Evidence of a subcommissural organ involvement in the brain response to lead exposure and a modulatory potential of curcumin

Biomimetic Antidote Nanoparticles: a Novel Strategy for Chronic Heavy Metal Poisoning

Chronic lead poisoning has become a major factor in global public health. Chelation therapy is usually used to manage lead poisoning. Dimercaptosuccinic acid (DMSA) is a widely used heavy metal chelation agent. However, DMSA has the characteristics of poor water solubility, low oral bioavailability, and short half-life, which limit its clinical application. Herein, a long-cycle slow-release nanodrug delivery system was constructed. We successfully coated the red blood cell membrane (RBCM) onto the surface of dimercaptosuccinic acid polylactic acid glycolic acid copolymer (PLGA) nanoparticles (RBCM-DMSA-NPs), which have a long cycle and detoxification capabilities. The NPs were characterized and observed by particle size meters and transmission electron microscopy. The results showed that the particle size of RBCM-DMSA-NPs was approximately 146.66 ± 2.41 nm, and the zeta potential was - 15.34 ± 1.60 mV. The homogeneous spherical shape and clear core-shell structure of the bionic nanoparticles were observed by transmission electron microscopy. In the animal tests, the area under the administration time curve of RBCM-DMSA-NPs was 156.52 ± 2.63 (mg/L·h), which was 5.21-fold and 2.36-fold that of free DMSA and DMSA-NPs, respectively. Furthermore, the median survival of the RBCM-DMSA-NP treatment group (47 days) was 3.61-fold, 1.32-fold, and 1.16-fold for the lead poisoning group, free DMSA, and DMSA-NP groups, respectively. The RBCM-DMSA-NP treatment significantly extended the cycle time of the drug in the body and improved the survival rate of mice with chronic lead poisoning. Histological analyses showed that RBCM-DMSA-NPs did not cause significant systemic toxicity. These results indicated that RBCM-DMSA-NPs could be a potential candidate for long-term chronic lead exposure treatment.

Study of the neurochemical alterations produced by acute and subchronic Pb-exposure in Meriones shawi: Immunohistochemical study of Reissner's fiber secretion by the subcommissural organ after curcumin-III treatment

BACKGROUND

Lead neurotoxicity is associated with numerous alterations including behavioral and neurochemical disruptions. This study evaluates the possible neurochemical disruption in the subcommissural organ (SCO) after acute (three days) and subchronic (six weeks) Pb-exposure inMeriones shawi, and the possible effect of the third active compound, curcumin-III, in mitigating the neurological alterations caused by lead exposure.

METHODS

Using immunohistochemical stainings, we evaluated the Reissner's fiber (RF) secretion utilizing RF-antibody in the SCO. We compared both acute (25 mg/kg bw of Pb i.p. for 3 days) and subchronic (3 g/l of Pb in drinking water for six weeks) Pb-treatedMeriones shawi.

RESULTS

The two models of lead exposure showed a significant increase in RF level in the SCO. Conversely, co-treatment with Curcumin-III at a dose of 30 mg/kg bw significantly ameliorate SCO secretory activity, as revealed by decreased RF-immunoreactivity.

CONCLUSION

Together, our findings suggest the protective effects of Curcumin-III in regulating the secretory activity of the SCO after Pb-induced neuroanatomical disruptions of the SCO in Meriones.

Physiological Alterations of Subchronic Lead Exposure Induced Degeneration of Epithelial Cells in Proximal Tubules and the Remedial Effect of Curcumin-III in Meriones shawi: a Possible Link with Vasopressin Release

At the industrial working conditions, lead exposure could induce several alterations for the human body. Subchronic lead exposure is linked with several injuries including cerebral and renal dysfunctions. The present work discusses the effects of subchronic lead toxicity (3 g/l) in drinking water during the period of treatment (6 weeks) on vasopressin system and epithelial cells in proximal tubules. Also, we aimed to evaluate the protective effect of curcumin-III administered orally by gavage (30 mg/kg BW), against subchronic Pb exposure in Meriones shawi. The biochemical and histopathological examinations demonstrate renal damages induced by lead toxicity. In addition, the behavioral and immunohistochemical studies revealed that Pb neurotoxicity exhibited an anxious behavior with a significant elevation of the vasopressin (AVP) staining within the paraventricular nuclei. The study showed also curcumin-III restored the renal alterations with an anxiolytic effect. Moreover, it restored the AVP level in the studying nuclei. Our work supports a possible link between AVP release and epithelial degeneration in the proximal tubules, and shows a new pharmacological effect of curcumin-III as an anxiolytic agent against lead toxicity.

SCO-spondin, a giant matricellular protein that regulates cerebrospinal fluid activity

Cerebrospinal fluid is a clear fluid that occupies the ventricular and subarachnoid spaces within and around the brain and spinal cord. Cerebrospinal fluid is a dynamic signaling milieu that transports nutrients, waste materials and neuroactive substances that are crucial for the development, homeostasis and functionality of the central nervous system. The mechanisms that enable cerebrospinal fluid to simultaneously exert these homeostatic/dynamic functions are not fully understood. SCO-spondin is a large glycoprotein secreted since the early stages of development into the cerebrospinal fluid. Its domain architecture resembles a combination of a matricellular protein and the ligand-binding region of LDL receptor family. The matricellular proteins are a group of extracellular proteins with the capacity to interact with different molecules, such as growth factors, cytokines and cellular receptors; enabling the integration of information to modulate various physiological and pathological processes. In the same way, the LDL receptor family interacts with many ligands, including β-amyloid peptide and different growth factors. The domains similarity suggests that SCO-spondin is a matricellular protein enabled to bind, modulate, and transport different cerebrospinal fluid molecules. SCO-spondin can be found soluble or polymerized into a dynamic threadlike structure called the Reissner fiber, which extends from the diencephalon to the caudal tip of the spinal cord. Reissner fiber continuously moves caudally as new SCO-spondin molecules are added at the cephalic end and are disaggregated at the caudal end. This movement, like a conveyor belt, allows the transport of the bound molecules, thereby increasing their lifespan and action radius. The binding of SCO-spondin to some relevant molecules has already been reported; however, in this review we suggest more than 30 possible binding partners, including peptide β-amyloid and several growth factors. This new perspective characterizes SCO-spondin as a regulator of cerebrospinal fluid activity, explaining its high evolutionary conservation, its apparent multifunctionality, and the lethality or severe malformations, such as hydrocephalus and curved body axis, of knockout embryos. Understanding the regulation and identifying binding partners of SCO-spondin are crucial for better comprehension of cerebrospinal fluid physiology.

Subcommissural organ-Reissner's fiber complex plasticity in two animal models of copper intoxication and modulatory effect of curcumin: Involvement of serotonin

Metal neurotoxicity is a universal health preoccupation. Previous data revealed an obvious neurochemical impairment induced by metal elements as copper. This investigation was conducted to study the subcommissural organ (SCO) response to acute and subchronic Cu exposure as well as its serotoninergic innervation in Wistar rats, and the probable protective potential of curcumin in these toxicological circumstances. By mean of immunohistochemistry using antibodies against Reissner's fiber (RF) and serotonin (5-HT) in acute model (10 mg/kg i.p. for 3 days) and subchronic model (0.125% in drinking water for six weeks), we noted a significant decrease of RF-immunoreactivity and a whole amplified 5-HT innervation of SCO and ventricular borders in intoxicated rats. Co-treatment with curcumin-I (30 mg/kg B.W) has shown a beneficial effect, reinstating both SCO secretory activity and serotoninergic innervation damaged by Cu exposure. This data revealed for the first time an obvious response of SCO-RF complex to Cu intoxication as well as the neuroprotective effect of curcumin-I. Thus, SCO could play a fundamental role in the strategies of brain resistance to neurotoxicity induced by metal elements in rats, and may be used as biomarker to assist in the diagnosis of this neurotoxicological conditions in rodents.

Neuronal, astroglial and locomotor injuries in subchronic copper intoxicated rats are repaired by curcumin: A possible link with Parkinson's disease

We aim herein to assess the neurotoxic effects of subchronic Cu-exposition (0125%) for 6 weeks on dopaminergic and astroglial systems then locomotor activity in rats as well as the probable therapeutic efficiency of curcumin-I (30 mg/kg B.W.). We found that intoxicated rats showed a significant impairment of Tyrosine Hydroxylase (TH) within substantia nigra pars compacta (SNc), ventral tegmental area (VTA) and the striatal outputs together with loss expression of GFAP in these structures. This was linked with an evident decrease in locomotor performance. Co-treatment with curcumin-I inverted these damages and exhibited a significant neuroprotective potential, thus, both TH expression and locomotor performance was reinstated in intoxicated rats. These results prove a profound dopaminergic and astroglial damages following subchronic Cu exposition and new beneficial curative potential of curcumin against subchronic Cu-induced astroglial and dopaminergic neurotoxicity. Consequently, we suggest that Cu neurotoxicity may be strengthened in vivo firstly by attacking and weaking the astroglial system, and curcumin could be prized as a powerful and preventive target for the neurodegenerative diseases related metal element, especially Parkinson's disease.