Background: Lipocalin-2 (Lcn2) was initially identified as a protein secreted from human neutrophils. It has been implicated in many functions as inflammation, cell survival, innate immunity and biology of the genitourinary system as a developmental and a protective factor. The effect of testosterone on the circulating lipocalin-2 level in adult male rats is still unknown.
Objective: To explore the effect of testosterone on serum lipocalin-2 levels in orchidectomized adult male albino rats.
Material and Methods: The present study was conducted on 32 adult male albino Wistar rats divided into 4 equal groups: group (I): Sham operated control group; group (II): Orchidectomized group;  group (III): Orchidectomized with subcutaneous physiologic testosterone replacement therapy; group (IV): Orchidectomized with subcutaneous supra-physiologic dose of testosterone.
Results: In group (II) and group (III), serum lipocalin-2 level significantly decreased compared to control group. In group (IV), there was further significant reduction in serum lipocalin-2 when compared with control group, group II and group III with a significant negative correlation with serum testosterone level.
Conclusion: Normal physiologic levels of testosterone are needed for normal lipocalin-2 expression. Disturbance of testosterone level (either by decrease or increase) significantly decreased lipocalin-2 level.