Trigeminal and Olfactory Chemosensory Impact of Selected Terpenes

Abstract

COMETTO-MUÑIZ, J. E., W. S. CAIN, M. H. ABRAHAM AND R. KUMARSINGH. Trigeminal and olfactory chemosensory impact of selected terpenes. PHARMACOL BIOCHEM BEHAV. In Experiment 1, four normosmics and four anosmics (3 congenital, 1 idiopathic) provided odor and nasal pungency thresholds, respectively, for the following terpenes: ∆ 3 -carene, p-cymene, linalool, 1,8-cineole, and geraniol, plus the structurally-related compound cumene. Additionally, all subjects provided nasal localization (i.e., right/left) and eye irritation thresholds. Trigeminally-mediated thresholds (i.e., nasal pungency, nasal localization, and eye irritation) lay about three orders of magnitude above odor thresholds -which ranged between 0.1 and 1.7 ppm. The results implied uniform chemesthetic sensitivity across tasks and sites of impact. In Experiment 2, normosmics and anosmics provided odor and nasal pungency thresholds, respectively, for three pairs of isomeric terpenes: α-and γ-terpinene, α-and ß-pinene, and R(+)-and S(-)-limonene.Odor thresholds ranged between 1.4 and 19 ppm -that is, about an order of magnitude higher than those of the previous terpenes -with no substantial differences between odor thresholds of members of a pair. Regarding chemesthetic impact, only α-terpinene evoked nasal pungency. The overall outcome suggests comparable trigeminal chemosensitivity between nose and eyes and between normosmics and anosmics, as shown before for homologous n-alcohols. It also lends support to a previously-derived solvation model of the chemesthetic potency of airborne substances, and indicates the likely importance of certain molecular-size restrictions for effective trigeminal impact.

Chemesthesis from volatile organic compounds: Psychophysical and neural responses

“…Despite the relative absence of psychometric functions for chemesthesis, there do exist numerous chemesthetic thresholds, i.e., single values on such functions [2,3,[17][18][19][20][21][22]. Thresholds gathered by uniform methodology for more than 40…”

An assessment of air quality reflecting the chemosensory irritation impact of mixtures of volatile organic compounds

“…(4) for VOCs that act through specific effects VOCs that act through physical effects, and so we then added VOCs that act specifically and for which ODT values were available (Devos et al, 1990;Nagata, 2003;Cometto-Muñiz and Cain, 1990, 1994Cometto-Muñiz et al, 1998aCometto-Muñiz and Abraham, 2008a, 2008c, 2009a, 2009b, 2010bHellman and Small, 1974;Rodriguez et al, 2011;Czerny et al, 2011). We also included VOCs that act specifically, and had been studied in the mouse assay (Alarie et al, 1995(Alarie et al, , 1996(Alarie et al, , 1998Schaper 1993).…”

“…We intend to pursue this in the future. Devos et al, 1990 3.868 Mouse test, Alarie et al, 1995Alarie et al, , 1996Alarie et al, , 1998Schaper, 1993 0.469 Inhalation anesthesia, Abraham et al, 2008 6.730 Tadpole narcosis, Bowen et al, 2006 8.616 Inhalation convulsions, Abraham and Acree, 2009 7.040 Draize eye test, Abraham et al, 2003 0.526 Inhalation anesthesia, Davies et al, 1974Davies et al, , 1976 4.746 a Cometto-Muñiz and Cain, 1990Cain, , 1991Cain, , 1993Cain, , 1994Cometto-Muñiz et al, 1998a Cometto-Muñiz and Abraham, 2008aAbraham, , 2008cAbraham, , 2009aAbraham, , 2009bAbraham, , 2010aAbraham, , 2010b The probability that a given air sample containing a number of VOCs could elicit sensory irritation, denoted as Qmix, can then be calculated from the response addition expression, Eq. (6), where the letters a, b. c. … represent different VOCs.…”

Trigeminal Chemesthesis

“…A number of physicochemical properties change orderly and systematically along homologous chemical series. These observations prompted a series of investigations that, using carbon chain length as a practical unit of chemical change, measured nasal pungency thresholds in anosmics and odor detection thresholds in normosmics (i.e., subjects with normal olfaction) towards selected members of homologous alcohols (Cometto-Muñiz and Cain, 1990), acetate esters (Cometto-Muñiz and Cain, 1991), 2-ketones and secondary and tertiary alcohols and acetates (Cometto-Muñiz andCain, 1993), n-alkylbenzenes (Cometto-Muñiz andCain, 1994), aliphatic aldehydes and carboxylic acids (Cometto-Muñiz et al, 1998a), and terpenes (Cometto-Muñiz et al, 1998b). They all employed a uniform methodology that included delivery of vapors via squeeze bottles, a two-alternative forced-choice procedure against blanks (mineral oil), an ascending concentration approach, a fixedcriterion of five correct choices in a row, and measurement of headspace vapor concentration in the bottles via gas chromatography (Cometto-Muñiz and Cain, 1990).…”

“…Some studies have measured nasal localization thresholds in normosmics and in anosmics for selected homologous n-alcohols, terpenes and cumene, employing a "squeeze-bottle" delivery system, an ascending concentration approach, and quantification of vapor concentrations using gas chromatography (Cometto-Muñiz and Cain, 1998;Cometto-Muñiz et al, 1998b). Their outcome suggested slightly lower NLTs for normosmics but the difference failed to achieve statistical significance.…”