We have previously published that cAMP and cGMP, substances involved with both transduction and maintenance of taste and smell function, were present in human parotid saliva. This work confirmed studies of several earlier investigators.

We have now compared levels of these substances in parotid saliva of normal subjects and of patients with smell loss (hyposmia).

Results indicate that cAMP and cGMP are decreased in patients with hyposmia compared to subjects with normal smell function. This is the first time these results have been demonstrated.

This finding is important since it establishes for the first time that levels of these critical signalling moeities are decreased in patients with hyposmia. This finding is also important since it can serve as a marker to identify patients with hyposmia.

We have previously demonstrated that secretory decreases in some salivary moeities reflect changes in smell function. This is based upon the finding that substances in saliva are in many ways similar to substances in nasal mucus. Thus secretory impairment in cAMP and cGMP in saliva may reflect a similar secretory impairment in nasal mucus.

These results lend support to the hypothesis that impairment of salivary cAMP and cGMP secretion is a major factor in causation of smell loss. These results also support the basis for treatment of patients with both smell loss and decreased saliva cAMP and cGMP secretion with theophylline, a therapy which has been successful in restoring smell function to normal in patients with this combination of pathological findings.

For further information about these problems, see:

1. Henkin, R.I., Velicu, I, Papathanissiu,A. Dichotomous changes in cAMP and cGMP in human parotid saliva after oral theophylline. FASEB J. 17:A1028, 2003.
   
2. Levy, L.M., Henkin, R.I., Hutter, A, Lin, C.S., Schellinger, D. Increased brain activation in response to odors in patients with hyposmia after theophylline treatment demonstrated by fMRI. J. Comp. Asst. Tomog. 22:760-770, 1998.
   
3. Law, J.S., Henkin, R.I. Low parotid saliva calmodulin in patients with taste and smell dysfunction. Biochem. Med. Met. Biol. 36: 118-124, 1986.