Leydig cell–derived heme oxygenase-1 regulates apoptosis of premeiotic germ cells in response to stress
Nobuaki Ozawa, … , Yasunori Yoshimura, Makoto Suematsu
Nobuaki Ozawa, … , Yasunori Yoshimura, Makoto Suematsu
Published February 15, 2002
Citation Information: J Clin Invest. 2002;109(4):457-467. https://doi.org/10.1172/JCI13190.
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Article

Leydig cell–derived heme oxygenase-1 regulates apoptosis of premeiotic germ cells in response to stress

Abstract

Stress-induced downregulation of spermatogenesis remains poorly understood. This study examined the induction of heme oxygenase-1 (HO-1), a carbon monoxide–generating inducible enzyme, in modulation of spermatogenesis. Rats were exposed to cadmium chloride (CdCl2), a stressor causing oligozoospermia, and HO-1–induction was monitored by following HO isozyme expression. CdCl2-treated testes increased HO-1 activity and suppressed microsomal cytochromes P450, which are required for steroidogenesis. CdCl2-elicited HO-1 occurred mostly in Leydig cells and coincided with CO generation, as judged by bilirubin-IXα immunoreactivity. Under these circumstances, germ cells in peripheral regions of seminiferous tubules exhibited apoptosis; laser flow cytometry revealed that these apoptotic cells involve diploid and tetraploid germ cells, suggesting involvement of spermatogonia and primary spermatocytes in CdCl2-elicited apoptosis. Pretreatment with zinc protoporphyrin-IX, an HO inhibitor, but not copper protoporphyrin-IX, which does not block the enzyme, attenuated the CdCl2-induced apoptosis. Such antiapoptotic effects of zinc protoporphyrin-IX were repressed by supplementation of dichloromethane, a CO donor. Upon CdCl2-treatment, both Sertoli cells and the germ cells upregulated Fas ligand; this event was also suppressed by zinc protoporphyrin-IX and restored by dichloromethane. Thus, Leydig cells appear to use HO-1–derived CO to trigger apoptosis of premeiotic germ cells and thereby modulate spermatogenesis under conditions of stress.

Authors

Nobuaki Ozawa, Nobuhito Goda, Nobuya Makino, Tokio Yamaguchi, Yasunori Yoshimura, Makoto Suematsu

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Figure 9

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Overexpression of FasL in testicular diploid cells elicited by CdCl2. (a...
Overexpression of FasL in testicular diploid cells elicited by CdCl2. (a) Western blot analyses in whole testicular lysates using the anti-FasL Ab sc-834. Densitometric analyses indicate relative gray levels versus controls (mean ± SE of four separate experiments). CdCl2 at 20 μmol/kg was administered 12 hours before experiments. *P ≤ 0.05 as compared with the control. (b) Dual-color analyses between DNA contents (PI) and FasL expression (sc-834). (c) Histograms showing alterations in the FasL expression in the diploid cells among groups. A representative set of three experiments was shown. Histograms with gray backgrounds indicate controls stained by rabbit IgG. Note that the CdCl2 exposure markedly upregulates FasL expression, and the event was attenuated by ZnPP and restored by CO donation with dichloromethane (asterisks).