Endocrine Abstracts

Several hormones, including cortisol, have a circadian rhythm in plasma and saliva. Salivary cortisol is now extensively used for screening and following patients with various conditions where the regulation of hypothalamo-pituitary–adrenal axis is abnormal, for example in major depression where salivary cortisol levels show a disruption or loss of the circadian rhythm.

Annexin 1 is a glucocorticoid-induced protein, which is responsible for mediating several anti-inflammatory actions of glucocorticoids as well as being involved in glucocorticoid negative feedback inhibition. We have previously demonstrated that annexin 1 is present is produced by the submandibular salivary gland and is present in human saliva. We also presented pilot data from six control subjects demonstrating a positive correlation with salivary cortisol, suggesting that cortisol may be regulating salivary annexin 1.

Our objectives were to i) to determine whether it has a diurnal rhythm in secretion which correlates with salivary cortisol and ii) determine if salivary annexin 1 has an awakening response.

We sampled the salivary of 23 healthy subjects at i) time of waking (Time 0), ii) 30 min after waking (30 min) and iii) immediately before sleep (Bed) and measured annexin 1 using an in-house sandwich ELISA and cortisol by commercial EIA (Salimetrics, UK).

Salivary cortisol values demonstrated a significant increase between waking (0.326±0.0436 μg/dl) and 30 min (0.591±0.0645 μg/dl) indicating an awakening response. The confirmation of a diurnal rhythm in cortisol release was determined by a significant decrease in salivary cortisol at the ‘Bed’ sample (0.0521±0.00678 μg/dl) compared to ‘Waking’ sample P<0.05. Salivary annexin 1 levels in the same set of subjects also demonstrated a diurnal rhythm with waking levels measuring 51.63±11.04 ng/ml falling to 15.16±2.94 ng/ml before sleep P<0.05. However, an awakening response was not evident in salivary annexin 1, as mean levels measured 42.32±11.14 ng/ml 30 min post awakening. This suggests that salivary annexin 1 possesses a diurnal rhythm, which correlates positively with cortisol over 24 h. However, the awakening response observed with cortisol is not reflected in levels of salivary annexin 1 possibly due to a lag time between between cortisol and annexin1 secretion from the salivary glands.

We are currently exploring the physiological significance of salivary annexin 1 in the oral cavity and suspect that annexin 1 fulfils a local anti-inflammatory role.