Identifying Pharmaceutical-Grade Essential Oils and Using Them Safely and Effectively in Integrative Medicine
Aruna Bakhru in Nutrition and Integrative Medicine, 2018
Essential oils are unique remedies because they simultaneously influence psychological, biological, and cognitive health. The sense of smell—10,000 times more powerful than the sense of taste—is the only of the major senses that is directly connected to the brain (through the olfactory bulb). Airborne odor molecules enter the nostrils and dissolve in the nasal mucosa. Under the nasal mucosa, olfactory receptor neurons detect the odor molecules and transmit information to the olfactory bulb at the back of the nasal cavity. Sensory receptors of the olfactory bulb are part of the brain and send messages to the most primitive brain centers (limbic system structures) and the neo-cortex, which influence memory, emotions, and conscious thought. Therefore, the administration of essential oils produces a complete psychophysiological response that causes automatic adaptations by the central nervous system.
Chemosensation
Emily Crews Splane, Neil E. Rowland, Anaya Mitra in Psychology of Eating, 2019
The chemical analysis of odorant molecules is performed by detectors called olfactory receptors that are clustered on the dendrites of olfactory receptor neurons that are embedded in the olfactory epithelium, a specialized structure lining the roof of the nasal cavity, about 3 cm x 3 cm in humans (Figure 5.1). Although small in size, this sensory surface expresses some 400 distinct olfactory receptors all of which belong to a superfamily called G-protein coupled receptors (GPCRs). GPCRs are protein chains of at least 300 amino acids that thread through the cell membrane seven times forming three domains or loops outside the cell that define a specific size and shape of pocket or “nest” for binding their ligands. Different GPCRs have different amino acid sequences in these loops that yield different shaped pockets. Some of these receptors seem to have a high threshold for activation and respond to a relatively narrow range of odorant shapes while others seem to have low threshold for activation but respond to a broad range of odorant shapes (Yu et al., 2015).
Outdoor Air Pollution
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
A complex mixture of gases, PM, and chemicals present in outdoor and indoor air produces adverse health effects such as those seen in the chemically sensitive and chronic degenerative patients. Because the nasal cavity is a common portal of entry for such pollutants, the nasal olfactory and respiratory mucosa are vulnerable to damage and well-known targets for air pollutant-induced toxicity and carcinogenicity.304–307 The nose–brain barrier depends on intact epithelia, including tight junctions and an intact xenobiotic metabolizing capacity.308 Olfactory receptor cell dendrites are in direct contact with the environment, and, thus, pinocytosis and neuronal transport are likely routes of access to the CNS of potential toxins.309 Olfactory receptor neurons project from the sensory epithelium to targets within the olfactory bulb, the first synaptic relay in the olfactory pathway.309
Cellular and circuit mechanisms of olfactory associative learning in Drosophila
Published in Journal of Neurogenetics, 2020
Tamara Boto, Aaron Stahl, Seth M. Tomchik
The mushroom body (MB) is a critical anatomical structure involved in olfactory memory formation, as well as some types of visual and courtship memory (McBride et al., 1999; Vogt et al., 2014). The MB is situated in the olfactory pathway, as the tertiary structure, hierarchically similar to the mammalian amygdala or piriform cortex (Su, Menuz, & Carlson, 2009). Olfactory stimuli are initially detected by olfactory receptor neurons (ORNs) in the periphery, which transmits information to projection neurons (PNs), and subsequently the MB and another structure, the lateral horn (Davis, 2005; Fiala, 2007). The intrinsic MB neurons, also called Kenyon Cells (KCs), relay information to mushroom body output neurons (MBONs) (Aso et al., 2014a; Tanaka, Tanimoto, & Ito, 2008) via cholinergic synapses (Barnstedt et al., 2016). The MB is innervated by modulatory neurons, such as dopaminergic neurons (DANs), which are critical for learning and memory (Tanaka et al., 2008). This description includes the basic circuit elements (ORN→PN→KC→MBON; w/modulatory DANs) (Figure 1(A,B)), and will be further elaborated below. Note that while the general flow of information is most easily conceptualized as unidirectional, some of these connections exhibit both pre- and post-synaptic zones indicative of bidirectional communication (Christiansen et al., 2011; Pauls, Selcho, Gendre, Stocker, & Thum, 2010; Rolls et al., 2007) (Figure 1(C)). This bidirectional communication adds a layer of complexity with behavioral and computational implications that are largely unknown currently.
Extracellular vesicles isolated from human olfactory ensheathing cells enhance the viability of neural progenitor cells
Published in Neurological Research, 2020
Olfactory ensheathing cells (OECs) are a unique type of glia present in the lamina propria of the olfactory mucosa, the outer layer of the olfactory bulb, and both inner and outer layers of the nerve fiber [1,2]. OECs ensheathe non-myelinated primary olfactory axons and enhance neural regeneration by migrating and promoting olfactory sensory axon extension from the nasal epithelium towards the olfactory bulb [3,4]. These cells sustain continuous axon extension and successful topographic targeting of olfactory receptor neurons. Numerous studies have demonstrated that OECs support neural regeneration by stimulating axonal myelination [5], secreting important survival factors for regenerated axons such as neurotrophic factors [6–8] and extracellular matrix (ECM) molecules [9–11], and regulating cell debris phagocytosis [12] and neuroinflammation [13]. Thus, these cells play critical roles in neurogenesis and neural regeneration, which are specific features of the mammalian olfactory system. Because of their distinctive properties and autologous origin, transplantation of OECs has emerged as an alternative potential therapy for repairing central nervous system (CNS) damage, particularly for spinal cord injury [14].
Lipid nanoparticles for intranasal administration: application to nose-to-brain delivery
Published in Expert Opinion on Drug Delivery, 2018
Luigi Battaglia, Pier Paolo Panciani, Elisabetta Muntoni, Maria Teresa Capucchio, Elena Biasibetti, Pasquale De Bonis, Silvia Mioletti, Marco Fontanella, Shankar Swaminathan
The olfactory epithelia are the most likely site for direct nose-to-brain delivery: it chiefly consists of olfactory neural cells, the sustentacular (also known as supporting) cells, and the basal cells. Basal cells are progenitor cells (of supporting cells), that also provide mechanical support via anchorage to other cells. The olfactory neural cells or the axons are unmyelinated and interspaced between the supporting cells. They originate at the olfactory bulb in the brain and terminate at the apical surface of the olfactory epithelium. The olfactory knob protrudes out from and above the apical surface of the olfactory epithelium. Approximately 10–23 cilia project from the basal bodies of the knob, each of length up to 200 µm. The cilia are nonmotile in the olfactory region in contrast to respiratory region. The average diameter of olfactory axons in human is in the range 100–700 nm. Therefore, theoretically transcellular transport of NP is possible. In the olfactory region, neurons are interspersed among supporting cells and basal cells to form the olfactory epithelium [6]. Moreover, due to the direct contact with toxins in the external environment, olfactory receptor neurons regenerate every 3–4 weeks from basal cells residing in the olfactory epithelium. As a result, proteins characteristic of the BBB (tight junction proteins and efflux transporters), which are present in the nasal passages, may not be fully functional during the maturation of neurons. The nasal barrier to the central nervous system (CNS) could be considered ‘“leaky”’ because of neurons constant turnover [8].
Related Knowledge Centers
- Bipolar Neuron
- Dendrite
- Gene Expression
- Mucus
- Olfactory Receptor
- Olfactory System
- Sensory Neuron
- Cilium
- Olfactory Epithelium
- G Protein-Coupled Receptor