PRP-1 Protective Effect against Central and Peripheral Neurodegeneration following n. ischiadicus Transection

Morpho‑functional study of the hypothalamic proline‑rich polypeptide apoptotic activity against mouse Ehrlich ascites carcinoma

A new type of bioactive polypeptides of the neurosecretory hypothalamus called proline‑rich peptides (PRPs), which are isolated from bovine neurosecretory granules of the neurohypophysis, are synthesized in the form of a common precursor protein (neurophysin vasopressin‑associated glycoprotein). Proline‑rich polypetide 1 (PRP‑1; also known as galarmin) is comprised of 15 amino acids residues, and has been suggested to possess anti‑neurodegenerative, immunoregulatory, hematopoietic, antimicrobial and antitumor properties. The cytostatic, antiproliferative effect of PRP‑1 was demonstrated in the human chondrosarcoma JJ012 and triple negative breast carcinoma MDA MB 231 cell lines. PRP‑1 action is disease and tissue specific. To further explore the antitumorigenic and possible cytotoxic effects of PRP‑1, a morpho‑functional study on the effect of PRP‑1 on a mouse Ehrlich ascites carcinoma (EAC) model was conducted. The PRP‑1‑induced morphological features of EAC cells confirmed the apoptotic nature of PRP‑1, as manifested by cell shrinkage, membrane blebbing, chromosome condensation (pyknosis) and nuclear fragmentation (karyorrhexis). The effect of PRP‑1 on the number of tumor cells incubated for 24 h and their viability in trypan blue‑stained samples lead to a 44% reduction in the number of viable cells on day 11 post‑inoculation vs. 22% inhibition of viable cells after PRP‑1 treatment (0.1 µg/ml) on day 7 post‑inoculation. Apoptosis experiments using an Annexin V‑cyanine 3 apoptosis detection kit indicated that 24 h incubation with 0.1 µg/ml PRP‑1 caused a significant increase in the number of apoptotic cells, reaching 50.33%, compared to 8.33% in the sample control on day 7 post‑inoculation.

Concepts of neuroendocrine cardiology and neuroendocrine immunology, chemistry and biology of signal molecules

Discovery of neurosecretion of cardioactive neurohormones produced by hypothalamic nuclei (NSO and NPV), as well as the biosynthesis of several immunomodulators (signal molecules of the neuroendocrine immune system of brain), deciphering of their chemical structure and study of their biological properties led to the foundation of two important trends of neurobiology: neuroendocrine immunology and cardiology. Hormone formation by atrium ganglionary nerve cells and auriculum establishment of neurohumoral interactions between hypothalamic and atrium neurosecretion indicated the existence of the system neuroendocrine hypothalamus--endocrine heart. Study of their biological properties promoted creation of powerful neurohormonal preparations for the treatment of immune, cardio-vascular, neurodegenerative, infectious and tumor diseases. Concepts suggested by us on neuroendocrine cardiology and immunology, create large perspectives for development of the theory and its implementation in medicine.

Hypothalamic proline rich polypeptide regulates hematopoiesis

The AGAPEPAEPAQPGVY proline-rich polypeptide (PRP-1) was isolated from neurosecretory granules of the bovine neurohypophysis; it is produced by N. supraopticus and N. paraventricularis. It has been shown that PRP-1 has many potentially beneficial biological effects including immunoregulatory, hematopoietic, antimicrobial and anti-neurodegenerative properties. Here we demonstrated that PRP-1 administration influence on redistribution of monocytes, granulocytes and lymphocytes between bone marrow (BM) and peripheral blood and promotes the influx of granulocytes and monocytes/macrophages from BM into peripheral blood and accumulation of immature granulocyte and monocyte in BM and delayed the maturation of T cells in BM. PRP-1 increased colony-forming cell proliferation in rat cells in vivo. In PRP-treated rat BM, the CFU number at day 4, 7 and 14 was considerably increased in comparison with untreated rats BM and no difference was found at day 21 and day 28. We found that PRP-1 enhances erythroid and myeloid colonies formation in human CD34(+) progenitor cell culture in the presence of different growth factors and down-regulates T cells colony formation and specific surface markers expression during induction of human CD34(+) progenitor cells differentiation into T lymphocytes lineage. We suggested that the hypothalamic PRP-1 possibly represents an endogenous peptide whose primary functions are to regulate neuronal survival and differentiation and hematopoiesis within neurosecretory hypothalamus-bone marrow humoral axis.

Neuroprotection by hypothalamic peptide proline-rich peptide-1 in Abeta25-35 model of Alzheimer's disease

BACKGROUND

This work sought to determine the effects of hypothalamic proline-rich peptide (PRP)-1 in a rat model of Alzheimer's disease.

METHODS

Complex histochemical, electrophysiologic, and behavioral analyses were performed on intact or diseased Wistar rats (n = 28). Pathologic conditions were induced by bilateral intracerebroventricular injection of amyloid peptide Abeta25-35. The diseased rats received systemic administration of PRP-1 or placebo control.

RESULTS

Abeta25-35 caused cellular neurodegeneration with marked glial reaction in the hippocampal complex and almost full destruction of the dentate fascia, which was not observed in conditions of PRP-1 administration after Abeta25-35 injection. Hippocampal neurons of intact animals responded to high-frequency (tetanic) stimulation of entorhinal cortex of ipsilateral cerebral hemisphere by tetanic and posttetanic potentiation of a different intensity and duration, which was accompanied by posttetanic depression. Abeta25-35 led to significant changes in the level and pattern of hippocampal neuronal activity, indicating the absence of both tetanic and posttetanic activity. Poststimulus activity manifestations rarely occurred and rapidly decreased after repeated trials. This indicated the focal character of lesion. Regular administration of PRP-1 for 4 weeks resulted in optimal restoration of electrophysiologic parameters. PRP-1 maintained the initial learning level achieved in a behavioral study in a Morris water maze.

CONCLUSIONS

Systemic administration of PRP-1 possesses neuroprotective effects and can prevent the neurodegeneration in hippocampus induced by Abeta25-35. This suggests that PRP-1 could be a potential therapeutic agent for specific neurodegenerative diseases.

Syncytial coupling of neurons in tissue culture and early ontogenesis

Computerized time-lapse video recording was used to detect the process of formation of syncytial couplings between the processes of different neurons in dissociated neuron cultures. These studies showed that once the processes of one neuron had formed connections with another neuron, death of the cell body (its trophic center) was not followed by Wallerian degeneration. Translocation of cytoplasmic varicosities along the branches of one neuron to another was observed over periods of several hours. Electron microscopic studies of the nerve processes of cells in the intramural intestinal plexus in the early postnatal period demonstrated all the transitional states from fusion and perforation of the membranes of contacting dendrites to complete fusion of the neuroplasm of processes with formation of residual membranous structures at the location of the former intercellular contact.

Proline-rich polypeptides in Alzheimer's disease and neurodegenerative disorders -- therapeutic potential or a mirage?

The development of effective and safe drugs for a growing Alzheimer disease population is an increasing need at present. Both experimental and clinical evidence support a beneficial effect of proline-rich polypeptides in a number of neurodegenerative diseases, including Alzheimer disease. Experimental data have shown that proline-rich polypeptides isolated from bovine neurohypophisis possess neuroprotective and neuromodulatory properties in mice with aluminum neurotoxicosis or neuronal damage caused by venoms and toxins. Proline-rich polypeptides from ovine colostrums, so called Colostrinin, have been shown to produce cognitive improvement in an experimental model and in patients with Alzheimer disease. However, the precise mechanism underlying the neuroprotective action of proline-rich polypeptides is not very well established. Moreover, studies pointing at a neuroprotective effect of proline-rich polypeptides from bovine neurohypophisis in humans have not been reported thus far. The authors conclude that more detailed information on the mode of action of proline-rich polypeptides is needed as well as confirmation of their efficacy in broad clinical trials before this approach can really show its potential in the treatment of neurodegenerative disorders.

Hyperbaric oxygenation in peripheral nerve repair and regeneration

Peripheral nerves are essential connections between the central nervous system and muscles, autonomic structures and sensory organs. Their injury is one of the major causes for severe and longstanding impairment in limb function. Acute peripheral nerve lesion has an important inflammatory component and is considered as ischemia-reperfusion (IR) injury. Surgical repair has been the standard of care in peripheral nerve lesion. It has reached optimal technical development but the end results still remain unpredictable and complete functional recovery is rare. Nevertheless, nerve repair is not primarily a mechanical problem and microsurgery is not the only key to success. Lately, there have been efforts to develop alternatives to nerve graft. Work has been carried out in basal lamina scaffolds, biologic and non-biologic structures in combination with neurotrophic factors and/or Schwann cells, tissues, immunosuppressive agents, growth factors, cell transplantation, principles of artificial sensory function, gene technology, gangliosides, implantation of microchips, hormones, electromagnetic fields and hyperbaric oxygenation (HBO). HBO appears to be a beneficial adjunctive treatment for surgical repair in the acute peripheral nerve lesion, when used at lower pressures and in a timely fashion (<6 hours).

Effect of Hypothalamic Proline-Rich Peptide (PRP-1) on Neuronal and Bone Marrow Cell Apoptosis

The AGAPEPAEPAQPGVY proline-rich peptide (PRP-1) was isolated from neurosecretory granules of the bovine neurohypophysis; it is produced by N. supraopticus and N. paraventricularis. It has been shown that PRP-1 has many potentially beneficial biological effects including immunoregulatory, hematopoietic, antimicrobial and anti-neurodegenerative properties. Here we investigated the influence of PRP-1 on staurosporine-induced apoptosis of postnatal hippocampal cells and on doxorubicin-induced bone marrow granulocyte- and monocyte apoptosis. The intention was to further characterize the effect of PRP-1 on the survival rate of neurons and in context with myelopoiesis. We demonstrate that PRP-1 significantly reduced apoptosis of postnatal hippocampal cells induced by staurosporine. The protective effect of PRP-1 against apoptotic cell death was shown to be both time- and dose-dependent. Neuroprotection was more pronounced after prolonged pretreatment of the cells with PRP-1 before the induction of apoptosis with staurosporine. The related peptide [arg(8)]vasopressin did not reveal neuroprotection. PRP-1 also significantly reduced apoptosis of bone marrow monocytes and granulocytes induced by doxorubicin. This protective effect lasted for 2-4 h and was not detectable anymore after 24 h when PRP-1 and doxorubicin were added simultaneously. Previously obtained data and results of the current studies suggested that the hypothalamic PRP-1 possibly represents an endogenous peptide whose primary functions are to regulate myelopoiesis and neuron survival as we provide evidence that PRP can differentially reduce both staurosporine- and doxorubicin-induced hippocampal and bone marrow cell apoptosis.