Prolonged histamine deficiency in histidine decarboxylase gene knockout mice affects Leydig cell function

Area of Science:

• Reproductive biology
• Endocrinology
• Molecular biology

Background:

• Leydig cells are crucial for testosterone synthesis in the testis.
• The role of histamine (HA) in regulating Leydig cell physiology is not well understood.
• Histidine decarboxylase (HDC) is the enzyme responsible for HA synthesis.

Purpose of the Study:

• To investigate the role of histamine in Leydig cell function.
• To determine the effect of histamine deficiency on testosterone production and response to hCG.
• To explore the expression of histamine receptors in Leydig cells.

Main Methods:

• Primary Leydig cells were isolated from wild-type (WT) and HDC gene knockout (HDC KO) mice.
• Cells were cultured and treated with or without human chorionic gonadotropin (hCG).
• Testosterone production and gene expression levels (Cyp11a1, H1, H2 receptors) were analyzed.

Main Results:

• HDC KO Leydig cells exhibited reduced basal and hCG-stimulated testosterone production compared to WT cells.
• Altered expression of the P450scc gene (Cyp11a1) was observed in HDC KO cells.
• HDC KO cells showed no increase in histamine H1 and H2 receptor gene expression upon hCG stimulation, unlike WT cells.

Conclusions:

• Histamine plays a direct role in modulating Leydig cell function and steroid synthesis.
• Histamine deficiency negatively impacts Leydig cell responsiveness to hCG.
• This study provides the first molecular evidence for histamine H1 and H2 receptor expression in isolated Leydig cells.