Identification of 2 new allergens of Phoenix dactylifera using an immunoproteomics approach.

The date palm (Phoenix dactylifera) has a wide geographical distribution (Middle East, Mediterranean, central Africa, western Asia, Australia, and North America). Pho d 2, the major allergen of date palm pollen was recently identified as a profilin, yet little is known about the nature of the other pollen allergens from this tree. The objective of this study was to characterize clinically significant allergens other than profilins from P. dactylifera pollen using immunoproteomics. In order to reveal the proteins causing the allergy, we used serum from a patient monosensitized to date palm pollen extract who experienced asthma and rhinoconjunctivitis during the palm tree pollen season. The results revealed 2 novel immunoglobulin E-binding proteins not related to the cross-reactive allergen profilin. Individualized allergens of Pdactylifera that cause specific date palm pollen sensitization must be defined to determine the real prevalence of sensitization to this species.

Rat brain opioid peptides-circadian rhythm is under control of melatonin.

Several experiments have revealed an Endogenous Opioid System (EOS)-circadian rhythm. The brain-borne hormone, melatonin (MEL) has been shown to regulate the organism photoperiodic activity and may be implicated in the EOS-circadian rhythm. To explore this hypothesis, we studied the effect of functional pinealectomy on the EOS-circadian rhythm by measuring the immunoreactive content of Met-Enkephalin, Leu-Enkephalin and Synenkephalin in both hypothalamus and hippocampus of the rat brain, using standard radioimmunoassay procedures. Experimental animals exposed to white fluorescent light (WFL) for 15days (<50lux), displayed a disruption of the EOS-circadian rhythm, showing that absence of MEL induced a significant decrease of tissue content of enkephalin peptides at 01:00h during the dark-phase of the 24-h circadian rhythm, when compared to control rats. Functional pinealectomized rats exposed to 4 or 6h period of darkness (used to revert the effects induced by the absence of melatonin) significantly increased the tissue content of ME-IR and LE-IR, when compared to both controls and non-exposed WFL-treated rats. In addition, subcutaneous administration of exogenous melatonin (10, 100, 150, 300, 600microg/kg), in WFL-treated animals produced significant dose-dependent increases of ME-IR in both brain regions tested. Finally, luzindole (melatonin receptor antagonist) administration, was not able to prevent the enkephalin tissue increase, induced with the MEL administration (150microg/kg). This data suggest that MEL not only regulates the EOS-circadian rhythm, but also appears to modulate their synthesis in the rat brain from their respective neurons.