Attenuation of kindled seizures by intranasal delivery of neuropeptide-loaded nanoparticles

Biopolymers as promising vehicles for drug delivery to the brain

The brain is a privileged organ, tightly guarded by a network of endothelial cells, pericytes, and glial cells called the blood brain barrier. This barrier facilitates tight regulation of the transport of molecules, ions, and cells from the blood to the brain. While this feature ensures protection to the brain, it also presents a challenge for drug delivery for brain diseases. It is, therefore, crucial to identify molecules and/or vehicles that carry drugs, cross the blood brain barrier, and reach targets within the central nervous system. Biopolymers are large polymeric molecules obtained from biological sources. In comparison with synthetic polymers, biopolymers are structurally more complex and their 3D architecture makes them biologically active. Researchers are therefore investigating biopolymers as safe and efficient carriers of brain-targeted therapeutic agents. In this article, we bring together various approaches toward achieving this objective with a note on the prospects for biopolymer-based neurotherapeutic/neurorestorative/neuroprotective interventions. Finally, as a representative paradigm, we discuss the potential use of nanocarrier biopolymers in targeting protein aggregation diseases.

Changes in the Dentate Gyrus Gene Expression Profile Induced by Levetiracetam Treatment in Rats with Mesial Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is one of the most common forms of focal epilepsy. Levetiracetam (LEV) is an antiepileptic drug whose mechanism of action at the genetic level has not been fully described. Therefore, the aim of the present work was to evaluate the relevant gene expression changes in the dentate gyrus (DG) of LEV-treated rats with pilocarpine-induced TLE. Whole-transcriptome microarrays were used to obtain the differential genetic profiles of control (CTRL), epileptic (EPI), and EPI rats treated for one week with LEV (EPI + LEV). Quantitative RT-qPCR was used to evaluate the RNA levels of the genes of interest. According to the results of the EPI vs. CTRL analysis, 685 genes were differentially expressed, 355 of which were underexpressed and 330 of which were overexpressed. According to the analysis of the EPI + LEV vs. EPI groups, 675 genes were differentially expressed, 477 of which were downregulated and 198 of which were upregulated. A total of 94 genes whose expression was altered by epilepsy and modified by LEV were identified. The RT-qPCR confirmed that LEV treatment reversed the increased expression of Hgf mRNA and decreased the expression of the Efcab1, Adam8, Slc24a1, and Serpinb1a genes in the DG. These results indicate that LEV could be involved in nonclassical mechanisms involved in Ca2+ homeostasis and the regulation of the mTOR pathway through Efcab1, Hgf, SLC24a1, Adam8, and Serpinb1a, contributing to reduced hyperexcitability in TLE patients.

Nanotechnological advances in the treatment of epilepsy: a comprehensive review

Epilepsy is one of the most prevalent chronic neurological disorders characterized by frequent unprovoked epileptic seizures. Epileptic seizures can develop from a broad range of underlying abnormalities such as tumours, strokes, infections, traumatic brain injury, developmental abnormalities, autoimmune diseases, and genetic predispositions. Sometimes epilepsy is not easily diagnosed and treated due to the large diversity of symptoms. Undiagnosed and untreated seizures deteriorate over time, impair cognition, lead to injuries, and can sometimes result in death. This review gives details about epilepsy, its classification on the basis of International League Against Epilepsy, current therapeutics which are presently offered for the treatment of epilepsy. Despite of the fact that more than 30 different anti-epileptic medication and antiseizure drugs are available, large number of epileptic patients fail to attain prolonged seizure independence. Poor onsite bioavailability of drugs due to blood brain barrier poses a major challenge in drug delivery to brain. The present review covers the limitations with the state-of-the-art strategies for managing seizures and emphasizes the role of nanotechnology in overcoming these issues. Various nano-carriers like polymeric nanoparticles, dendrimers, lipidic nanoparticles such as solid lipid nanoparticles, nano-lipid carriers, have been explored for the delivery of anti-epileptic drugs to brain using oral and intranasal routes. Nano-carries protect the encapsulated drugs from degradation and provide a platform to deliver controlled release over prolonged periods, improved permeability and bioavailability at the site of action. The review also emphasises in details about the role of neuropeptides for the treatment of epilepsy.

Recent Advances in Delivery of Peptide and Protein Therapeutics to the Brain

The classes of neuropharmaceuticals known as proteins and peptides serve as diagnostic tools and are involved in specific communication in the peripheral and central nervous systems. However, due to tight junctions resembling epithelial cells found in the blood-brain barrier (BBB) in vivo, they are typically excluded from transport from the blood to the brain. The drugs having molecular weight of less than 400 Dalton are able to cross the BBB via lipid-mediated free diffusion. However, large molecule therapeutics are devoid of these characteristics. As an alternative, these substances may be carried via chimeric peptide drug delivery systems, and assist in transcytosis through BBB with the aid of linker strategies. With their recent developments, several forms of nanoparticles, including poly (ethylene glycol)-poly(ε-caprolactone) copolymers, nanogels, liposomes, nanostructured lipid carriers, poly (D, L-lactide-co-glycolide) nanoparticles, chitosan, and solid lipid nanoparticles, have also been considered for their therapeutic applications. Moreover, the necessity for physiologic optimization of current drug delivery methods and their carriers to deliver therapeutic doses of medication into the brain for the treatment of various neurologic illnesses has also been emphasized. Therapeutic use of proteins and peptides has no neuroprotective impact in the absence of all these methods. Each tactic, however, has unique drawbacks and considerations. In this review, we discuss different drug delivery methods for therapeutic distribution of pharmaceuticals, primarily neuroproteins and neuropeptides, through endothelial capillaries via blood-brain barrier. Finally, we have also discussed the challenges and future perspective of protein and peptide therapeutics delivery to the brain. SIGNIFICANCE STATEMENT: Very few reports on the delivery of therapeutic protein and peptide nanoformulations are available in the literature. Herein, we attempted to discuss these nanoformulations of protein and peptide therapeutics used to treat brain diseases.

Paclitaxel Delivery to the Brain for Glioblastoma Treatment

The development of paclitaxel-loaded polymeric nanoparticles for the treatment of brain tumors was investigated. Poly(lactide-glycolide) (PLGA) nanoparticles containing 10% w/w paclitaxel with a particle size of 216 nm were administered through intranasal and intravenous routes to male Sprague-Dawley rats at a dose of 5 mg/kg. Both routes of administration showed appreciable accumulation of paclitaxel in brain tissue, liver, and kidney without any sign of toxicity. The anti-proliferative effect of the nanoparticles on glioblastoma tumor cells was comparable to that of free paclitaxel.

New Efforts to Demonstrate the Successful Use of TRH as a Therapeutic Agent

Thyrotropin-releasing hormone (TRH) is a tripeptide that regulates the neuroendocrine thyroid axis. Moreover, its widespread brain distribution has indicated that it is a relevant neuromodulator of behaviors such as feeding, arousal, anxiety, and locomotion. Importantly, it is also a neurotrophic peptide, and thus may halt the development of neurodegenerative diseases and improve mood-related disorders. Its neuroprotective actions on those pathologies and behaviors have been limited due to its poor intestinal and blood-brain barrier permeability, and because it is rapidly degraded by a serum enzyme. As new strategies such as TRH intranasal delivery emerge, a renewed interest in the peptide has arisen. TRH analogs have proven to be safe in animals and humans, while not inducing alterations in thyroid hormones' levels. In this review, we integrate research from different approaches, aiming to demonstrate the therapeutic effects of TRH, and to summarize new efforts to prolong and facilitate the peptide's actions to improve symptoms and the progression of several pathologies.

Cell-Penetrating Peptides as Valuable Tools for Nose-to-Brain Delivery of Biological Drugs

Due to their high specificity toward the target and their low toxicity, biological drugs have been successfully employed in a wide range of therapeutic areas. It is yet to be mentioned that biologics exhibit unfavorable pharmacokinetic properties, are susceptible to degradation by endogenous enzymes, and cannot penetrate biological barriers such as the blood-brain barrier (i.e., the major impediment to reaching the central nervous system (CNS)). Attempts to overcome these issues have been made by exploiting the intracerebroventricular and intrathecal routes of administration. The invasiveness and impracticality of these procedures has, however, prompted the development of novel drug delivery strategies including the intranasal route of administration. This represents a non-invasive way to achieve the CNS, reducing systemic exposure. Nonetheless, biotherapeutics strive to penetrate the nasal epithelium, raising the possibility that direct delivery to the nervous system may not be straightforward. To maximize the advantages of the intranasal route, new approaches have been proposed including the use of cell-penetrating peptides (CPPs) and CPP-functionalized nanosystems. This review aims at describing the most impactful attempts in using CPPs as carriers for the nose-to-brain delivery of biologics by analyzing their positive and negative aspects.

Preclinical In-Vivo Safety of a Novel Thyrotropin-Releasing Hormone-Loaded Biodegradable Nanoparticles After Intranasal Administration in Rats and Primates

Thyrotropin-releasing hormone (TRH) and TRH-like peptides carry a therapeutic potential for neurological conditions. Nanoparticles (NP) made of the biodegradable polymer, Poly(Sebacic Anhydride) (PSA), have been developed to carry TRH, intended for intranasal administration to patients. There is limited information on the safety of biodegradable polymers when given intranasally, and therefore, we have performed two preclinical safety and toxicity studies in cynomolgus monkeys and rats using TRH-PSA nanoparticles. The rats and monkeys were dosed intranasally for 42 days or 28 days, respectively, and several animals were followed for additional 14 days. Animals received either placebo, vehicle (PSA), or different concentrations of TRH-PSA. No systemic adverse effects were seen. Changes in T3 or T4 concentrations were observed in some TRH-PSA-treated animals, which did not have clinical or microscopic correlates. No effect was seen on TSH or prolactin concentrations. In the monkey study, microscopic changes in the nasal turbinates were observed, which were attributed to incidental mechanical trauma caused during administration. Taken together, the TRH-loaded PSA NPs have proven to be safe, with no local or systemic adverse effects attributed to the drug loaded nanoparticles. These findings provide additional support to the growing evidence of the safety of peptide-loaded NPs for intranasal delivery and pave the way for future clinical trials in humans.

Translational Considerations in the Development of Intranasal Treatments for Epilepsy

Epilepsy is a common and serious neurological disorder, to which a high proportion of patients continue to be considered "drug-resistant", despite the availability of a host of anti-seizure drugs. Investigation into new treatment strategies is therefore of great importance. One such strategy is the use of the nose to deliver drugs directly to the brain with the help of pharmaceutical formulation to overcome the physical challenges presented by this route. The following review explores intranasal delivery of anti-seizure drugs, covering the link between the nose and seizures, pathways from the nose to the brain, current formulations in clinical use, animal seizure models and their proposed application in studying intranasal treatments, and a critical discussion of relevant pre-clinical studies in the literature.

Using nanotechnology to deliver biomolecules from nose to brain - peptides, proteins, monoclonal antibodies and RNA

There is a growing number of biomolecules, including peptides, proteins, monoclonal antibodies and RNA, that could be potentially used for the treatment of central nervous system (CNS) diseases. However, the realization of their potential is being hampered by the extraordinary difficulties these complex biomolecules have to reach the brain in therapeutically meaningful amounts. Nose-to-brain (N-to-B) delivery is now being investigated as a potential option for the direct transport of biomolecules from the nasal cavity to different brain areas. Here, we discuss how different technological approaches enhance this N-to-B transport, with emphasis on those that have shown a potential for clinical translation. We also analyse how the physicochemical properties of nanocarriers and their modification with cell-penetrating peptides (CPPs) and targeting ligands affect their efficacy as N-to-B carriers for biomolecules.

Nose-to-brain/spinal cord delivery kinetics of liposomes with different surface properties

The administration of liposomes via nose-to-brain delivery is expected to become a strategy for efficient drug delivery to the central nervous system. Efficient nose-to-brain delivery and the kinetics of drugs administered in this manner depend on the properties of liposomes. However, there is a lack of basic knowledge of which liposomes are suitable for this purpose. Here, a qualitative study of intranasally administered liposomes (positively charged, neutral, and negatively charged, with or without polyethylene glycol [PEG] modification; particle size <100 nm) was performed to elucidate their dynamics in the brain and spinal cord. Additionally, a quantitative investigation was performed to ascertain their distribution in each part of the brain and spinal cord. The effects of liposome surface charge and PEG modification on the kinetics and distribution post intranasal administration were investigated via two experiments. Qualitative evaluation was performed via ex vivo observation after intranasal administration of fluorescently labeled liposomes. Neutral PEG-modified liposomes were distributed throughout the brain and spinal cord 60 min after administration, and the fluorescence intensity increased with time. By contrast, non-PEG-modified neutral liposomes showed particularly strong fluorescence in the olfactory bulb, and the fluorescence was localized in the anterior part of the brain. Positively charged liposomes showed low fluorescence around the lateral part of the brain and lumbar spinal cord 60 min after administration. Low fluorescence was observed in the whole brain and spinal cord, with strong fluorescence being observed in the olfactory bulb after 120 min of administration. Negatively charged liposomes showed no fluorescence at 60 min after administration, but low fluorescence was observed throughout the brain and spinal cord 120 min after administration. We quantified the radioactivity in the brain and spinal cord after intranasal administration of radioisotope-labeled liposomes. Neutral liposomes showed the highest distribution by area under the drug concentration-time curve (AUC_(60-120)) in the brain and spinal cord compared to other liposomes. Compared with negatively charged liposomes, positively charged liposomes had a higher distribution in the olfactory bulb and forebrain, while negatively charged liposomes had a higher distribution in the hindbrain and bulbospinal tract cord. In addition, the distribution of PEG-modified neutral liposomes in the brain and spinal cord was significantly enhanced compared to that of non-PEG-modified neutral liposomes after 90 min of intranasal administration. These results indicate that surface charge and PEG modification strongly affect the efficiency of nose-to-brain delivery kinetics, and that PEG-modified neutral liposomes are excellent carriers for drug delivery to a wide area of the brain and spinal cord.

Nanotherapeutics for Nose-to-Brain Drug Delivery: An Approach to Bypass the Blood Brain Barrier

Treatment of neurodegenerative diseases or other central nervous system (CNS) disorders has always been a significant challenge. The nature of the blood-brain barrier (BBB) limits the penetration of therapeutic molecules to the brain after oral or parenteral administration, which, in combination with hepatic metabolism and drug elimination and inactivation during its journey in the systemic circulation, decreases the efficacy of the treatment, requires high drug doses and often induces adverse side effects. Nose-to-brain drug delivery allows the direct transport of therapeutic molecules by bypassing the BBB and increases drug concentration in the brain. The present review describes mechanisms of nose-to-brain drug delivery and discusses recent advances in this area with especial emphasis on nanotechnology-based approaches.

Intranasal delivery of phenytoin-loaded nanoparticles to the brain suppresses pentylenetetrazol-induced generalized tonic clonic seizures in an epilepsy mouse model

In this work we describe the preparation and characterization of lecithin-chitosan nanoparticles (L₁₀C_i⁺), and investigate their ability to deliver the anti-epileptic drug phenytoin (PHT) to mouse brain following intranasal (IN) administration. L₁₀C_i⁺ were retained in the nasal cavity compared to PHT in PEG200 solution (PHT/PEG), which suffered immediate nasal drainage. PHT was detected in the brain after 5 min of IN administration reaching a maximum of 11.84 ± 2.31 %ID g^-1 after 48 hours. L₁₀C_i⁺ were associated with a higher brain/plasma ratio (C_b/p) compared to the experimental control comprising free PHT injected via the intraperitoneal route (PHT-IP) across all tested time points. Additionally, L₁₀C_i⁺ led to lower PHT accumulation in the liver and spleen compared to PHT-IP, which is vital for lowering the systemic side effects of PHT. The relatively high drug targeting efficiency (DTE%) of 315.46% and the drug targeting percentage (DTP%) of 68.29%, combined with the increasing anterior-to-posterior gradient of PHT in the brain confirmed the direct nose-to-brain transport of PHT from L₁₀C_i⁺. Electroencephalogram (EEG) analysis was used to monitor seizure progression. L₁₀C_i⁺ resulted in a complete seizure suppression after 4 hours of administration, and this inhibition persisted even with an 8-fold reduction of the encapsulated dose compared to the required PHT-IP dose to achieve a similar inhibitory effect due to systemic loss. The presented findings confirm the possibility of using L₁₀C_i⁺ as a non-invasive delivery system of PHT for the management of epilepsy using reduced doses of PHT.

Management of epileptic disorders using nanotechnology-based strategies for nose-to-brain drug delivery

INTRODUCTION

Epilepsy, a major neurological disorder affects about 1% of the Indian population. The discovery of noninvasive strategies for epilepsy presents a challenge for the scientists. Different types of nose-to-brain dosage-forms have been studied for epilepsy management. It aims to give new perspectives for developing new and existing anti-epileptic drugs. Combining nanotechnology with nose-to-brain approach can help in promoting the treatment efficacy by site-specific delivery. Also, it will minimize the side-effects and patient noncompliance observed in conventional administration routes. Peptide delivery can be an interesting approach for the management of epilepsy. Drug-loaded intranasal nanoformulations exhibit diverse prospective potentials in the management of epilepsy. Considering that, nanotherapy using nose-to-brain delivery as a prospective technique for the efficient management of epilepsy is reviewed.

AREAS COVERED

The authors have compiled all recently available data pertaining to the nose-to-brain delivery of therapeutics using nanotechnological strategies. The fundamental mechanism of nose-to-brain delivery, claims for intranasal delivery and medical devices for epilepsy are discussed.

EXPERT OPINION

Drug-loaded intranasal nanoformulations exhibit different prospective potentials in the management of epilepsy. Considering the foregoing research done in the field of nanotechnology, globally, authors propose nose-to-brain delivery of nanoformulations as a potential technique for the efficient management of epilepsy.

Multifunctional Polymeric Nanoplatforms for Brain Diseases Diagnosis, Therapy and Theranostics

The blood-brain barrier (BBB) acts as a barrier to prevent the central nervous system (CNS) from damage by substances that originate from the blood circulation. The BBB limits drug penetration into the brain and is one of the major clinical obstacles to the treatment of CNS diseases. Nanotechnology-based delivery systems have been tested for overcoming this barrier and releasing related drugs into the brain matrix. In this review, nanoparticles (NPs) from simple to developed delivery systems are discussed for the delivery of a drug to the brain. This review particularly focuses on polymeric nanomaterials that have been used for CNS treatment. Polymeric NPs such as polylactide (PLA), poly (D, L-lactide-co-glycolide) (PLGA), poly (ε-caprolactone) (PCL), poly (alkyl cyanoacrylate) (PACA), human serum albumin (HSA), gelatin, and chitosan are discussed in detail.

Epilepsy Disease and Nose-to-Brain Delivery of Polymeric Nanoparticles: An Overview

Epilepsy is the fourth most common global neurological problem, which can be considered a spectrum disorder because of its various causes, seizure types, its ability to vary in severity and the impact from person to person, as well as its range of co-existing conditions. The approaches to drug therapy of epilepsy are directed at the control of symptoms by chronic administration of antiepileptic drugs (AEDs). These AEDs are administered orally or intravenously but alternative routes of administration are needed to overcome some important limits. Intranasal (IN) administration represents an attractive route because it is possible to reach the brain bypassing the blood brain barrier while the drug avoids first-pass metabolism. It is possible to obtain an increase in patient compliance for the easy and non-invasive route of administration. This route, however, has some drawbacks such as mucociliary clearance and the small volume that can be administered, in fact, only drugs that are efficacious at low doses can be considered. The drug also needs excellent aqueous solubility or must be able to be formulated using solubilizing agents. The use of nanomedicine formulations able to encapsulate active molecules represents a good strategy to overcome several limitations of this route and of conventional drugs. The aim of this review is to discuss the innovative application of nanomedicine for epilepsy treatment using nose-to-brain delivery with particular attention focused on polymeric nanoparticles to load drugs.

Dispersible hydrolytically sensitive nanoparticles for nasal delivery of thyrotropin releasing hormone (TRH)

Nose-to-brain delivery of drugs is affected by nanoparticles (NPs) deposited on the olfactory surface and absorbed directly into the brain. Thyrotropin releasing hormone (TRH), a water soluble drug used for treating suicidal patients, was incorporated into a fast degrading poly(sebacic anhydride) (PSA) NPs. NPs were prepared by a solvent-antisolvent process under strict anhydrous environment to obtain high TRH loading and to avoid premature PSA degradation and TRH release. PSA and TRH were dissolved in a mixture of dichloromethane and ethanol and added dropwise to a dispersion of mannitol particles in heptane as an antisolvent. Mannitol powder was included in the antisolvent, so that formed NPs adhered to the mannitol microparticles for easy isolation and immediate dispersion in water prior to use. The size, surface charge, and morphology of the TRH-PSA NPs were determined using dynamic light scattering (DLS), zeta-potential, and Scanning Electron Microscopy (SEM), respectively. The NPs prepared were uniform and spherical of ~250 nm. Further, the in vitro release profile of TRH from NPs lasted for 12 h with most TRH released within the first hour in water. Concentration dependent cell toxicity studies revealed low toxicity level at low concentrations of the NPs. Surface adsorption of the NPs was also uniform on the cell surface as examined through the odyssey near infrared fluorescence (NIR) images using Indocyanine green (ICG). The NPs are designed to enable direct delivery to the olfactory epithelium using a refillable nasal atomizer that deposits mist onto the olfactory neuro-epithelium.

Intranasal application of PACAP and β-cyclodextrin before the "critical period of proestrous stage" can block ovulation

INTRODUCTION

It was previously shown that intracerebroventricular administration of pituitary adenylate cyclase-activating polypeptide (PACAP) prior to GnRH mobilization in proestrus prevents ovulation in rats. In this study, we examined whether PACAP given intranasally could influence luteinizing hormone (LH) and prolactin (PRL) surges and ovulation.

METHODS

On the day of proestrus PACAP, p-cyclodextrin (modifier of blood-brain barrier) or PACAP + p-cyclodextrin was applied intranasally between 12:30 and 13:00. Blood samples were taken at 16:00, 18:00, and 20:00 for measuring plasma hormone levels. In the next morning, the expelled ova were counted. p-Cyclodextrin was also administered to male and diestrous female rats between 12:30 and 13:00 and blood was taken at 18:00.

RESULTS

PACAP prevented LH and PRL surges and ovulation in about half of the rats, p-cyclodextrin alone more effectively prevented ovulation. When PACAP and p-cyclodextrin were administered together, more rats ovulated like when PACAP given alone. p-Cyclodextrin did not influence LH and PRL levels in diestrous females; however, in males, it significantly enhanced PRL level.

DISCUSSION

Not only the intracerebroventricular, but the intranasal application of PACAP prevented ovulation. p-Cyclodextrin alone is more effective than PACAP and enhances PRL levels in male rats. PACAP and p-cyclodextrin given together weaken each other's effect. p-Cyclodextrin, as excipient of various drugs, has to be used carefully in human medications.

TRH Analog, Taltirelin Protects Dopaminergic Neurons From Neurotoxicity of MPTP and Rotenone

Dopaminergic neurons loss is one of the main pathological characters of Parkinson’s disease (PD), while no suitable neuroprotective agents have been in clinical use. Thyrotropin-releasing hormone (TRH) and its analogs protect neurons from ischemia and various cytotoxins, but whether the effect also applies in PD models remain unclear. Here, we showed that Taltirelin, a long-acting TRH analog, exhibited the neuroprotective effect in both cellular and animal models of PD. The in vitro study demonstrated that Taltirelin (5 μM) reduced the generation of reactive oxygen species (ROS) induced by MPP+ or rotenone, alleviated apoptosis and rescued the viability of SH-SY5Y cells and rat primary midbrain neurons. Interestingly, SH-SY5Y cells treated with Taltirelin also displayed lower level of p-tau (S396) and asparagine endopeptidase (AEP) cleavage products, tau N368 and α-synuclein N103 fragments, accompanied by a lower intracellular monoamine oxidase-B (MAO-B) activity. In the subacute MPTP-induced and chronic rotenone-induced PD mice models, we found Taltirelin (1 mg/kg) significantly improved the locomotor function and preserved dopaminergic neurons in the substantia nigra (SN). In accordance with the in vitro study, Taltirelin down-regulated the levels of p-tau (S396), p-α-synuclein (S129) tau N368 and α-synuclein N103 fragments in SN and striatum. Together, this study demonstrates that Taltirelin may exert neuroprotective effect via inhibiting MAO-B and reducing the oxidative stress and apoptosis, preventing AEP activation and its subsequent pathological cleavage of tau and α-synuclein, thus provides evidence for Taltirelin in protective treatment of PD.

Intravenous and Intratracheal Thyrotropin Releasing Hormone and Its Analog Taltirelin Reverse Opioid-Induced Respiratory Depression in Isoflurane Anesthetized Rats

Thyrotropin releasing hormone (TRH) is a tripeptide hormone and a neurotransmitter widely expressed in the central nervous system that regulates thyroid function and maintains physiologic homeostasis. Following injection in rodents, TRH has multiple effects including increased blood pressure and breathing. We tested the hypothesis that TRH and its long-acting analog, taltirelin, will reverse morphine-induced respiratory depression in anesthetized rats following intravenous or intratracheal (IT) administration. TRH (1 mg/kg plus 5 mg/kg/h, i.v.) and talitrelin (1 mg/kg, i.v.), when administered to rats pretreated with morphine (5 mg/kg, i.v.), increased ventilation from 50% ± 6% to 131% ± 7% and 45% ± 6% to 168% ± 13%, respectively (percent baseline; n = 4 ± S.E.M.), primarily through increased breathing rates (from 76% ± 9% to 260% ± 14% and 66% ± 8% to 318% ± 37%, respectively). By arterial blood gas analysis, morphine caused a hypoxemic respiratory acidosis with decreased oxygen and increased carbon dioxide pressures. TRH decreased morphine effects on arterial carbon dioxide pressure, but failed to impact oxygenation; taltirelin reversed morphine effects on both arterial carbon dioxide and oxygen. Both TRH and talirelin increased mean arterial blood pressure in morphine-treated rats (from 68% ± 5% to 126% ± 12% and 64% ± 7% to 116% ± 8%, respectively; n = 3 to 4). TRH, when initiated prior to morphine (15 mg/kg, i.v.), prevented morphine-induced changes in ventilation; and TRH (2 mg/kg, i.v.) rescued all four rats treated with a lethal dose of morphine (5 mg/kg/min, until apnea). Similar to intravenous administration, both TRH (5 mg/kg, IT) and taltirelin (2 mg/kg, IT) reversed morphine effects on ventilation. TRH or taltirelin may have clinical utility as an intravenous or inhaled agent to antagonize opioid-induced cardiorespiratory depression.

Surface-Modified Nanocarriers for Nose-to-Brain Delivery: From Bioadhesion to Targeting

In the field of nasal drug delivery, nose-to-brain delivery is among the most fascinating applications, directly targeting the central nervous system, bypassing the blood brain barrier. Its benefits include dose lowering and direct brain distribution of potent drugs, ultimately reducing systemic side effects. Recently, nasal administration of insulin showed promising results in clinical trials for the treatment of Alzheimer’s disease. Nanomedicines could further contribute to making nose-to-brain delivery a reality. While not disregarding the need for devices enabling a formulation deposition in the nose’s upper part, surface modification of nanomedicines appears the key strategy to optimize drug delivery from the nasal cavity to the brain. In this review, nanomedicine delivery based on particle engineering exploiting surface electrostatic charges, mucoadhesive polymers, or chemical moieties targeting the nasal epithelium will be discussed and critically evaluated in relation to nose-to-brain delivery.

Nose-to-brain peptide delivery - The potential of nanotechnology

Nose-to-brain (N-to-B) delivery offers to protein and peptide drugs the possibility to reach the brain in a non-invasive way. This article is a comprehensive review of the state-of-the-art of this emerging peptide delivery route, as well as of the challenges associated to it. Emphasis is given on the potential of nanosized drug delivery carriers to enhance the direct N-to-B transport of protein or peptide drugs. In particular, polymer- and lipid- based nanocarriers are comparatively analyzed in terms of the influence of their physicochemical characteristics and composition on their in vivo fate and efficacy. The use of biorecognitive ligands and permeation enhancers in order to enhance their brain targeting efficiency is also discussed. The article concludes highlighting the early stage of this research field and its still unveiled potential. The final message is that more explicatory PK/PD studies are required in order to achieve the translation from preclinical to the clinical development phase.

Intranasal delivery of N-terminal modified leptin-pluronic conjugate for treatment of obesity

Leptin is an adipocyte-secreted hormone that is delivered via a specific transport system across the blood-brain barrier (BBB) to the brain where it acts on the hypothalamus receptors to control appetite and thermogenesis. Peripheral resistance to leptin due to its impaired brain delivery prevents therapeutic use of leptin in overweight and moderately obese patients. To address this problem, we modified the N-terminal amine of leptin with Pluronic P85 (LepNP85) and administered this conjugate intranasally using the nose-to-brain (INB) route to bypass the BBB. We compared this conjugate with the native leptin, the N-terminal leptin conjugate with poly(ethylene glycol) (LepNPEG5K), and two conjugates of leptin with Pluronic P85 attached randomly to the lysine amino groups of the hormone. Compared to the random conjugates of leptin with P85, LepNP85 has shown higher affinity upon binding with the leptin receptor, and similarly to native hormone activated hypothalamus receptors after direct injection into brain. After INB delivery, LepNP85 conjugate was transported to the brain and accumulated in the hypothalamus and hippocampus to a greater extent than the native leptin and LepNPEG5K and activated leptin receptors in hypothalamus at lower dose than native leptin. Our work suggests that LepNP85 can access the brain directly after INB delivery and confirms our hypothesis that the improvement in brain accumulation of this conjugate is due to its enhanced brain absorption. In conclusion, the LepNP85 with optimized conjugation chemistry is a promising candidate for treatment of obesity.

Systems-level thinking for nanoparticle-mediated therapeutic delivery to neurological diseases

Neurological diseases account for 13% of the global burden of disease. As a result, treating these diseases costs $750 billion a year. Nanotechnology, which consists of small (~1-100 nm) but highly tailorable platforms, can provide significant opportunities for improving therapeutic delivery to the brain. Nanoparticles can increase drug solubility, overcome the blood-brain and brain penetration barriers, and provide timed release of a drug at a site of interest. Many researchers have successfully used nanotechnology to overcome individual barriers to therapeutic delivery to the brain, yet no platform has translated into a standard of care for any neurological disease. The challenge in translating nanotechnology platforms into clinical use for patients with neurological disease necessitates a new approach to: (1) collect information from the fields associated with understanding and treating brain diseases and (2) apply that information using scalable technologies in a clinically-relevant way. This approach requires systems-level thinking to integrate an understanding of biological barriers to therapeutic intervention in the brain with the engineering of nanoparticle material properties to overcome those barriers. To demonstrate how a systems perspective can tackle the challenge of treating neurological diseases using nanotechnology, this review will first present physiological barriers to drug delivery in the brain and common neurological disease hallmarks that influence these barriers. We will then analyze the design of nanotechnology platforms in preclinical in vivo efficacy studies for treatment of neurological disease, and map concepts for the interaction of nanoparticle physicochemical properties and pathophysiological hallmarks in the brain. WIREs Nanomed Nanobiotechnol 2017, 9:e1422. doi: 10.1002/wnan.1422 For further resources related to this article, please visit the WIREs website.

A review of intranasal formulations for the treatment of seizure emergencies

Epileptic seizure emergencies are life-threatening conditions, which in their most severe form, status epilepticus, have a high mortality rate if not quickly terminated. Treatment requires rapid delivery of anti-epileptics such as benzodiazepines to the brain. The nasal route is attractive due to its non-invasiveness, potential for direct nose to brain delivery, high vascularity, relatively large absorptive surface area, and avoidance of intestinal/liver metabolism. However, the limited volume of the nasal cavity and poor water solubility of anti-epileptics restrict absorption, leading to insufficient therapeutic brain levels. This review covers various formulation approaches adopted to improve nasal delivery of drugs, especially benzodiazepines, used to treat seizure emergencies. Other general topics such as nasal anatomy, challenges to nasal delivery, and drug/formulation considerations for nose to brain delivery are also discussed.

Phenytoin carried by silica core iron oxide nanoparticles reduces the expression of pharmacoresistant seizures in rats

Aim: The present study was focused to evaluate the anticonvulsant effects of phenytoin (PHT) loaded in the silica core of iron oxide nanoparticles (NPs) in an animal model with pharmacoresistant seizures. Materials & methods: PHT-loaded NPs were synthesized and characterized. The anticonvulsant effects of PHT-loaded NPs were investigated in rats with pharmacoresistant seizures associated with brain P-glycoprotein (P-gp) overexpression. Results & conclusion: In P-gp-overexpressing rats, administration of PHT-loaded NPs resulted in reduced prevalence of clonus (40% p < 0.05) and tonic–clonic seizures (20%; p < 0.02). These effects were not evident when animals were treated with PHT not loaded in the NPs. The results obtained support the notion that NPs can be used as drugs carriers to the brain with pharmacoresistant seizures.

Recent advances in topical delivery of proteins and peptides mediated by soft matter nanocarriers

Proteins and peptides are increasingly important therapeutics for the treatment of severe and complex diseases like cancer or autoimmune diseases due to their high specificity and potency. Their unique structure and labile physicochemical properties, however, require special attention in the production and formulation process as well as during administration. Aside from conventional systemic injections, the topical application of proteins and peptides is an appealing alternative due to its non-invasive nature and thus high acceptance by patients. For this approach, soft matter nanocarriers are interesting delivery systems which offer beneficial properties such as high biocompatibility, easiness of modifications, as well as targeted drug delivery and release. This review aims to highlight and discuss technological developments in the field of soft matter nanocarriers for the delivery of proteins and peptides via the skin, the eye, the nose, and the lung, and to provide insights in advantages, limitations, and practicability of recent advances.

Enhanced brain delivery of lamotrigine with Pluronic(®) P123-based nanocarrier

BACKGROUND

P-glycoprotein (P-gp) mediated drug efflux across the blood-brain barrier (BBB) is an important mechanism underlying poor brain penetration of certain antiepileptic drugs (AEDs). Nanomaterials, as drug carriers, can overcome P-gp activity and improve the targeted delivery of AEDs. However, their applications in the delivery of AEDs have not been adequately investigated. The objective of this study was to develop a nano-scale delivery system to improve the solubility and brain penetration of the antiepileptic drug lamotrigine (LTG).

METHODS

LTG-loaded Pluronic(®) P123 (P123) polymeric micelles (P123/LTG) were prepared by thin-film hydration, and brain penetration capability of the nanocarrier was evaluated.

RESULTS

The mean encapsulating efficiency for the optimized formulation was 98.07%; drug-loading was 5.63%, and particle size was 18.73 nm. The solubility of LTG in P123/LTG can increase to 2.17 mg/mL, making it available as a solution. The in vitro release of LTG from P123LTG presented a sustained-release property. Compared with free LTG, the LTG-incorporated micelles accumulated more in the brain at 0.5, 1, and 4 hours after intravenous administration in rats. Pretreatment with systemic verapamil increased the rapid brain penetration of free LTG but not P123/LTG. Incorporating another P-gp substrate (Rhodamine 123) into P123 micelles also showed higher efficiency in penetrating the BBB in vitro and in vivo.

CONCLUSION

These results indicated that P123 micelles have the potential to overcome the activity of P-gp expressed on the BBB and therefore show potential for the targeted delivery of AEDs. Future studies are necessary to further evaluate the appropriateness of the nanocarrier to enhance the efficacy of AEDs.

Persistent nociception induces anxiety-like behavior in rodents: role of endogenous neuropeptide S

Anxiety disorder is a comorbid condition of chronic pain. Analgesics and anxiolytics, subject to addiction and abuse, are currently used to manage pain and anxiety symptoms. However, the cellular mechanism underlying chronic pain and anxiety interaction remains to be elucidated. We report that persistent nociception following peripheral nerve injury induced anxiety-like behavior in rodents. Brain expression and release of neuropeptide S (NPS), a proposed endogenous anxiolytic peptide, was diminished in rodents with coexisting nociceptive and anxiety-like behaviors. Intracerebroventricular administration of exogenous NPS concurrently improved both nociceptive and anxiety-like behaviors. At the cellular level, NPS enhanced intra-amygdaloidal inhibitory transmission by increasing presynaptic gamma-aminobutyric acid (GABA) release from interneurons. These findings indicate that the interaction between nociceptive and anxiety-like behaviors in rodents may be regulated by the altered NPS-mediated intra-amygdaloidal GABAergic inhibition. The data suggest that enhancing the brain NPS function may be a new strategy to manage comorbid pain and anxiety.

Neuropeptides as targets for the development of anticonvulsant drugs

Epilepsy is a common neurological disorder characterized by recurrent seizures. These seizures are due to abnormal excessive and synchronous neuronal activity in the brain caused by a disruption of the delicate balance between excitation and inhibition. Neuropeptides can contribute to such misbalance by modulating the effect of classical excitatory and inhibitory neurotransmitters. In this review, we discuss 21 different neuropeptides that have been linked to seizure disorders. These neuropeptides show an aberrant expression and/or release in animal seizure models and/or epilepsy patients. Many of these endogenous peptides, like adrenocorticotropic hormone, angiotensin, cholecystokinin, cortistatin, dynorphin, galanin, ghrelin, neuropeptide Y, neurotensin, somatostatin, and thyrotropin-releasing hormone, are able to suppress seizures in the brain. Other neuropeptides, such as arginine-vasopressine peptide, corticotropin-releasing hormone, enkephalin, β-endorphin, pituitary adenylate cyclase-activating polypeptide, and tachykinins have proconvulsive properties. For oxytocin and melanin-concentrating hormone both pro- and anticonvulsive effects have been reported, and this seems to be dose or time dependent. All these neuropeptides and their receptors are interesting targets for the development of new antiepileptic drugs. Other neuropeptides such as nesfatin-1 and vasoactive intestinal peptide have been less studied in this field; however, as nesfatin-1 levels change over the course of epilepsy, this can be considered as an interesting marker to diagnose patients who have suffered a recent epileptic seizure.

Strategies to deliver peptide drugs to the brain

Neurological diseases such as neurodegeneration, pain, psychiatric disorders, stroke, and brain cancers would greatly benefit from the use of highly potent and specific peptide pharmaceuticals. Peptides are especially desirable because of their low inherent toxicity. The presence of the blood brain barrier (BBB), their short duration of action, and their need for parenteral administration limits their clinical use. However, over the past decade there have been significant advances in delivering peptides to the central nervous system. Angiopep peptides developed by Angiochem (Montreal, Canada), transferrin antibodies developed by ArmaGen (Santa Monica, USA), and cell penetrating peptides have all shown promise in delivering therapeutic peptides across the BBB after intravenous administration. Noninvasive methods of delivering peptides to the brain include the use of chitosan amphiphile nanoparticles for oral delivery and nose to brain strategies. The uptake of the chitosan amphiphile nanoparticles by the gastrointestinal epithelium is important for oral peptide delivery. Finally protecting peptides from plasma degradation is integral to the success of most of these peptide delivery strategies.

What future for neuroendocrinology in psychiatry?

In psychiatry, neuroendocrine techniques were initially considered a potential "window into the brain" by indirectly marking central nervous system limbic dysfunction. At present this conception has evolved, owing to significant progress over the last decades demonstrating direct involvement of neuropeptides and neurohormones in psychiatric diseases. In a synchronic perspective, neuroendocrine investigations evaluate a functional status at a given moment in the evolution of the disease, which results from both etiopathogenic processes and compensatory homeostatic mechanisms. These vital physiological changes appear to be potential targets for novel hormonally based pharmacotherapies. However, in the past few years, the interest for the study of neuroendocrine dysregulations in psychiatric patients has declined. In order to better understand this relative disinterest, this article will attempt to shed light on strengths and limitations of the neuroendocrine approaches in psychiatry. It is necessary to bear in mind that the usefulness of these techniques in the clinical, pathophysiological and therapeutic fields depends largely on the selectivity of stimuli and the appropriateness of the methodologies used. Owing to the complexity of the clinical phenomena, multifactorial approaches (combining several neuroendocrine challenge tests to imaging, immunological, neurophysiological, neurochemical and/or genetic techniques) are to be privileged in psychiatric investigations. Despite the inherent limitations of these approaches, due to their technical and ethical constraints, the neuroendocrine strategy can inform modern clinical practice and lead to new breakthroughs in future science and practice.

Polymeric nanoparticles to control the differentiation of neural stem cells in the subventricular zone of the brain

Herein, we report the use of retinoic acid-loaded polymeric nanoparticles as a potent tool to induce the neuronal differentiation of subventricular zone neural stem cells. The intracellular delivery of retinoic acid by the nanoparticles activated nuclear retinoic acid receptors, decreased stemness, and increased proneurogenic gene expression. Importantly, this work reports for the first time a nanoparticle formulation able to modulate in vivo the subventricular zone neurogenic niche. The work further compares the dynamics of initial stages of differentiation between SVZ cells treated with retinoic acid-loaded polymeric nanoparticles and solubilized retinoic acid. The nanoparticle formulation developed here may ultimately offer new perspectives to treat neurodegenerative diseases.

Drug development of intranasally delivered peptides

Intranasal drug delivery has attracted increasing attention as a noninvasive route of administration for therapeutic proteins and peptides. The delivery of therapeutic peptides through the nasal route provides an alternative to intravenous or subcutaneous injections. This review highlights the drug-development considerations unique to nasal therapeutics and discusses some of the factors and strategies that affect and can improve nasal absorption of peptides. The selectivity and good safety profile typical of peptide therapeutics, along with the dose limitation for intranasal administration, can provide challenges in drug development. Therefore, nasal peptide therapeutics often require special considerations in the nonclinical safety evaluations, such as determining drug exposure in the context of the maximum feasible dose in order to adequately prepare nasal products for clinical studies.

Intranasal application of secretin, similarly to intracerebroventricular administration, influences the motor behavior of mice probably through specific receptors

Secretin and its receptors show wide distribution in the central nervous system. It was demonstrated previously that intravenous (i.v.) and intracerebroventricular (i.c.v.) application of secretin influenced the behavior of rat, mouse, and human. In our previous experiment, we used a special animal model, Japanese waltzing mice (JWM). These animals run around without stopping (the ambulation distance is very limited) and they do not bother with their environment. The i.c.v. secretin attenuated this hyperactive repetitive movement. In the present work, the effect of i.c.v. and intranasal (i.n.) application of secretin was compared. We have also looked for the presence of secretin receptors in the brain structures related to motor functions. Two micrograms of i.c.v. secretin improved the horizontal movement of JWM, enhancing the ambulation distance. It was nearly threefold higher in treated than in control animals. The i.n. application of secretin to the left nostril once or twice a day or once for 3 days more effectively enhanced the ambulation distance than i.c.v. administration. When secretin was given twice a day for 3 days it had no effect. Secretin did not improve the explorative behavior (the rearing), of JWM. With the use of in situ hybridization, we have found very dense secretin receptor labeling in the cerebellum. In the primary motor cortex and in the striatum, only a few labeled cells were seen. It was supposed that secretin exerted its effect through specific receptors, mainly present in the cerebellum.

Novel thyrotropin-releasing hormone analogs: a patent review

INTRODUCTION

The potential therapeutic applications of thyrotropin-releasing hormone (TRH) have attracted attention, based on its broad-spectrum neuropharmacological action rather than its endocrine properties. These central nervous system (CNS)-mediated effects provide the rationale for use of TRH and its analogs in the treatment of brain and spinal injury, and CNS disorders like schizophrenia, Alzheimer's disease, epilepsy, amyotrophic lateral sclerosis, Parkinson's disease, depression, shock and ischemia.

AREAS COVERED

This review summarizes the patent literature and advances in the discovery and development of novel TRH analogs over the past 20 years. It provides a comprehensive overview of the development of new TRH analogs, giving emphasis to their pharmaceutical profile.

EXPERT OPINION

The use of TRH in the treatment of various CNS disorders has been proven clinically. However, TRH itself is a poor drug candidate due to its short plasma half-life (5 min), poor biopharmaceutical properties (low intestinal and CNS permeability) and endocrine side effect. Nevertheless, researchers have come up with metabolically stable, more potent and selective TRH analogs and prodrugs. Taltirelin, one of the TRH analogs, has been approved under the trade name of Ceredist(®) in Japan for the treatment of spinocerebellar degeneration. Several other TRH analogs are in various stages of preclinical or clinical development.

Intranasal delivery of neuropeptides

A major barrier to entry of neuropeptides into the brain is low bioavailability and presence of the blood-brain barrier. Intranasal delivery of neuropeptides provides a potentially promising alternative to other routes of administration, since a direct pathway exists between the olfactory neuroepithelium and the brain. Use of the rat as an animal model in nose to brain delivery of neuropeptides allows for several advantages, including a large surface area within the nasal cavity dedicated to olfactory epithelium and robust neuronal pathways extending to and from most areas of the brain from the nose via the olfactory cortex. A major disadvantage to using rats for nose to brain delivery is the difficulty in selectively targeting the posterior olfactory epithelium (which facilitates delivery to the brain) over the more anterior respiratory epithelium (which facilitates delivery to the lungs and secondarily to the peripheral blood) in the nasal cavity. We have developed a novel delivery system that consists of surgically implanting stainless-steel cannulas in the dorsal aspect of the nasal cavity overlying the olfactory neuroepithelium, thereby allowing neuropeptide compounds to bypass the respiratory epithelium.

Thyrotropin-releasing hormone d,l polylactide nanoparticles (TRH-NPs) protect against glutamate toxicity in vitro and kindling development in vivo

Thyrotropin-releasing hormone (TRH) is reported to have anticonvulsant effects in animal seizure models and certain intractable epileptic patients. However, its duration of action is limited by rapid tissue metabolism and the blood brain barrier. Direct nose-brain delivery of neuropeptides in sustained-release biodegradable nanoparticles (NPs) is a promising mode of therapy for enhancing CNS bioavailability. Bioactivity/neuroprotection of d,l polylactide nanoparticles containing TRH was assessed against glutamate toxicity in cultured rat fetal hippocampal neurons. Subsequently, we utilized the kindling model of temporal lobe epilepsy to determine if intranasal administration of nanoparticles containing TRH (TRH-NPs) could inhibit kindling development. Animals received daily treatments of either blank (control) or TRH-NPs for 7 days before initiation of kindling. On day 8 and each day thereafter until either fully kindled or until day 20, the animals received daily treatments before receiving a kindling stimulus 3 h later. Afterdischarge duration (ADD) was assessed via electroencephalographs recorded from electrodes in the basolateral amygdalae and behavioral seizure stereotypy was simultaneously recorded digitally. Intranasal application of TRH-NPs resulted in a significant reduction in seizure ADD as kindling progressed, while the number of stimulations required to reach stage V seizures and to become permanently kindled was significantly greater in TRH-NP-treated subjects. Additionally, delay to clonus was significantly prolonged while clonus duration was reduced indicating a less severe seizure in TRH-NP-treated subjects. Our results provide proof of principle that intranasal delivery of sustained-release TRH-NPs may be neuroprotective and can be utilized to suppress seizures and perhaps epileptogenesis.

Intranasal delivery of antiepileptic medications for treatment of seizures

Acute isolated seizure, repetitive or recurrent seizures, and status epilepticus are all deemed medical emergencies. Mortality and worse neurologic outcome are directly associated with the duration of seizure activity. A number of recent reviews have described consensus statements regarding the pharmacologic treatment protocols for seizures when patients are in pre-hospital, institutional, and home-bound settings. Benzodiazepines, such as lorazepam, diazepam, midazolam, and clonazepam are considered to be medications of first choice. The rapidity by which a medication can be delivered to the systemic circulation and then to the brain plays a significant role in reducing the time needed to treat seizures and reduce opportunity for damage to the CNS. Speed of delivery, particularly outside of the hospital, is enhanced when transmucosal routes of delivery are used in place of an intravenous injection. Intranasal transmucosal delivery of benzodiazepines is useful in reducing time to drug administration and cessation of seizures in the pre-hospital setting, when actively seizing patients arrive in the emergency room, and at home where caregivers treat their dependents. This review summarizes factors to consider when choosing a benzodiazepine for intranasal administration, including formulation and device considerations, pharmacology and pharmacokinetic/pharmacodynamic profiles. A review of the most relevant clinical studies in epilepsy patients will provide context for the relative success of this technique with a number of benzodiazepines and relatively less sophisticated nasal preparations. Neuropeptides delivered intranasally, crossing the blood-brain barrier via the olfactory system, may increase the availability of medications for treatment of epilepsy. Consequently, there remains a significant unmet medical need to serve the pharamcotherapeutic requirements of epilepsy patients through commercial development and marketing of intranasal antiepileptic products.