesis. There were mitochondrial ultrastructure disorders of epididymal epithelial cells observed in PbAc-treated rats; also a significant lead-induced decrease in ATP concentration in epididymal epithelial cells (by 32%, P < 0.05), Adenylate Energy Charge value (AEC) (by 8%, P < 0.05) and an increase in ADP (28.5%, P < 0.05), AMP (27%, P < 0.05) and adenosine (by 56%, P < 0.05). The results were measured using high performance liquid chromatography (HPLC) and detected even at low lead concentrations in whole blood (M:7.03 µg/dL; Q1-Q3: 2.99-7.65). The function of mitochondria in cultured epididymal epithelial cells of control and PbAc-treated animals were evaluated using fluorophores: Mitotracker Green FM and JC-1. After incubation with Mitotracker Green FM, we observed active mitochondria producing bright green fluorescence in the cytoplasm of cultured epididymal epithelial cells, both in the control group and the Pb-treated animals. Incubation of cultured epididymal epithelial cells of animals from both groups produced red-orange fluorescence with the mitochondrial JC-1 probe indicating mitochondria with high membrane potential (ΔΨm > 80-100 mV) and green fluorescence in the mitochondria with low membrane potential (ΔΨm < 80 mV). The results showed that a chronic low-level exposure to lead, even without severe clinical symptoms of contamination, disrupted the ultrastructure and energy metabolism of mitochondria in epididymal epithelial cells.

Modulatory effect of inulin with soya isoflavones on plasma lipid profile and liver SCD-18 index in rats with induced type-2 diabetes mellitus.

Obesity and type-2 diabetes are often associated with nonalcoholic fatty liver disease (NAFLD). Soya isoflavones act as antidiabetic agents and protect against NAFLD. There are data suggesting that inulin may increase the plasma concentration and effect of soya isoflavones. The aim of the present study was to compare the effect of soya isoflavones, as opposed to the effect of soya isoflavones with inulin, on plasma lipid profile, liver morphology, and liver fatty acids in rats with induced type-2 diabetes mellitus. Data were collected on thirty-six male Sprague-Dawley rats divided into control and diabetic groups. Animals in the diabetic (DM) group were on a high-fat diet and were injected with low doses of streptozotocin. Animals in the control groups were fed a regular diet and were injected with a buffer. After the injections, the animals were divided into three groups of nondiabetic rats (nDM)-controls (c-nDM), rats treated with isoflavones (IS-nDM), and rats treated with isoflavones plus inulin (IS+IN-nDM)-and three parallel diabetic (DM) subgroups: controls (c-DM), rats treated with isoflavone (IS-DM), and rats treated with isoflavones plus inulin (IS+IN-DM). Hepatic steatosis and fibrosis were examined using hematoxylin-eosin staining and Mallory's trichrome methods respectively. Liver fatty acids were extracted and analyzed by gas chromatography. A lipid blood test was performed. The study showed significant changes in liver fatty acids, liver morphology, and plasma lipid profile. The estimated SCD-18 index significantly decreased in both the control and DM groups after isoflavone supplementation. The level of liver steatosis and fibrosis also decreased after isoflavone supplementation in the DM groups. The plasma lipid profile showed increased levels of HDL-C after isoflavone supplementation in the DM groups. These results support the protective use of isoflavones in liver steatosis and as beneficial to plasma lipid profile in individuals with diabetes. A novelty of this work is its comparison of supplementation using soya isoflavones with supplementation using both soya isoflavones and inulin. Surprisingly, additional supplementation with inulin modulates the positive effect of isoflavones.

Expression of E-SOD, GPX5 mRNAs and immunoexpression of Cu/ZnSOD in epididymal epithelial cells of finasteride-treated rats.

We studied the immunoexpression of Cu/Zn superoxide dismutase (Cu/ZnSOD) and mRNAs expression of extracellular superoxide dismutase (E-SOD), and epididymal specific glutathione peroxidase 5 (GPX5), in epithelial cells of caput and cauda epididymis of rats treated with finasteride, a steroid-based inhibitor of 5alpha-reductase. The 5alpha-reductase is known to exist in two isoforms. Both 5alpha-red1 and 5alpha-red2 catalyse the irreversible conversion of T into DHT. Formation of DHT in the epididymis is mostly due to the action of 5alpha-red2 and finasteride is more potent inhibitor of this isoform. Rats were treated with finasteride for 56 days covering the duration of one spermatogenesis (four cycles of the seminiferous epithelium). Although E-SOD mRNA is normally expressed in cells of cauda but not of caput epididymis, treatment with finasteride produced the E-SOD transcript in cells of caput epididymis too. The GPX5 transcript was detected in cells of caput epididymis of control and experimental rats, but the level of expression measured densitometrically was significantly lower in finasteride-treated rats. The immunoexpression of Cu/ZnSOD was also changed in epididymis of finasteride-treated rats. Finasteride appears to change the pattern of expression of antioxidant enzymes and may alter the protective function of the epididymis in relation to spermatozoa.

The effect of stem cell mobilisation with granulocyte colony-stimulating factor on the morphology of the haematopoietic organs in mice.

The cellular mobilisation of mice with granulocyte colony-stimulating factor (G-CSF) results in an egress of haematopoietic stem/progenitor cells from the bone marrow and an increase in their level in the peripheral blood. While the mobilisation process with different agents is widely studied, little is known about the morphology of the murine haematopoietic organs during the mobilisation. The purpose of this study was to examine the morphology of the bone marrow, spleen and liver in mice mobilised with G-CSF. To address this issue mice were injected subcutaneously with G-CSF for 6 consecutive days. Morphological analysis revealed an increase in the number of mature neutrophils close to the wall of sinusoids in the bone marrow as well as hypertrophy of the red pulp in the spleen. At the same time no morphological changes were noticed in the livers of G-CSF-mobilised mice. In conclusion, G-CSF induces discrete ultrastructural changes in the bone marrow, which intensify the transendothelial traverse of haematopoietic stem and progenitor cells from it. The changes in the spleen are related to repopulation of this organ by mobilised early haematopoietic cells circulating in the peripheral blood. We also noticed that the process of migration of haematopoietic cells from the bone marrow into the peripheral blood began on day 2 and was most pronounced on day 4 after stimulation with G-CSF.

Morphologic Changes in the Dermis After the Single Administration of Autologous Fibroblastic Cells: A Preliminary Study.

BACKGROUND: Aging is a multifactorial process defined by an accumulation of damage in all tissues and organs, including the skin, throughout the lifespan of an individual. The reduction of both cellular and extracellular matrix components of the dermis during the aging process is followed by the alteration of the morphology of the skin tissue. This study was conducted to assess skin morphology in men before and 3 months after the intradermal injection of autologous fibroblastic cells. METHODS: Tissue biopsies were surgically obtained before and 3 months after the treatment with autogenously harvested fibroblasts expanded in vitro, as well as after injection of phosphate-buffered saline. The thickness of collagen fiber bundles and number of fibroblasts in the dermis were analyzed in morphometric studies. The morphologic evaluation, using different methods of staining has been performed to analyze of extracellular matrix proteins, including collagen and reticular fibers, fibrillin-1-rich microfibrils, elastic fibers, and hyaluronic acid. RESULTS: After administration of the cells, we found a noticeable increase in the number of fibroblasts within the dermis, a significant enlargement in diameter of the collagen fiber bundles, and an improvement in the density of reticular fibers, fibrillin-1-rich microfibrils, and elastic fibers compared with the initial, steady-state condition. CONCLUSIONS: The administration of autogenous fibroblasts could be an effective and safe adjunctive therapy to conventional health care treatment to prevent and reduce the age-related accumulation of dermal tissue damage.

Effect of stem cell mobilization with cyclophosphamide plus granulocyte colony-stimulating factor on morphology of haematopoietic organs in mice.

Both granulocyte colony-stimulating factor (G-CSF) and cyclophosphamide (CY) are employed in the clinic as mobilizing agents to stimulate the egress of haematopoietic stem/progenitor cells (HSPC) from bone marrow (BM) into peripheral blood (PB). However, although both compounds are effective, the simultaneous administration of G-CSF + CY allows for optimal mobilization. The aim of this study was to compare morphological changes in major haematopoietic organs in mice mobilized by G-CSF + CY. We employed the standard G-CSF + CY mobilization protocol, in which mice were injected at day 0 with a single dose of CY followed by daily injection of G-CSF for 6 consecutive days. We noticed that the cytoreductive effect of CY on BM and spleen tissue was compensated at day 2 by the pro-proliferative effect of G-CSF. Furthermore, as evidenced by histological examination of BM sections at day 4, egress of haematopoietic cells from BM was accelerated by 2 days as compared to mobilization by G-CSF or CY alone; also, by day 6 there was accumulation of early haematopoietic (Thy-l(low) c-kit+) cells in the spleens and livers of mobilized animals. This implies that HSPC that are mobilized from BM and circulate in PB may 'home' to peripheral organs. We envision that such an accumulation of these cells in the spleen (which is a major haematopoietic organ in mouse) allows them to participate in haematopoietic reconstitution. Their homing to other sites (for example the liver) is evidence that BM-derived stem cells are playing a pivotal role in organ/tissue regeneration. The potential involvement of major chemoattractants for stem cells, like stromal-derived factor-1 which is induced by CY in various regenerating organs such as the liver, requires further study. We conclude that inclusion of CY into mobilization protocols on the one hand efficiently increases the egress of HSPC from the BM, but on the other hand may lead to the relocation of BM stem cell pools to peripheral tissues.

Effect of selenium and vitamin E on the development of experimental atherosclerosis in rabbits.

Male mongrel rabbits, divided into 5 groups (1) controls, (2) animals receiving a high-fat diet (HFD) containing cholesterol and coconut oil, (3) HFD + selenium, (4) HFD + vitamin E, (5) HFD + selenium + vitamin E, were treated for 12 weeks. In the groups receiving selenium and/or vitamin E, the elevation of serum total lipids, beta-lipoproteins, total cholesterol and triglyceride was markedly suppressed. HDL cholesterol in these groups of animals was increased. The cytochrome P-450 content in liver microsomes was increased, and the concentration of malondialdehyde in the blood plasma of rabbits was significantly decreased, while thyroid hormones (T4, T3), cortisol and insulin level were increased. Surface area of the lipid deposits at 12 weeks measured planimetrically averaged 76% in HFD-fed animals but only 28% in selenium + vitamin E treated rabbits. The important finding of this study is that combination of selenium and vitamin E, results in an intensified effect on the improvement of metabolic processes and on the reduction of atherosclerotic plaque formation.

Essential phospholipids modify immunological functions and reduce experimental atherosclerosis in rabbits.

Atherosclerosis was induced in male mongrel rabbits with a high-fat diet and the influence of essential phospholipids (EPL) on plaque formation, parameters of lipid metabolism and immunological functions was studied. When EPL were added to the high-fat diet there was a significant reduction in the area of atherosclerotic involvement of the aorta. The serum concentration of lipids decreased, often to normal values, and cholesterol esterified with polyunsaturated fatty acids appeared. Normalization of the malonyldialdehyde level in plasma was accompanied by a decrease in the concentration of ascorbate free radicals in blood and liver. The high-fat diet caused a depression of both non-specific and specific immune functions studied. With EPL in the diet the tests showed near normal or normal values. It is inferred from these results that a normal state of the immune system is important for preventing the progress of atherosclerotic changes. This is discussed with reference to the role of some immune cells in the metabolism of lipids and to participation of essential phospholipids in plasma membrane functions.

Pharmacokinetics of phenazone (antipyrine) in rabbits with experimental common bile duct obstruction.

1. An altered functional state of liver due to experimental cholestasis could result in a change in the biotransformation of drugs. The aim of this study was to evaluate an influence of obstructive cholestasis on the pharmacokinetics of phenazone (antipyrine). 2. The investigation was carried out on male rabbits, randomly allocated into two groups: shamoperated and animals with biliary ducts ligation. Phenazone was administered intragastrically as a probe of drug metabolism. 3. Measurements, i.e. laboratory and pharmacodynamic tests, as well as pharmacokinetic assays, were performed before the operation as well as 10-12 days after the bile duct ligation. At the end of the study livers were examined macro- and microscopically and biochemical analysis of the liver microsomes was performed. 4. The measured pharmacokinetic parameters suggested an impaired biotransformation of phenazone in animals with obstructive cholestasis, leading to a slower drug elimination.

Inducible nitric oxide synthase in the epithelial epididymal cells of the rat.

The expression of mRNA for inducible nitric oxide synthase (iNOS) in rat epithelial cells of epididymis was investigated with reverse transcription followed by polymerase chain reaction. Immunocytochemical reaction for iNOS was performed to confirm the enzyme's localization in the epididymal epithelium. Additionally, an indirect spectrophotometric method for nitric oxide (NO) determination was applied for measurement of nitrite production by cultured epididymal epithelial cells. Inducible NOS mRNA was detected in freshly isolated epithelial cells, in cultured cells without stimulation as well as in cultured cells after stimulation by lipopolysaccharide and interferon-gamma. Inducible NOS immunoreactivity was observed in the apical part of epithelial cells of epididymal sections and in the cytoplasm of cells in culture. Release of nitrite was observed in vitro in both the unstimulated and stimulated cells of caput (1.44+/-0.94 v. 4.37+/-2.42 microM) and cauda (0.69+/-1.21 v. 5.21+/-2.76 microM) epididymis (P < 0.001). To the best of our knowledge, this is the first study to demonstrate iNOS in the epididymal epithelial cells of the rat. Nitric oxide released by epididymal epithelial cells may act on cells and tissues located nearby. The results may help explain epididymal function: sperm storage, passage and maturation. Excessive epididymal NO production may also play a role in the inflammatory infertility of the male.

Steroidogenic characteristics of in vitro cultured epididymal epithelial cells of the rat.

The paper presents the steroidogenic features of cultured epithelial cells of rat epididymis and their ability to synthesize steroid hormones. The cytoplasm of epididymal epithelial cells accumulated lipid droplets and contained active enzymes of steroidogenesis. Numerous mitochondria with lamellar cristae occurred near lipid droplets. Frequently, mitochondria formed a direct contact with lipid droplets and smooth endoplasmic reticulum. The hormone assay showed that the epididymal epithelial cells cultured without dihydrotestosterone synthesized and released the following steroids: dehydroepiandrosterone (DHEA), testosterone (T) and 17beta-estradiol (E). The levels of DHEA and T were very low. The concentration of E detected in media of cultured epididymal epithelial cells exceeded many times the concentration of E in control media. The cytoplasmic presence of organelles and enzymes that participated in the steroid synthesis indicated their similarity to steroidogenic cells. Epididymal epithelial cells were capable of moderate in vitro synthesis of androgens. It cannot be excluded that steroidogenesis in the cultured epididymal epithelial cells is maintained to sustain 17beta-estradiol synthesis pathways.

In vivo and in vitro studies on the toxicity of Hoechst 33342 (Ho342). Implications for employing Ho342 for the isolation of haematopoietic stem cells.

The fluorescence dye Hoechst 33342 (Ho342) is employed for isolating early haematopoietic cells and the aim of this study was to evaluate the in vivo and in vitro toxicity of this compound. First, by employing a murine model we studied the influence of this dye on the morphology of the different organs of animals that have been injected intravenously with increasing doses of Ho342. Accordingly, we found that Ho342 at relatively low doses (0,3 M) caused morphological changes in the spleen and lungs and at higher doses (1,5 & 6 M) damaged also the liver. In contrast, kidneys appear to be relatively resistant to this dye. Next, since Ho342 is employed for isolating early haematopoietic cells by FACS, we have been looking for potential toxicity of this dye against normal human haematopoietic progenitors. Accordingly, CD34+ cells isolated from cord blood (CB) samples were exposed to increasing doses of Ho342 (0-50 microM). We found that the low concentration of Ho342 (10 microM) recommended for isolating HSC significantly inhibited the clonogenecity of human erythroid progenitors (BFU-E). The higher doses of Ho342 have also been toxic against normal human myeloid progenitors (CFU-GM). This study shows that Ho342 could potentially damage human cells. This fact should be considered whenever Ho342 has to be employed for isolating living cells.

Ultrastructure of spermatozoa from the cauda epididymis in rat chronically treated with lead acetate [Pb(II)].

Electron microscopic studies were performed on spermatozoa from the lumen of cauda epididymis in rats receiving lead acetate (II) for a period 5-fold longer than one spermatogenesis. There were numerous ultrastructural changes of spermatozoa. Mitochondrial spiral, outer dense fibers and axoneme were affected. Based on the present results it may be suggested that lead can damage spermatozoa in the epididymis.

Extractum Fagopyri reduces atherosclerosis in high-fat diet fed rabbits.

A group of 30 male mongrel rabbits was divided into 3 subgroups: controls, animals receiving a high-fat diet (HFD) containing cholesterol and coconut oil, HFD + Extr. Fagopyri (EF) were treated for 12 weeks. Surface areas of lipid deposites after 12 weeks of treatment measured planimetrically in the intima of the aorta, averaged 86.5% in HFD-fed animals, but 68.6% in EF treated rabbits. The positive effect of EF was confirmed histopathologically. The finding of this study is that the EF administration results in the reduction of atherosclerotic plaque formation.

Pharmacokinetics of lidocaine and its major metabolite- monoethylglycinexylidide (MEGX) in rabbits with experimental common bile duct obstruction.

The aim of this study was to evaluate, using an experimental model, the effect of obstructive cholestasis on the pharmacokinetics of lidocaine and the formation rate of its major metabolite- monoethylglycinexylidide (MEGX)-in rabbits. The investigation was carried out on 20 rabbits, randomly divided into two groups: a control one sham-operated and an experimental one-animals with biliary duct ligation. The measurements, i.e. laboratory and pharmacodynamic tests, as well as pharmacokinetic assays were performed prior to the operation as well as 10-12 days after the bile duct ligation. At the end stage of the study, livers were examined macro- and microscopically and biochemical analysis of the liver microsomes were performed. Lidocaine was given intravenously, as a bolus of 6 mg/kg. Blood for pharmacokinetic assay was sampled within 6 h following the drug administration, and MEGX concentration was evaluated 15 min after lidocaine had been administered. The immunofluorescence polarization method was employed for determination of lidocaine and MEGX concentrations. The one-compartment open model was used for calculations.

Phospholipid content and lamellar structures in the epididymal epithelial cells of rats treated chronically with lead acetate [Pb(II)].

The electron-microscopic observations accomplished covered epididymal epithelial cells of rats receiving lead acetate for five times longer than the duration of one spermatogenesis. These cells were found to possess a large number of vacuoles and conglomerates containing plicated membranes or tightly packed myelin-like lamellar formations. Further observations also revealed the formation of lamellar structures in mitochondria, dilatation of cisternae in the Golgi apparatus, and increased phagocytosis of spermatozoa by epithelial cells. The presence of a large amount of membranous material correlated with the increased content of phospholipids in epididymal epithelial cells. It may be suggested that the presence of such a great quantity of lamellar structures in epididymal epithelial cells of rats treated chronically with lead is the result of several processes, including the augmented synthesis of membranes associated with encircling the deposits of lead, autophagy in the cells, as well as intensified phagocytosis of spermatozoa.

[Histological evaluation of the elements of elastic fibers of the rabbit skin after administration of 30% elastin preparation]. / Ocena histologiczna elementów wlókien sprezystych skóry wlasciwej królików po stosowaniu preparatu z 30% elastyna.

The performed evaluation covers the elastic fibre elements in the dermis of rabbits after the preparation of 30% elastin in propylene glycol was rubber in. Moreover, the effect of elastin on the degree of proliferation of fibroblasts, isolated from the rabbit's skin, was determined in vitro. It has been found out that the used preparation exerts a stimulating effect on elastogenesis, but no differences in the degree of proliferation of the fibroblasts under in vitro condition were observed.

Perinatal exposure to lead induces morphological, ultrastructural and molecular alterations in the hippocampus.

The aim of this paper is to examine if pre- and neonatal exposure to lead (Pb) may intensify or inhibit apoptosis or necroptosis in the developing rat brain. Pregnant experimental females received 0.1% lead acetate (PbAc) in drinking water from the first day of gestation until weaning of the offspring; the control group received distilled water. During the feeding of pups, mothers from the experimental group were still receiving PbAc. Pups were weaned at postnatal day 21 and the young rats of both groups then received only distilled water until postnatal day 28. This treatment protocol resulted in a concentration of Pb in rat offspring whole blood (Pb-B) below the threshold of 10 µg/dL, considered safe for humans.We studied Casp-3 activity and expression, AIF nuclear translocation, DNA fragmentation, as well as Bax, Bcl-2 mRNA and protein expression as well as BDNF concentration in selected structures of the rat brain: forebrain cortex (FC), cerebellum (C) and hippocampus (H). The microscopic examinations showed alterations in hippocampal neurons.Our data shows that pre- and neonatal exposure of rats to Pb, leading to Pb-B below 10 µg/dL, can decrease the number of hippocampus neurons, occurring concomitantly with ultrastructural alterations in this region. We observed no morphological or molecular features of severe apoptosis or necrosis (no active Casp-3 and AIF translocation to nucleus) in young brains, despite the reduced levels of BDNF. The potential protective factor against apoptosis was probably the decreased Bax/Bcl-2 ratio, which requires further investigation. Our findings contribute to further understanding of the mechanisms underlying Pb neurotoxicity and cognition impairment in a Pb-exposed developing brain.