Tag Archives: progesterone

Responsiveness to progesterone and potassium channel blockers 4-aminopyridine, tetraethylammonium and free Ca(2+) contentration in spermatozoa of patients with oligozoospermia/leucocytospermia

R. V. Fafula1, G. V. Danylovych2, A. S. Besedina1, O. V. Melnyk1, Z. D. Vorobets1

1Danylo Halytsky Lviv National Medical University, Ukraine;
2Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: roman_fafula@ukr.net

The present study was undertaken to evaluate [Ca2+]i signals that occur in human sperm cells exposed in vitro to three diverse compounds; progesterone, 4-aminopyridine (a highly effective inducer of hyperactivation in human sperm) and tetraethylammonium. The [Ca2+]i reached after the extracellular calcium treatment was always higher in normozoospermic samples pretreated with progesterone than in pathozoospermic samples pretreated with progesterone. There were no changes in calcium signal in spermatozoa pretreated with progesterone from patients with oligozoospermia and leucocytospermia compared to control samples (without progesterone). [Ca2+]i was always higher in pathozoospermic samples without 4-aminopyridine and always lower in pathozoospermic samples with 4-aminopyridine compared to these values in normozoospermic men. The 2 mM extracellular calcium administration to spermatozoa pretreated with tetraethylammonium did not result in a detectable increase in [Ca2+]i in normo- and pathozoospermic samples. The mechanisms of progesterone-dependent activation of the Ca2+-entry and the functioning of the voltage gated Ca2+-channels of plasmalemma are disturbed in pathologies – there was no increase in the Ca2+ level in the conditions of K+-depolarization (in the presence of inhibitors of K+-channels).

Biological effects of thyroid hormones

T. S. Saatov, A. A. Abduavaliev

Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent;
e-mail: t.saatov@yandex.ru

The article presents the findings from the study on multifunctional effects of thyroid hormones in relation to normal and malignantly transformed tissues and cells. Both “rapid” and «slow» effects of thyroid hormones including calorigenic effects and effects over adenylate cyclase – cAMP system have been described.  Thyroxin (Т4) has been established capable to inhibit proliferation and to induce apoptosis of cells carrying Т4 receptors on their membranes as well as to change course of metabolic processes under its effect. Spectrum of Т4 targets is quite broad to include not only cells of hormone-producing organs, to name those of the breast and the colon, but also other types of cells to name melanin-containing ones; Т4 effects resulting in reconstruction of presentation of regulatory proteins on the cell membrane surface to ultimately activate the process of cell apoptosis.  Our findings help determine alternative paths for hormonal regulation of cell proliferation and apoptosis of cells of hormone-dependent tumors, breast cancer, in particular, upon impossibility to regulate the processes by conventional methods. This facilitates understanding mechanisms for activation of signal system of the breast cancer’s cells by hormones upon changes in expression of receptors on the cells’ surface, making possible development of novel strategy for replacement therapy of hormone-dependent tumors upon low efficacy of drug therapy.