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Matiashova L, Hoogkamer AL, Timper K. The Role of the Olfactory System in Obesity and Metabolism in Humans: A Systematic Review and Meta-Analysis. Metabolites 2023; 14:16. [PMID: 38248819 PMCID: PMC10821293 DOI: 10.3390/metabo14010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
Obesity, linked to chronic diseases, poses a global health challenge. While the role of the olfactory system in energy homeostasis is well-documented in rodents, its role in metabolism regulation and obesity in humans remains understudied. This review examines the interplay between olfactory function and metabolic alterations in human obesity and the effects of bariatric surgery on olfactory capabilities in humans. Adhering to PRISMA guidelines, a systematic review and meta-analysis was conducted, focusing exclusively on original human studies. From 51 articles, 14 were selected for the meta-analysis. It was found that variations in olfactory receptor genes influence the susceptibility to odors and predisposition to weight gain and poor eating habits. Bariatric surgery, particularly sleeve gastrectomy, shows significant improvements in olfactory function (SMD 2.37, 95% CI [0.96, 3.77], I = 92%, p = 0.001), especially regarding the olfactory threshold (SMD -1.65, 95% CI [-3.03, -0.27], I = 81%, p = 0.02). There is a bidirectional relationship between olfactory function and metabolism in humans. Bariatric surgery improves olfactory perception in obese patients, but it is still unclear if impacting the olfactory system directly affects eating behavior and the energy balance. However, these findings open novel avenues for future studies addressing the olfactory system as a novel target to alter systemic metabolism in humans.
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Affiliation(s)
- Lolita Matiashova
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
| | - Anouk Lisa Hoogkamer
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
| | - Katharina Timper
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
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AlBilasi TM, Alanazi RM, AlDhawi LF, Albathi AA. Outcome and Safety of Insulin in the Management of Smell Loss: A Systematic Review. EAR, NOSE & THROAT JOURNAL 2023:1455613231201028. [PMID: 37776014 DOI: 10.1177/01455613231201028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023] Open
Abstract
Background: Olfactory dysfunction can negatively impact the quality of life and increase the risk of danger from warning odors. Various factors can cause olfactory dysfunction, including COVID-19 infection, which has increased anosmia cases. No medications are approved; however, recent studies have suggested that intranasal insulin could effectively treat olfactory dysfunction. Aim: To comprehensively evaluate the effectiveness and safety of intranasal insulin in treating olfactory dysfunction. Materials and Methods: PubMed, Google Scholar, and CENTRAL databases were searched using specific keywords, and the outputs were screened using the Rayyan AI system. Original research articles published without time frame limitations that reported the relevant outcomes were included. The reviewers performed the screening and data extraction, and any disagreements were resolved by a third senior author. Results: This systematic review identified 66 references from 3 databases, with 45 articles meeting the criteria for review after duplicates were removed. Six articles met the inclusion criteria and were selected, including 177 subjects. The selected studies consisted of various study designs, including pilot studies, placebo-controlled trials, crossover studies, and randomized clinical trials. The findings showed that intranasal insulin therapy had beneficial effects on olfactory function. Specifically, improvements were observed in olfactory detection and discrimination in patients with post-COVID-19 anosmia, olfactory threshold performance in healthy participants, and odor identification in hyposmic patients. However, there were variations in the observed effects based on different doses of insulin administered and gender differences. It also shows that using insulin provides good outcomes. Using it intranasally was safe and did not cause any complications. Conclusion: Intranasal insulin has shown promising results as a potentially safe treatment for olfactory dysfunction. Studies suggest that it can improve olfactory thresholds. Further studies are needed to investigate optimal doses and potential gender differences in response.
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Affiliation(s)
- Thamer M AlBilasi
- Department of Otolaryngology - Head & Neck Surgery (ORL-H&N), Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia
| | - Rawan Mahmoud Alanazi
- A Medical Student College of Medicine, Dar Al Uloom University, Riyadh, Saudi Arabia
| | - Lama F AlDhawi
- A Medical Student at Al-Maarefa University College of Medicine, Riyadh, Saudi Arabia
| | - Abeer Ali Albathi
- Department of Otolaryngology - Head & Neck Surgery (ORL-H&N), Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia
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Schumann K, Rodriguez-Raecke R, Sijben R, Freiherr J. Elevated Insulin Levels Engage the Salience Network during Multisensory Perception. Neuroendocrinology 2023; 114:90-106. [PMID: 37634508 DOI: 10.1159/000533663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 08/14/2023] [Indexed: 08/29/2023]
Abstract
INTRODUCTION Brain insulin reactivity has been reported in connection with systematic energy metabolism, enhancement in cognition, olfactory sensitivity, and neuroendocrine circuits. High receptor densities exist in regions important for sensory processing. The main aim of the study was to examine whether intranasal insulin would modulate the activity of areas in charge of olfactory-visual integration. METHODS As approach, a placebo-controlled double-blind within crossover design was chosen. The experiments were conducted in a research unit of a university hospital. On separate mornings, twenty-six healthy normal-weight males aged between 19 and 31 years received either 40 IU intranasal insulin or placebo vehicle. Subsequently, they underwent 65 min of functional magnetic resonance imaging whilst performing an odor identification task. Functional brain activations of olfactory, visual, and multisensory integration as well as insulin versus placebo were assessed. Regarding the odor identification task, reaction time, accuracy, pleasantness, and intensity measurements were taken to examine the role of integration and treatment. Blood samples were drawn to control for peripheral hormone concentrations. RESULTS Intranasal insulin administration during olfactory-visual stimulation revealed strong bilateral engagement of frontoinsular cortices, anterior cingulate, prefrontal cortex, mediodorsal thalamus, striatal, and hippocampal regions (p ≤ 0.001 familywise error [FWE] corrected). In addition, the integration contrast showed increased activity in left intraparietal sulcus, left inferior frontal gyrus, left superior frontal gyrus, and left middle frontal gyrus (p ≤ 0.013 FWE corrected). CONCLUSIONS Intranasal insulin application in lean men led to enhanced activation in multisensory olfactory-visual integration sites and salience hubs which indicates stimuli valuation modulation. This effect can serve as a basis for understanding the connection of intracerebral insulin and olfactory-visual processing.
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Affiliation(s)
- Katja Schumann
- Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany
| | - Rea Rodriguez-Raecke
- Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany
- Brain Imaging Facility, Interdisciplinary Center for Clinical Research, RWTH Aachen University, Aachen, Germany
| | - Rik Sijben
- Brain Imaging Facility, Interdisciplinary Center for Clinical Research, RWTH Aachen University, Aachen, Germany
| | - Jessica Freiherr
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander, University Erlangen-Nürnberg, Erlangen, Germany
- Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
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Novel Therapies in Olfactory Disorders. CURRENT OTORHINOLARYNGOLOGY REPORTS 2022; 10:427-432. [PMID: 36312744 PMCID: PMC9589531 DOI: 10.1007/s40136-022-00436-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2022] [Indexed: 11/07/2022]
Abstract
Purpose of Review To summarize and critically review the recent literature on novel treatments for olfactory disorders (OD). Recent Findings Emerging therapies in the management of OD include multiple vitamins and supplements, biologics, neuromodulators, and intranasal agents. There is also an active investigation into treatments that harness the neuroregenerative properties of the olfactory epithelium, such as platelet-rich plasma and stem cell transplantation. Summary Successful management of OD is multimodal and tailored to the underlying etiology. As the findings of further investigations accrue, the management of OD will undoubtedly continue to be advanced and refined, and likely harness the intrinsic neuroregenerative properties of the olfactory system.
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Pieniak M, Oleszkiewicz A, Avaro V, Calegari F, Hummel T. Olfactory training - Thirteen years of research reviewed. Neurosci Biobehav Rev 2022; 141:104853. [PMID: 36064146 DOI: 10.1016/j.neubiorev.2022.104853] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
Abstract
The sense of smell is interrelated with psychosocial functioning. Olfactory disorders often decrease quality of life but treatment options for people with olfactory loss are limited. Additionally, olfactory loss accompanies and precedes psychiatric and neurodegenerative diseases. Regular, systematic exposure to a set of odors, i.e., olfactory training (OT) has been offered for rehabilitation of the sense of smell in clinical practice. As signals from the olfactory bulb are directly projected to the limbic system it has been also debated whether OT might benefit psychological functioning, i.e., mitigate cognitive deterioration or improve emotional processing. In this review we synthesize key findings on OT utility in the clinical practice and highlight the molecular, cellular, and neuroanatomical changes accompanying olfactory recovery in people with smell loss as well as in experimental animal models. We discuss how OT and its modifications have been used in interventions aiming to support cognitive functions and improve well-being. We delineate main methodological challenges in research on OT and suggest areas requiring further scientific attention.
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Affiliation(s)
- Michal Pieniak
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany; University of Wrocław, Faculty of Historical and Pedagogical Sciences, Institute of Psychology, Wroclaw, Poland.
| | - Anna Oleszkiewicz
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany; University of Wrocław, Faculty of Historical and Pedagogical Sciences, Institute of Psychology, Wroclaw, Poland
| | - Vittoria Avaro
- CRTD-Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Federico Calegari
- CRTD-Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Thomas Hummel
- Smell and Taste Clinic, Technische Universitat Dresden, Dresden, Germany
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Bloody olfaction? Confounding associations of sex and age on the influence of blood parameters and body weight on odor identification performance in healthy adults. Physiol Behav 2022; 254:113907. [PMID: 35817126 DOI: 10.1016/j.physbeh.2022.113907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 07/04/2022] [Accepted: 07/07/2022] [Indexed: 11/20/2022]
Abstract
Olfactory function and nutrition are closely related and may influence each other via metabolic parameters. However, the relationship between nutritional blood parameters and olfactory performance is still unclear. Inconclusive findings exist for specific blood parameters. In this extensive analysis, we examined the relationship between olfactory performance, measured with MONEX-40, as well as intensity and pleasantness ratings with 38 metabolic blood parameters, age, sex, and the anthropometric measurements body mass index (BMI) and body fat percentage (BFP). Therefore, we included data of 418 healthy, well-phenotyped Caucasians of the Enable cohort. We replicated age-dependent olfactory identification scores (p < 0.001) and found slight evidence for a body fat dependence measured with BFP (BF10 = 10.466). We further identified a sex difference only in middle-aged adults (p < 0.001) that could be explained by environmental factors. Several blood parameters correlated significantly with the MONEX-40 score (p < 0.05 - p < 0.001). However, these effects diminished after adjusting for sex and age (p > 0.9) that were identified as confounders. The same applies for BFP. In addition, no parameters were identified to correlate significantly with perceived olfactory intensity or pleasantness score if controlled for sex and age (p > 0.08). Our results suggest that metabolic blood parameters are not related to olfactory identification performance in a relevant manner and highlight the importance of controlling for sex and age in chemosensory research.
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Nag AK, Saltagi AK, Saltagi MZ, Wu AW, Higgins TS, Knisely A, Ting JY, Illing EA. Management of Post-Infectious Anosmia and Hyposmia: A Systematic Review. Ann Otol Rhinol Laryngol 2022:34894221118186. [PMID: 35959948 DOI: 10.1177/00034894221118186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Anosmia and hyposmia significantly affect patients' quality of life and have many etiologies, including trauma, inflammatory conditions including chronic rhinosinusitis, neoplasm, and viral infections, such as rhinovirus and SARS-CoV-2. OBJECTIVE Our purpose was to establish whether a consensus exists regarding optimal management of olfactory dysfunction and to provide insight into the treatment of anosmia in the current climate of increased prevalence secondary to COVID-19. Thus, we aimed to systematically review the literature on the management of non-Chronic-rhinosinusitis- related anosmia/hyposmia. METHODS PubMed, EMBASE, and Cochrane databases were searched for articles published since January 1990 using terms combined with Medical Subject Headings (MeSH). We included articles evaluating management of anosmia and hyposmia written in the English language, with original data, a minimum of 3 months of follow-up except for COVID-related studies, at least 2 patients, and well-defined and measurable outcomes. RESULTS A total of 3013 unique titles were returned upon the initial search. Of these, 297 abstracts were examined, yielding 19 full texts meeting inclusion criteria (8 with level 1 evidence, 3 with level 2, 1 with level 3, and 7 with level 4). The studies included a total of 1522 subjects, with follow up ranging from 3 to 72 months, with an exception for COVID related studies. Endpoints were based on clinically significant improvements of olfactory functions as measured through validated smell tests. Treatments with the most robust data were intranasal corticosteroids and olfactory training. CONCLUSION The literature on the treatment of anosmia and hyposmia includes randomized trials showing the efficacy of a few modalities. While further research is needed to expand therapeutic options for this debilitating condition, the current literature supports the use of olfactory training and topical corticosteroids.
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Affiliation(s)
- Amit K Nag
- Department of Otolaryngology-Head and Neck Surgery, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Abdul K Saltagi
- Indiana University School of Medicine, Indianapolis, IN, USA
| | - Mohamad Z Saltagi
- Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, IN, USA
| | - Arthur W Wu
- Cedars-Sinai Division of Otolaryngology, Los Angeles, CA, USA
| | - Thomas S Higgins
- Department of Otolaryngology-Head and Neck Surgery, University of Louisville, Louisville, KY, USA.,Kentuckiana Ear, Nose & Throat, Louisville, KY, USA
| | - Anna Knisely
- Department of Otolaryngology, Head and Neck Surgery, Swedish Medical Center, Seattle, WA, USA
| | - Jonathan Y Ting
- Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, IN, USA
| | - Elisa A Illing
- Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, IN, USA
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Sivakumar R, White J, Villwock J. Olfactory dysfunction in type II diabetes: Therapeutic options and lessons learned from other etiologies - A scoping review. Prim Care Diabetes 2022; 16:543-548. [PMID: 35659730 PMCID: PMC10184301 DOI: 10.1016/j.pcd.2022.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/21/2022] [Accepted: 05/21/2022] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Olfactory dysfunction (OD) is highly prevalent amongst type 2 diabetes mellitus (DM2) patients and has many associated health risks. For example, OD can lead to poor nutrition, safety issues related to diminished hazard detection, and increased mortality rates. While limited research exists about therapeutics for DM2-associated OD, recovery of olfactory function is better studied in other pathologic states. The objectives of this scoping review are to synthesize the existing data on interventions for DM2-associated OD and present the evidence for therapies that have been utilized for non-DM2-associated causes of OD. Additionally, the potential therapeutic opportunities for patients with DM2 are explored. METHODS A scoping review was conducted with a medical librarian to identify studies investigating treatments of DM2-related OD. 6 databases were searched (Embase, CINAHL, the Cochrane Library, Google Scholar, OVID Medline, and Web of Science). Studies were eligible if the primary discussion involved treatment of olfactory deficits in the context of DM2. All publication dates were included, and studies published in languages other than English were excluded. RESULTS 3631 articles were identified; 3 articles met inclusion criteria and underwent full text review. Hyperbaric oxygen (HBO), the DPP-4 inhibitor Linagliptin and the GLP-1 agonists Exenatide and Liraglutide are the only therapeutics that have been used in the context of DM2. Only HBO and GLP-1 agonists produced statistically significant improvements in olfactory identification. The literature regarding non-DM2-associated OD supports interventions such as olfactory training, dietary supplements, and intranasal insulin. Specifically, olfactory training was very effective in many contexts such as post-viral and traumatic OD while being affordable and non-invasive. CONCLUSION This scoping review of olfactory rehabilitation options for DM2-induced OD demonstrates a paucity of prospective investigations of plausible therapeutics. Additionally, treatments for OD related to non-DM2-associated etiologies, such as olfactory training, are well-studied, efficacious, and should be investigated in the context of DM2. Future investigation has the potential to enhance the quality of clinical intervention for OD and improve short- and long-term outcomes for DM2 patients.
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Affiliation(s)
- Ram Sivakumar
- University of Kansas Medical Center, Department of Otolaryngology, 3901 Rainbow Boulevard Mailstop 3010, Kansas City, KS 66160, USA.
| | - Jacob White
- University of Kansas Medical Center, A.R. Dykes Library, 2100 W 39th Ave, Mailstop 1050, Kansas City KS 66103, USA
| | - Jennifer Villwock
- University of Kansas Medical Center, Department of Otolaryngology, 3901 Rainbow Boulevard Mailstop 3010, Kansas City, KS 66160, USA.
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Riech- und Schmeckstörungen. DGNEUROLOGIE 2022. [PMCID: PMC9007254 DOI: 10.1007/s42451-022-00434-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.
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Patel ZM, Holbrook EH, Turner JH, Adappa ND, Albers MW, Altundag A, Appenzeller S, Costanzo RM, Croy I, Davis GE, Dehgani-Mobaraki P, Doty RL, Duffy VB, Goldstein BJ, Gudis DA, Haehner A, Higgins TS, Hopkins C, Huart C, Hummel T, Jitaroon K, Kern RC, Khanwalkar AR, Kobayashi M, Kondo K, Lane AP, Lechner M, Leopold DA, Levy JM, Marmura MJ, Mclelland L, Miwa T, Moberg PJ, Mueller CA, Nigwekar SU, O'Brien EK, Paunescu TG, Pellegrino R, Philpott C, Pinto JM, Reiter ER, Roalf DR, Rowan NR, Schlosser RJ, Schwob J, Seiden AM, Smith TL, Soler ZM, Sowerby L, Tan BK, Thamboo A, Wrobel B, Yan CH. International consensus statement on allergy and rhinology: Olfaction. Int Forum Allergy Rhinol 2022; 12:327-680. [PMID: 35373533 DOI: 10.1002/alr.22929] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/01/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O). METHODS Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus. RESULTS The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies. CONCLUSION This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.
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Affiliation(s)
- Zara M Patel
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Eric H Holbrook
- Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
| | - Justin H Turner
- Otolaryngology, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - Nithin D Adappa
- Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mark W Albers
- Neurology, Harvard Medical School, Boston, Massachusetts, USA
| | - Aytug Altundag
- Otolaryngology, Biruni University School of Medicine, İstanbul, Turkey
| | - Simone Appenzeller
- Rheumatology, School of Medical Sciences, University of Campinas, São Paulo, Brazil
| | - Richard M Costanzo
- Physiology and Biophysics and Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Ilona Croy
- Psychology and Psychosomatic Medicine, TU Dresden, Dresden, Germany
| | - Greg E Davis
- Otolaryngology, Proliance Surgeons, Seattle and Puyallup, Washington, USA
| | - Puya Dehgani-Mobaraki
- Associazione Naso Sano, Umbria Regional Registry of Volunteer Activities, Corciano, Italy
| | - Richard L Doty
- Smell and Taste Center, Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Valerie B Duffy
- Allied Health Sciences, University of Connecticut, Storrs, Connecticut, USA
| | | | - David A Gudis
- Otolaryngology, Columbia University Irving Medical Center, New York, USA
| | - Antje Haehner
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | - Thomas S Higgins
- Otolaryngology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Claire Hopkins
- Otolaryngology, Guy's and St. Thomas' Hospitals, London Bridge Hospital, London, UK
| | - Caroline Huart
- Otorhinolaryngology, Cliniques universitaires Saint-Luc, Institute of Neuroscience, Université catholgique de Louvain, Brussels, Belgium
| | - Thomas Hummel
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | | | - Robert C Kern
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Ashoke R Khanwalkar
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Masayoshi Kobayashi
- Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Mie, Japan
| | - Kenji Kondo
- Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Andrew P Lane
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Matt Lechner
- Otolaryngology, Barts Health and University College London, London, UK
| | - Donald A Leopold
- Otolaryngology, University of Vermont Medical Center, Burlington, Vermont, USA
| | - Joshua M Levy
- Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Michael J Marmura
- Neurology Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Lisha Mclelland
- Otolaryngology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Takaki Miwa
- Otolaryngology, Kanazawa Medical University, Ishikawa, Japan
| | - Paul J Moberg
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Sagar U Nigwekar
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Erin K O'Brien
- Otolaryngology, Mayo Clinic Rochester, Rochester, Minnesota, USA
| | - Teodor G Paunescu
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Carl Philpott
- Otolaryngology, University of East Anglia, Norwich, UK
| | - Jayant M Pinto
- Otolaryngology, University of Chicago, Chicago, Illinois, USA
| | - Evan R Reiter
- Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - David R Roalf
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nicholas R Rowan
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rodney J Schlosser
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - James Schwob
- Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Allen M Seiden
- Otolaryngology, University of Cincinnati School of Medicine, Cincinnati, Ohio, USA
| | - Timothy L Smith
- Otolaryngology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Zachary M Soler
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - Leigh Sowerby
- Otolaryngology, University of Western Ontario, London, Ontario, Canada
| | - Bruce K Tan
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Andrew Thamboo
- Otolaryngology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bozena Wrobel
- Otolaryngology, Keck School of Medicine, USC, Los Angeles, California, USA
| | - Carol H Yan
- Otolaryngology, School of Medicine, UCSD, La Jolla, California, USA
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11
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Helman SN, Adler J, Jafari A, Bennett S, Vuncannon JR, Cozart AC, Wise SK, Kuruvilla ME, Levy JM. Treatment strategies for postviral olfactory dysfunction: A systematic review. Allergy Asthma Proc 2022; 43:96-105. [PMID: 35317886 DOI: 10.2500/aap.2022.43.210107] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Background: The coronavirus disease 2019 (COVID-19) pandemic has been associated with a dramatic increase in postviral olfactory dysfunction (PVOD) among patients who are infected. A contemporary evidence-based review of current treatment options for PVOD is both timely and relevant to improve patient care. Objective: This review seeks to impact patient care by qualitatively reviewing available evidence in support of medical and procedural treatment options for PVOD. Systematic evaluation of data quality and of the level of evidence was completed to generate current treatment recommendations. Methods: A systematic review was conducted to identify primary studies that evaluated treatment outcomes for PVOD. A number of medical literature data bases were queried from January 1998 to May 2020, with completion of subsequent reference searches of retrieved articles to identify all relevant studies. Validated tools for the assessment of bias among both interventional and observational studies were used to complete quality assessment. The summary level of evidence and associated outcomes were used to generate treatment recommendations. Results: Twenty-two publications were identified for qualitative review. Outcomes of alpha-lipoic acid, intranasal and systemic corticosteroids, minocycline, zinc sulfate, vitamin A, sodium citrate, caroverine, intranasal insulin, theophylline, and Gingko biloba are reported. In addition, outcomes of traditional Chinese acupuncture and olfactory training are reviewed. Conclusion: Several medical and procedural treatments may expedite the return of olfactory function after PVOD. Current evidence supports olfactory training as a first-line intervention. Additional study is required to define specific treatment recommendations and expected outcomes for PVOD in the setting of COVID-19.
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Affiliation(s)
- Samuel N. Helman
- From the Department of Otolaryngology - Head and Neck Surgery, Weill Cornell Medical College, New York, New York
| | - Jonah Adler
- School of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Aria Jafari
- Department of Otolaryngology - Head and Neck Surgery, University of Washington, Seattle, Washington
| | - Sasha Bennett
- School of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jackson R. Vuncannon
- Department of Otolaryngology - Head and Neck Surgery, Emory University School of Medicine, Atlanta, Georgia
| | - Ashley C. Cozart
- College of Medicine, University of Central Florida College of Medicine, Orlando, Florida; and
| | - Sarah K. Wise
- Department of Otolaryngology - Head and Neck Surgery, Emory University School of Medicine, Atlanta, Georgia
| | - Merin E. Kuruvilla
- Division of Pulmonary, Allergy, Critical Care, and Sleep, Emory University School of Medicine, Atlanta, Georgia
| | - Joshua M. Levy
- Department of Otolaryngology - Head and Neck Surgery, Emory University School of Medicine, Atlanta, Georgia
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12
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Abstract
Purpose of Review Olfactory dysfunction is a prevalent condition affecting 5–15% of the general population, with significant impact on quality of life. This review summarizes the most recent and relevant literature in the treatment of olfactory dysfunction. Recent Findings Current evidence supports the short-term use of topical corticosteroids and systemic therapy. These treatments may occur in conjunction with olfactory training, which is well supported by the literature. While there are several additional treatments currently under investigation, meaningful conclusions are not yet able to be made regarding their efficacy. Summary The treatment of olfactory dysfunction is targeted at the suspected etiology when possible. After normal aging, chronic rhinosinusitis, post-infectious sequelae including as a result SARS-CoV-2 infection (COVID-19), and head trauma are the most common causes. Current evidence supports the short-term use of topical corticosteroids and systemic therapy. Several additional treatments are under investigation but recommendations for their use cannot currently be made. Graphical abstract ![]()
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Affiliation(s)
- Aria Jafari
- Department of Otolaryngology-Head & Neck Surgery, Division of Rhinology and Endoscopic Skull Base Surgery, University of Washington, Seattle, WA, 98195-6515, USA.
| | - Eric H Holbrook
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA, USA
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13
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Abstract
Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.
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Affiliation(s)
- M M Speth
- Klinik für Hals‑, Nasen‑, Ohrenkrankheiten, Hals- und Gesichtschirurgie, Kantonsspital Aarau, Aarau, Schweiz.
| | - U S Speth
- Klinik für Mund‑, Kiefer-, und Gesichtschirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Deutschland
| | - A R Sedaghat
- Department of Otolaryngology - Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, USA
| | - T Hummel
- Universitäts-HNO Klinik, TU Dresden, Dresden, Deutschland
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14
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Khani E, Khiali S, Beheshtirouy S, Entezari-Maleki T. Potential pharmacologic treatments for COVID-19 smell and taste loss: A comprehensive review. Eur J Pharmacol 2021; 912:174582. [PMID: 34678243 PMCID: PMC8524700 DOI: 10.1016/j.ejphar.2021.174582] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/08/2021] [Accepted: 10/18/2021] [Indexed: 12/30/2022]
Abstract
The acute loss of taste and smell following COVID-19 are hallmark symptoms that affect 20-85% of patients. However, the pathophysiology and potential treatments of COVID-19 smell and taste loss are not fully understood. We searched the literature to review the potential pathologic pathways and treatment options for COVID-19 smell and taste loss. The interaction of novel coronavirus with ACE-2 receptors expressed on sustentacular cells and taste buds results in direct damage to the olfactory and gustatory systems. Also, the invasion of the virus to the olfactory neurons and consequent local inflammation are other proposed mechanisms. Therefore, COVID-19 patients with smell or taste loss may benefit from neuroprotective, anti-inflammatory, or depolarizing agents. Based on the current evidence, phosphodiesterase inhibitors, insulin, and corticosteroids can be promising for the management of COVID-19 smell and taste loss. This review provided crucial information for treating COVID-19-related smell and/or taste loss, urging to perform large clinical trials to find optimum treatment options.
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Affiliation(s)
- Elnaz Khani
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Sajad Khiali
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Samineh Beheshtirouy
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Taher Entezari-Maleki
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran,Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran,Corresponding author. Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, P.O. Box: 51664-14766 12, Iran
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15
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Poessel M, Morys F, Breuer N, Villringer A, Hummel T, Horstmann A. Brain response to food odors is not associated with body mass index and obesity-related metabolic health measures. Appetite 2021; 168:105774. [PMID: 34715246 DOI: 10.1016/j.appet.2021.105774] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 09/17/2021] [Accepted: 10/22/2021] [Indexed: 12/14/2022]
Abstract
Smell perception plays a role in eating behavior and might be involved in the development of obesity. In fact, olfactory function is impaired in obesity and might depend on metabolic health factors. To date, the underlying neural mechanisms remain unclear. Here, we investigate neural processing of food-related odors in normal-weight, overweight and obese individuals. Fifty-three young and healthy participants (28.8 ± 4.4 years, 27 female; 24 normal-weight, 10 overweight, and 19 obese) were presented with high- (chocolate, potato chips) and low-caloric (orange, cucumber) food odors during a functional magnetic resonance imaging (fMRI). We also assessed olfactory identification ability, body mass index (BMI), body fat percentage, insulin resistance, and leptin levels. In brief, olfactory perception of food odors was linked to brain activity in the entorhinal and piriform cortex, and the insula, hippocampus, and amygdala. Insulin resistance was negatively related to olfactory identification. Additionally, perception of sweet versus savory odors was related to a higher brain activity in the right middle/superior frontal gyrus. Finally, we found no effect of obesity status, BMI, metabolic factors, or body fat percentage on neural responses to food odors. Overall, this suggests that food odor processing might depend on factors other than body weight status or associated markers of metabolic health.
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Affiliation(s)
- Maria Poessel
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103, Leipzig, Germany; IFB AdiposityDiseases, Leipzig University Medical Center, Philipp-Rosenthal-Str. 27, 04103, Leipzig, Germany.
| | - Filip Morys
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103, Leipzig, Germany; Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada
| | - Nora Breuer
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103, Leipzig, Germany; IFB AdiposityDiseases, Leipzig University Medical Center, Philipp-Rosenthal-Str. 27, 04103, Leipzig, Germany
| | - Arno Villringer
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103, Leipzig, Germany; Day Clinic for Cognitive Neurology, University Hospital at the University of Leipzig, Liebigstraße 16, 04103, Leipzig, Germany; Mind Brain Body Institute, Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, 10099, Berlin, Germany; Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany; International Max Planck Research School on the Life Course, Max Planck Institute for Human Development, Lentzeallee 94, 14195, Berlin, Germany; International Max Planck Research School on the Neuroscience of Communication, Max Planck Institute for Human Cognitive and Brain Sciences, P.O. Box 500355, 04103, Leipzig, Germany
| | - Thomas Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Annette Horstmann
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103, Leipzig, Germany; IFB AdiposityDiseases, Leipzig University Medical Center, Philipp-Rosenthal-Str. 27, 04103, Leipzig, Germany; Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Haartmaninkatu 3, 00290, Helsinki, Finland
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16
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Berro C, Pendolino AL, Foletto M, Facciolo MC, Maculan P, Prevedello L, Giuntoli DG, Scarpa B, Pavan C, Andrews PJ, Ottaviano G. Olfactory and Gustatory Function before and after Laparoscopic Sleeve Gastrectomy. ACTA ACUST UNITED AC 2021; 57:medicina57090913. [PMID: 34577836 PMCID: PMC8466191 DOI: 10.3390/medicina57090913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/18/2021] [Accepted: 08/26/2021] [Indexed: 01/09/2023]
Abstract
Background and Objectives: Bariatric surgery is the gold standard for the treatment of morbid obesity, and current evidence suggests that patients undergoing surgery can show changes in their sense of taste and smell. However, no definitive conclusions can be drawn given the heterogeneity of the studies and the contrasting results reported in the literature. Materials and Methods: We enrolled 18 obese patients undergoing laparoscopic sleeve gastrectomy (LSG) and 15 obese controls. At baseline (T0) and 6 months after enrollment/surgery (T1), both groups underwent Sniffin’ Sticks and whole mouth test. Post-operative qualitative taste variations were also analyzed and SNOT-22, VAS for taste and smell, and MMSE were administered. Results: An improvement in the olfactory threshold was observed in the treatment group (p = 0.03) at 6 months. At multivariate analysis, the olfactory threshold differences observed correlated with MMSE (p = 0.03) and T0 gustatory identification (p = 0.01). No changes in sense of taste were observed between the two groups at 6 months, even though nine subjects in the treatment group reported a worsening of taste. This negatively correlated with age (p < 0.001), but a positive marginal correlation was observed with the olfactory threshold difference between T0 and T1 (p = 0.06). Conclusions: Olfaction can improve after LSG, and this seems to be the consequence of an improved olfactory threshold. Although we did not observe any change in gustatory identification, food’s pleasantness worsened after bariatric surgery.
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Affiliation(s)
- Cecilia Berro
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Alfonso Luca Pendolino
- Department of ENT, Royal National ENT & Eastman Dental Hospitals, London WC1E 6DG, UK;
- Ear Institute, University College London, London WC1X 8EE, UK
- Correspondence:
| | - Mirto Foletto
- Centre for Mechanics of Biological Materials, University of Padova, 35128 Padova, Italy;
- IFSO Bariatric Centre of Excellence, Padova University Hospital, 35128 Padova, Italy;
| | - Maria Cristina Facciolo
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Pietro Maculan
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padova, 35128 Padova, Italy;
| | - Luca Prevedello
- IFSO Bariatric Centre of Excellence, Padova University Hospital, 35128 Padova, Italy;
| | - Diletta Giulia Giuntoli
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Bruno Scarpa
- Department of Statistical Sciences and Department of Mathematics Tullio Levi-Civita, University of Padova, 35128 Padova, Italy;
| | - Chiara Pavan
- Department of Psychiatry, University of Padua, 35128 Padua, Italy;
| | - Peter J. Andrews
- Department of ENT, Royal National ENT & Eastman Dental Hospitals, London WC1E 6DG, UK;
- Ear Institute, University College London, London WC1X 8EE, UK
| | - Giancarlo Ottaviano
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
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17
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Flavor Enhancement in Daily Life of Patients with Olfactory Dysfunction. CHEMOSENS PERCEPT 2021. [DOI: 10.1007/s12078-021-09289-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Abstract
Introduction
Patients with olfactory dysfunction report deterioration of taste due to loss of flavor, leading to less food enjoyment, alterations in dietary behaviors and stress. The aim of this study was to introduce flavor enhancement to investigate its acceptance and possible effects on quality of life.
Methods
In this prospective, controlled, randomized, single-blinded, cross-over pilot study, we recruited 30 olfactory dysfunction patients, of which 16 were hyposmic and 14 anosmic. After single-blinded triangle flavor discrimination test, flavor drops were randomized either in high or low concentration for 14 days and vice versa for another 14 days. Records included a daily diary and the questionnaire of olfactory disorders.
Results
Usage rates were excellent with 82.2% of all days, while drops were mainly used for breakfast (44.6%, p < 0.05). Hyposmics used flavor enhancement on significantly more days (median = 14) compared to anosmics (median = 11, p = 0.0094). QOD improved in 12 patients to a meaningful extent.
Conclusions
In this pilot study, we show that flavor enhancement is feasible accompanied by high compliance and acceptance in olfactory dysfunction patients. Flavor drops were used regardless of low or high concentrations with no adverse events noted.
Implications
Our findings give rise to further studies illuminating the possible advantages of flavor enhancement in patients with olfactory disorders.
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18
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Intranasal insulin and orexins to treat age-related cognitive decline. Physiol Behav 2021; 234:113370. [PMID: 33621561 DOI: 10.1016/j.physbeh.2021.113370] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 02/19/2021] [Indexed: 02/06/2023]
Abstract
The intranasal (IN) administration of neuropeptides, such as insulin and orexins, has been suggested as a treatment strategy for age-related cognitive decline (ARCD). Because dysfunctional neuropeptide signaling is an observed characteristic of ARCD, it has been suggested that IN delivery of insulin and/or orexins may restore endogenous peptide signaling and thereby preserve cognition. IN administration is particularly alluring as it is a relatively non-invasive method that directly targets peptides to the brain. Several laboratories have examined the behavioral effects of IN insulin in young, aged, and cognitively impaired rodents and humans. These studies demonstrated improved performance on various cognitive tasks following IN insulin administration. Fewer laboratories have assessed the effects of IN orexins; however, this peptide also holds promise as an effective treatment for ARCD through the activation of the cholinergic system and/or the reduction of neuroinflammation. Here, we provide a brief overview of the advantages of IN administration and the delivery pathway, then summarize the current literature on IN insulin and orexins. Additional preclinical studies will be useful to ultimately uncover the mechanisms underlying the pro-cognitive effects of IN insulin and orexins, whereas future clinical studies will aid in the determination of the most efficacious dose and dosing paradigm. Eventually, IN insulin and/or orexin administration may be a widely used treatment strategy in the clinic for ARCD.
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19
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Bryche B, Baly C, Meunier N. Modulation of olfactory signal detection in the olfactory epithelium: focus on the internal and external environment, and the emerging role of the immune system. Cell Tissue Res 2021; 384:589-605. [PMID: 33961125 PMCID: PMC8102665 DOI: 10.1007/s00441-021-03467-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/26/2021] [Indexed: 12/18/2022]
Abstract
Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing environment. Part of these adaptations includes changes of odorant detection by olfactory sensory neurons localized in the olfactory epithelium. It is now well established that internal signals such as hormones, neurotransmitters, or paracrine signals directly affect the electric activity of olfactory neurons. Furthermore, recent data have shown that activity-dependent survival of olfactory neurons is important in the olfactory epithelium. Finally, as olfactory neurons are directly exposed to environmental toxicants and pathogens, the olfactory epithelium also interacts closely with the immune system leading to neuroimmune modulations. Here, we review how detection of odorants can be modulated in the vertebrate olfactory epithelium. We choose to focus on three cellular types of the olfactory epithelium (the olfactory sensory neuron, the sustentacular and microvillar cells) to present the diversity of modulation of the detection of odorant in the olfactory epithelium. We also present some of the growing literature on the importance of immune cells in the functioning of the olfactory epithelium, although their impact on odorant detection is only just beginning to be unravelled.
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Affiliation(s)
- Bertrand Bryche
- Université Paris-Saclay, INRAE, UVSQ, 78350, Jouy-en-Josas, VIM, France
| | - Christine Baly
- Université Paris Saclay, INRAE, UVSQ, BREED, 78350, Jouy-en-Josas, France
| | - Nicolas Meunier
- Université Paris-Saclay, INRAE, UVSQ, 78350, Jouy-en-Josas, VIM, France.
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20
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Mohamad SA, Badawi AM, Mansour HF. Insulin fast-dissolving film for intranasal delivery via olfactory region, a promising approach for the treatment of anosmia in COVID-19 patients: Design, in-vitro characterization and clinical evaluation. Int J Pharm 2021; 601:120600. [PMID: 33862126 DOI: 10.1016/j.ijpharm.2021.120600] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/05/2021] [Accepted: 04/08/2021] [Indexed: 12/12/2022]
Abstract
The present work aimed to formulate intranasal insulin fast-dissolving films for treatment of anosmia in patients post COVID-19 infection. Variant films were prepared employing the casting method and using hydroxypropyl methyl cellulose and polyvinyl alcohol. The formulated films were investigated for insulin content, weight variation, surface pH, thickness, folding endurance and disintegration time. In vitro release study was conducted for the selected formulations (F6, F7, F8). A drug/polymer interaction was investigated in the optimized formulation (F7) employing Fourier transform infrared spectroscopy. Clinical study was accomplished for F7 on 20 patients. Sniffin's and olfactory discrimination tests were used for assessing patients. The formulated films displayed appropriate physical characteristics. F7 showed the shortest disintegration time (50 ± 7 s) and fastest release. It displayed compatibility between the drug and the used polymers. The results of the clinical study revealed a significant increase in the olfactory detection scores and olfactory discrimination values in the intervention group (7.9 ± 1.2, 6.7 ± 0.5 respectively) compared to placebo group (3 ± 0.8, 2.8 ± 1).. Intervention group showed significant differences between these scores before and after treatment while the placebo group did not display any significant differences. Thus, the optimized film can be considered as an auspicious approach for managing post COVID-19 anosmia.
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Affiliation(s)
- Soad A Mohamad
- Department of Pharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, Deraya University, Minia, Egypt
| | - Ahmed M Badawi
- Department of Otorhinolaryngology, Faculty of Medicine, Minia University, Minia, Egypt
| | - Heba F Mansour
- Department of Pharmaceutics, Faculty of Pharmacy, Minia University, Minia, Egypt.
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21
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Abstract
Approximately 5% of the general population is affected by functional anosmia with approximately additional 15% exhibiting decreased olfactory function. Many of these individuals ask for help. Because the subjective rating of olfactory function is biased, assessment of olfactory function is important. Olfactory measurements are needed for patient counseling and the tracking of changes in the sense of smell over time. The present review provides an overview of frequently used psychophysical tests for olfactory function, discusses differences between threshold and suprathreshold aspects of olfactory function, and gives examples on how to apply psychophysical tests.
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Affiliation(s)
- Thomas Hummel
- Department of Otorhinolaryngology, Smell & Taste Clinic, "Technische Universität Dresden", Dresden, Germany
| | - Dino Podlesek
- Department of Neurosurgery, "Technische Universität Dresden", Dresden, Germany
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22
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Menghi L, Khomenko I, Pedrotti M, Cliceri D, Aprea E, Endrizzi I, Cavazzana A, Biasioli F, Giacalone D, Gasperi F. Arousal influences olfactory abilities in adults with different degree of food neophobia. Sci Rep 2020; 10:20538. [PMID: 33239637 PMCID: PMC7689524 DOI: 10.1038/s41598-020-77428-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/10/2020] [Indexed: 11/24/2022] Open
Abstract
Food neophobia, i.e., the aversion to novel foods, and olfaction are both factors strongly affecting food choices. Mounting evidence suggests a higher arousal towards food as a key factor underlying the reluctance to eat what is unfamiliar to us. As the role of olfaction behind this phenomenon is poorly understood, we explored the associations between food neophobia and trait anxiety, olfactory functions (odor threshold, discrimination and identification) and retronasal aroma release from a reference food in a healthy cohort of 83 adult volunteers. We grouped participants in Low-Neophobics or neophilics (n = 35), Medium-Neophobics (n = 32) and High-Neophobics (n = 16) according to the widely recognized Food Neophobia Scale. Participants with higher neophobic tendencies were found to have marginally higher trait anxiety levels than neophilics (p = 0.10). A lower global olfactory functioning and odor discrimination abilities characterized High-Neophobics, while Medium-Neophobics showed a higher odor sensitiveness than Low-Neophobics. Lastly, High-Neophobics showed a lower extent of retronasal aroma release, likely due to a shorter duration of oral processing and higher anxiety-related physiological responses (such as breathing rate). In summary, this study supports the assumption that the conflicting relationship that neophobics have with food may be led by higher levels of arousal toward foods, rather than different chemosensory functions.
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Affiliation(s)
- Leonardo Menghi
- Center Agriculture Food Environment, University of Trento, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy.,Department of Technology and Innovation, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark.,Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Iuliia Khomenko
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Michele Pedrotti
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy.,Department of Food Quality and Design, Wageningen University, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands
| | - Danny Cliceri
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Eugenio Aprea
- Center Agriculture Food Environment, University of Trento, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy.,Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Isabella Endrizzi
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Annachiara Cavazzana
- Department of Otorhinolaryngology, Smell and Taste Clinic, Technische Universität Dresden, Fetscherstraße 74, 01307, Dresden, Germany
| | - Franco Biasioli
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy
| | - Davide Giacalone
- Department of Technology and Innovation, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
| | - Flavia Gasperi
- Center Agriculture Food Environment, University of Trento, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy. .,Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach, 1, 38010, San Michele all'Adige, TN, Italy.
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23
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Hura N, Xie DX, Choby GW, Schlosser RJ, Orlov CP, Seal SM, Rowan NR. Treatment of post-viral olfactory dysfunction: an evidence-based review with recommendations. Int Forum Allergy Rhinol 2020; 10:1065-1086. [PMID: 32567798 PMCID: PMC7361320 DOI: 10.1002/alr.22624] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/07/2020] [Accepted: 05/12/2020] [Indexed: 12/29/2022]
Abstract
Background Post‐viral olfactory dysfunction (PVOD) is one of the most common causes of olfactory loss. Despite its prevalence, optimal treatment strategies remain unclear. This article provides a comprehensive review of PVOD treatment options and provides evidence‐based recommendations for their use. Methods A systematic review of the Medline, Embase, Cochrane, Web of Science, Scopus, and Google Scholar databases was completed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Studies with defined olfactory outcomes of patients treated for PVOD following medical, surgical, acupuncture, or olfactory training interventions were included. The Clinical Practice Guideline Development Manual and Conference on Guideline Standardization (COGS) instrument recommendations were followed in accordance with a previously described, rigorous, iterative process to create an evidence‐based review with recommendations. Results From 552 initial candidate articles, 36 studies with data for 2183 patients with PVOD were ultimately included. The most common method to assess olfactory outcomes was Sniffin’ Sticks. Broad treatment categories included: olfactory training, systemic steroids, topical therapies, a variety of heterogeneous non‐steroidal oral medications, and acupuncture. Conclusion Based on the available evidence, olfactory training is a recommendation for the treatment of PVOD. The use of short‐term systemic and/or topical steroids is an option in select patients after careful consideration of potential risks of oral steroids. Though some pharmacological investigations offer promising preliminary results for systemic and topical medications alike, a paucity of high‐quality studies limits the ability to make meaningful evidence‐based recommendations for the use of these therapies for the treatment of PVOD.
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Affiliation(s)
- Nanki Hura
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Deborah X Xie
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Garret W Choby
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic College of Medicine, Rochester, MN
| | - Rodney J Schlosser
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC
| | - Cinthia P Orlov
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Stella M Seal
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Nicholas R Rowan
- Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
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Dicker D, Beck A, Markel A, Marcovicu D, Mazzawi S, Sarid M, Greenberg E, Atkinson RL. Weight Loss, Dietary Preferences, and Reduction in the Sense of Smell with the Use of a Novel Nasal Device. Obes Facts 2020; 13:473-486. [PMID: 32950989 PMCID: PMC7670359 DOI: 10.1159/000508976] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/19/2020] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION Exposure to food odors are known to increase food intake. Olfaction declines from age 50 years. OBJECTIVE We examined changes in the sense of smell, body weight, food preferences, and parameters of metabolic status, following the use of a specially designed nasal device. METHODS This is a randomized, placebo-controlled study. Participants wore a nasal device (soft silicone insert) for 5-12 h daily (device group) or inserted 2 drops of normal saline into each nostril daily (control group). Follow-up visits occurred every 2 weeks. All participants were given a 500 kcal/day reduced diet and instructed not to change their regular physical activity. Weight, food preferences, olfactory sensitivity, and blood tests were performed at baseline and after 12 weeks. RESULTS Of 156 participants, 65 (42%) completed the study. Sense of smell decreased in the device group (from 6.4 ± 0.9 to 4.4 ± 1.5, on a scale of 0-7, p < 0.001), and did not change in the control group. Weight loss decreased by 6.6 ± 3.7% (p = 0.001) and by 5.7 ± 3.5% (p = 0.001) in the respective groups (between-group difference, p > 0.05). Among participants aged ≤50 years, weight loss was greater in the device than in the control group (7.7 ± 4.2% vs. 4.1 ± 2.9%, p = 0.02). Insulin level and the homeostatic model assessment of insulin resistance (HOMA-IR) were significantly reduced in the device group (p = 0.02 and p = 0.01, respectively), but not in the control group. Food preferences for sugar (p < 0.02), sweet beverages (p < 0.001), and artificial sweeteners (p < 0.02) were significantly reduced in the device group compared to the control group. CONCLUSIONS The use of a novel self-administrated nasal device led to reduced olfactory sensitivity, improved insulin sensitivity, weight loss, and lesser preference for sweets in adults aged ≤50 years.
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Affiliation(s)
- Dror Dicker
- Internal Medicine D and Obesity Clinic, Hasharon Hospital, Rabin Medical Center, Petach-Tikva, Israel,
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel,
| | | | | | - Dana Marcovicu
- Internal Medicine D and Obesity Clinic, Hasharon Hospital, Rabin Medical Center, Petach-Tikva, Israel
| | - Salim Mazzawi
- Otolaryngology Head and Neck Surgery, Haemek Medical Center, Rappaport School of Medicine, Technion, Israel
| | | | | | - Richard L Atkinson
- Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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25
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The role of insulin sensitivity and intranasally applied insulin on olfactory perception. Sci Rep 2019; 9:7222. [PMID: 31076634 PMCID: PMC6510903 DOI: 10.1038/s41598-019-43693-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 04/30/2019] [Indexed: 01/24/2023] Open
Abstract
Olfactory perception determines food selection behavior depending on energy homeostasis and nutritional status. The mechanisms, however, by which metabolic signals in turn regulate olfactory perception remain largely unclear. Given the evidence for direct insulin action on olfactory neurons, we tested olfactory performance (olfactory threshold, olfactory discrimination) in 36 subjects of normal- and overweight after administration of three different insulin doses (40 I.U., 100 I.U., 160 I.U.) or corresponding placebo volume in a within-subject design. Poor peripheral insulin sensitivity as quantified by HOMA-IR in baseline condition and increases in systemic insulin levels reactive to intranasal administration predicted poor olfactory performance. In contrast, intranasal insulin enhanced odor perception with a dose-dependent improvement of olfactory threshold. These findings indicate a new diametric impact of insulin on olfactory perception depending on peripheral or central availability.
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Koskinen K, Reichert JL, Hoier S, Schachenreiter J, Duller S, Moissl-Eichinger C, Schöpf V. The nasal microbiome mirrors and potentially shapes olfactory function. Sci Rep 2018; 8:1296. [PMID: 29358754 PMCID: PMC5778015 DOI: 10.1038/s41598-018-19438-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/29/2017] [Indexed: 02/07/2023] Open
Abstract
Olfactory function is a key sense for human well-being and health, with olfactory dysfunction having been linked to serious diseases. As the microbiome is involved in normal olfactory epithelium development, we explored the relationship between olfactory function (odor threshold, discrimination, identification) and nasal microbiome in 67 healthy volunteers. Twenty-eight subjects were found to have normal olfactory function, 29 had a particularly good sense of smell ("good normosmics") and 10 were hyposmic. Microbial community composition differed significantly between the three olfactory groups. In particular, butyric acid-producing microorganisms were found to be associated with impaired olfactory function. We describe the first insights of the potential interplay between the olfactory epithelium microbial community and olfactory function, and suggest that the microbiome composition is able to mirror and potentially shape olfactory function by producing strong odor compounds.
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Affiliation(s)
- Kaisa Koskinen
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Johanna L Reichert
- BioTechMed-Graz, Graz, Austria
- Institute of Psychology, University of Graz, Graz, Austria
| | - Stefan Hoier
- Hanusch Krankenhaus Vienna, Department of Otorhinolaryngology, Head and Neck Surgery, Vienna, Austria
| | | | - Stefanie Duller
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Christine Moissl-Eichinger
- Department of Internal Medicine, Medical University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Veronika Schöpf
- BioTechMed-Graz, Graz, Austria.
- Institute of Psychology, University of Graz, Graz, Austria.
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Rodriguez-Raecke R, Brünner YF, Kofoet A, Mutic S, Benedict C, Freiherr J. Odor Sensitivity After Intranasal Insulin Application Is Modulated by Gender. Front Endocrinol (Lausanne) 2018; 9:580. [PMID: 30356884 PMCID: PMC6190874 DOI: 10.3389/fendo.2018.00580] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 09/12/2018] [Indexed: 11/13/2022] Open
Abstract
Obesity constitutes a global health care problem, and often eating habits are to blame. For intervention, a thorough understanding of energy intake and expenditure is needed. In recent years, the pivotal role of insulin in connection to energy intake was established. Olfactory sensitivity may be a target of cerebral insulin action to maintain body weight. With this experiment, we aimed to explore the influence of intranasal insulin on olfactory sensitivity for the odors n-butanol and peanut in a placebo-controlled, double-blind setting in a within-subject design. All subjects participated in two experimental sessions on separate days and received either intranasal insulin or placebo in a pseudorandomized order. Application was followed by two olfactory threshold tests for n-butanol and peanut in a pseudorandomized order. After a single dose of intranasal insulin (40 IU) or placebo (0.4 ml), olfactory sensitivity for the odorants n-butanol and peanut were examined in 30 healthy normosmic participants (14 females). Measured blood parameters revealed no decrease in plasma glucose, however, insulin, leptin and cortisol levels were affected following intranasal application. Females' but not males' olfactory sensitivity for n-butanol was lower after intranasal insulin administration vs. placebo. In contrast, olfactory sensitivity for peanut was not influenced by intranasal insulin application. Our results indicate that the effects of cortical insulin levels on processing of specific odors is likely modulated by gender, as central increase of insulin concentration led to a reduced olfactory sensitivity for n-butanol in women only, which might be due to differentially regulated insulin and leptin signaling in men and women.
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Affiliation(s)
- Rea Rodriguez-Raecke
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
- Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
- *Correspondence: Rea Rodriguez-Raecke
| | - Yvonne F. Brünner
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Anja Kofoet
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Smiljana Mutic
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
| | | | - Jessica Freiherr
- Diagnostic and Interventional Neuroradiology, University Hospital, RWTH Aachen University, Aachen, Germany
- Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
- Jessica Freiherr
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Bell GA, Fadool DA. Awake, long-term intranasal insulin treatment does not affect object memory, odor discrimination, or reversal learning in mice. Physiol Behav 2017; 174:104-113. [PMID: 28259806 PMCID: PMC5639911 DOI: 10.1016/j.physbeh.2017.02.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 02/23/2017] [Accepted: 02/28/2017] [Indexed: 12/17/2022]
Abstract
Intranasal insulin delivery is currently being used in clinical trials to test for improvement in human memory and cognition, and in particular, for lessening memory loss attributed to neurodegenerative diseases. Studies have reported the effects of short-term intranasal insulin treatment on various behaviors, but less have examined long-term effects. The olfactory bulb contains the highest density of insulin receptors in conjunction with the highest level of insulin transport within the brain. Previous research from our laboratory has demonstrated that acute insulin intranasal delivery (IND) enhanced both short- and long-term memory as well as increased two-odor discrimination in a two-choice paradigm. Herein, we investigated the behavioral and physiological effects of chronic insulin IND. Adult, male C57BL6/J mice were intranasally treated with 5μg/μl of insulin twice daily for 30 and 60days. Metabolic assessment indicated no change in body weight, caloric intake, or energy expenditure following chronic insulin IND, but an increase in the frequency of meal bouts selectively in the dark cycle. Unlike acute insulin IND, which has been shown to cause enhanced performance in odor habituation/dishabituation and two-odor discrimination tasks in mice, chronic insulin IND did not enhance olfactometry-based odorant discrimination or olfactory reversal learning. In an object memory recognition task, insulin IND-treated mice did not perform differently than controls, regardless of task duration. Biochemical analyses of the olfactory bulb revealed a modest 1.3 fold increase in IR kinase phosphorylation but no significant increase in Kv1.3 phosphorylation. Substrate phosphorylation of IR kinase downstream effectors (MAPK/ERK and Akt signaling) proved to be highly variable. These data indicate that chronic administration of insulin IND in mice fails to enhance olfactory ability, object memory recognition, or a majority of systems physiology metabolic factors - as reported to elicit a modulatory effect with acute administration. This leads to two alternative interpretations regarding long-term insulin IND in mice: 1) It causes an initial stage of insulin resistance to dampen the behaviors that would normally be modulated under acute insulin IND, but ability to clear a glucose challenge is still retained, or 2) There is a lack of behavioral modulation at high concentration of insulin attributed to the twice daily intervals of hyperinsulinemia caused by insulin IND administration without any insulin resistance, per se.
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Affiliation(s)
- Genevieve A Bell
- Department of Biological Science and Program in Neuroscience, The Florida State University, Tallahassee, FL 32306-4295, United States
| | - Debra Ann Fadool
- Department of Biological Science and Program in Neuroscience, The Florida State University, Tallahassee, FL 32306-4295, United States; Institute of Molecular Biophysics, The Florida State University, Tallahassee, FL 32306-4380, United States.
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Longer latency of sensory response to intravenous odor injection predicts olfactory neural disorder. Sci Rep 2016; 6:35361. [PMID: 27734933 PMCID: PMC5062120 DOI: 10.1038/srep35361] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/28/2016] [Indexed: 11/08/2022] Open
Abstract
A near loss of smell may result from conductive and/or neural olfactory disorders. However, an olfactory test to selectively detect neural disorders has not been established. We investigated whether onset latency of sensory response to intravenous odor injection can detect neural disorders in humans and mice. We showed that longer preoperative onset latency of odor recognition to intravenous odor in patients with chronic rhinosinusitis predicted worse recovery of olfactory symptoms following sinus surgery. The onset latency of the olfactory sensory neuron (OSN) response to intravenous odor using synaptopHluorin signals from OSN axon terminals was delayed in mice with reduced numbers of OSNs (neural disorder) but not with increased mucus or blocked orthonasal pathways (conductive disorders). Moreover, the increase in onset latency correlated with the decrease in mature OSN numbers. Longer onset latency to intravenous odor injection is a useful biomarker for presence and severity of olfactory disorders with neural etiology.
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