The effect of ionising radiation on testosterone binding globulin characteristics: Correction of the protein' parameters by lipid polyene complexes of fungus Laetiporus sulfureus

Abstract

Purpose: The aims of this work were: (i) To compare the effects of ionising radiation (IR) on testosterone binding globulin (TeBG) characteristics (serum concentration, cooperativity of androgen binding and affinity for hormone) in divergent mammalian species; (ii) to couple radiation effects with probable TeBG-parameter changes; and (iii) to investigate the prevention of these changes by fungal preparations (in particular – by lipid polyene complexes of Laetiporus sulphureus).

Materials and methods: Characteristics of TeBG were investigated in microaliquots of rat and human serum samples using [³H]-5α-dihydrotestosterone ([³H]-DHT) radioligand assays after in vivo exposures to IR (external γ-sources, incorporation of ¹³¹I-, ¹³⁷Cs-radionuclides) at experimental and post-Chernobyl radioecological conditions (doses 0.25–2.2 Gy).

Results: Species-specific changes of TeBG parameters were found depending on the type of IR, dose and time after irradiation. Specifically children living in radionuclide contaminated regions (near Chernobyl) were found to have a decrease of positive cooperativity for the TeBG-androgen binding, a drop of TeBG levels, and a decline in hormone affinity. Screening of natural substances (from phanerogams and fungi) detected that lipid polyene complexes of the basidiomycete L. sulphureus allowed recovery of the standard features of TeBG.

Conclusions: IR induced a depletion of TeBG from blood simultaneously with species-specific changes of TeBG, which depend on the type of radiation, the dose of radiation (from 0.25 up to 2.2 Gy), and the time after radiation. The Hill coefficient of TeBG (indicating the degree of molecular cooperativity when hormone binding) appeared to be the most radiosensitive marker of the glycoprotein activity because of it is inversely to radiation dose. There are pharmacological possibilities to restore IR-induced “declines” of TeBG's affinity and cooperativity for androgen ligand binding.

Keywords:

• low-dose ionising radiation
• testosterone binding globulin
• lipid polyene complex of Laetiporus sulphureus

Acknowledgements

The authors are grateful to Doctor of Medical Sciences, Professor, and Academician E.F. Konoplya for valuable comments during manuscript preparation, and to other staff members of the Institute of Radiobiology, Belarus National Academy of Science for technical assistance during this study. Financial support was provided by Belarus State Program (Reg. No. 2002956) funding and by Grant No. 99P-216 from the Belarus Republic Foundation for Basic Research.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.