Accumulation of protoporphyrin-IX in rat Leydig cells following induction by 5-aminolevulinic acid and tramadol.

Objectives: This study aimed to monitor the accumulation of endogenous protoporphyrin-IX (PpIX) in rat Leydig cells (R(2)C) under the effect of 5-aminolevulinic acid (ALA) and various concentrations of tramadol, an analgesic drug.

Background Data: Pain during photodynamic treatment with ALA is one of the adverse effects of this new treatment to eradicate tumor cells. ALA is utilized in photodynamic diagnosis and therapy (PDT) as a compound capable of augmenting the intracellular pool of PpIX, which exhibits properties of a photosensitizer.

Methods: Cellular content of PpIX was determined following incubation of the cells for 1 and 2 h in culture medium that contained ALA and different concentrations of tramadol. The amount of PpIX was determined using fluorescent technique under a confocal microscope (laser wavelength 458 nm and filter LP 585 nm), and evaluated using CytFlu 1.2 software.

Results: After 1 h of incubation, no significant alterations were noted in the cellular PpIX concentration. However, 2 h of incubation resulted in a significant increase (p < 0.05) in PpIX fluorescence inside the cells, when the medium contained ALA and tramadol in concentrations ranging from 1-2 mg/1 mL.

Conclusions: The results suggested that in R(2)C cells, exogenous ALA and tramadol induced protoporphyrin accumulation. This information is useful for two reasons. First, it may help to diminish pain after ALA-PDT treatment; and second, it allows the use of lower concentrations of ALA during therapy.