Food consumption and activity levels increase in rats following intranasal Hypocretin-1.

Hypocretin-1 (HC, orexin-A) is a neuropeptide involved in regulating physiological functions of sleep, appetite and arousal, and it has been shown that intranasal (IN) administration can target HC to the brain. Recent clinical studies have shown that IN HC has functional effects in human clinical trials. In this study, we use rats to determine whether IN HC has an immediate effect on food consumption and locomotor activity, whether distribution in the brain after IN delivery is dose-dependent, and whether MAPK and PDK1 are affected after IN delivery. Food intake and wheel-running activity were quantified for 24h after IN delivery. Biodistribution was determined 30min after IN delivery of both a high and low dose of 125I-radiolabelled HC throughout the brain and other bodily tissues, while Western blots were used to quantify changes in cell signaling pathways (MAPK and PDK1) in the brain. Intranasal HC significantly increased food intake and wheel activity within 4h after delivery, but balanced out over the course of 24h. The distribution studies showed dose-dependent delivery in the CNS and peripheral tissues, while PDK1 was significantly increased in the brain 30min after IN delivery of HC. This study adds to the growing body of evidence that IN administration of HC is a promising strategy for treatment of HC related behaviors.

Intranasal delivery of growth differentiation factor 5 to the central nervous system.

CONTEXT: Growth differentiation factor 5 (GDF5), in addition to its role in bone and joint development, protects dopaminergic (DA) neurons from degeneration, and is a potential therapeutic agent for Parkinson's disease. Its large size and insolubility at physiologic pH are obstacles for drug administration to the central nervous system (CNS) in humans. OBJECTIVE: In this study, formulations to deliver GDF5 to the brain using intranasal (IN) administration were developed. MATERIALS AND METHODS: IN administration of GDF5 in acidic buffer, 20 mM sodium acetate (NaAc) at pH 4.25, was performed in rats. Also, a lipid microemulsion (LME) comprised of olive oil and phosphatidylserine (PS) was used to formulate GDF5 at neutral pH for IN administration. Tissue concentrations of GDF5 were determined by both gamma counting and enzyme-linked immunosorbent assay (ELISA). RESULTS: IN administration of GDF5 in acidic buffers bypassed the blood-brain barrier (BBB), resulting in delivery to the brain with limited systemic exposure. IN administration of GDF5-LME increased drug targeting to the midbrain eightfold when compared to IN administration of GDF5 in acidic buffer. DISCUSSION AND CONCLUSION: This study is the first to show that GDF5 can be formulated at neutral pH and can be directly delivered to the CNS via IN administration, with biologically relevant concentrations in the midbrain where it may be used to treat Parkinson's disease.

Intranasal delivery of deferoxamine reduces spatial memory loss in APP/PS1 mice.

Intranasal administration, which bypasses the blood-brain barrier and minimizes systemic exposure, is a non-invasive alternative for targeted drug delivery to the brain. While identification of metal dysregulation in Alzheimer's brain has led to the development of therapeutic metal-binding agents, targeting to the brain has remained an issue. The purpose of this study was to both determine concentrations of deferoxamine (DFO), a high-affinity iron chelator, reaching the brains of mice after intranasal administration and to determine its efficacy in a mouse model of spatial memory loss. Intranasal administration of DFO (2.4 mg) labeled with (59)Fe (75 µCi) to C57 mice resulted in micromolar concentrations at 30 min within brain parenchyma. After 3 months of intranasal DFO treatment, 2.4 mg three times per week, 48-week-old APP/PS1 mice had significantly reduced escape latencies in Morris water maze compared to vehicle-treated mice. This is the first report that intranasal DFO improves spatial memory in a mouse model of Alzheimer's disease and demonstrates that intranasal DFO reaches the brain in therapeutic doses.

Intranasal phosphoramidon increases beta-amyloid levels in wild-type and NEP/NEP2-deficient mice.

Intranasal administration is emerging as a reliable and non-invasive method to bypass the blood-brain barrier and deliver drugs to the brain. This approach has been primarily used to explore therapeutic avenues for neurological diseases. However, intranasal administration could also be used to create animal models of brain disease. Beta-amyloid peptide (Aß) accumulation is a key feature of Alzheimer's disease (AD), and the most common models of AD are transgenic mice expressing mutant human genes linked to familial AD. An alternative model of amyloidosis utilizes intracerebroventricular infusion of thiorphan or phosphoramidon to block the activity of key Aß degrading enzymes (NEP, NEP2) resulting in accumulation of Aß. Here, we demonstrate that intranasal administration of phosphoramidon produces significantly elevated cerebral Aß levels in wild-type mice. Furthermore, intranasal phosphoramidon administration in double knockout mice lacking NEP and NEP2 also showed increased levels of Aß(40). These data show that intranasal delivery of drugs can be used to model AD and suggest that other phosphoramidon-sensitive peptidases are degrading Aß in NEP/NEP2-deficient mice.