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Immunocytochemical localization of epidermal growth factor in mouse kidney
Abstract:
Epidermal growth factor (EGF) was originally isolated from mouse submandibular glands (SMG). However, SMG removal failed to lower circulating EGF, and large amounts of EGF have been found in mouse urine. In addition, the presence of pre-pro-EGF mRNA in mouse kidney has recently been reported by others. Kidneys may therefore represent an alternate source of EGF. In the present study, we investigated the immunocytochemical localization of EGF in mouse kidney. Male and female adult Swiss Webster mice were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative, the kidneys were frozen, and serial sections were obtained. Rabbit EGF antiserum was used for the primary incubation and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. EGF was immunolocalized in the apical portion of the cells lining the thick ascending limb of Henle (TALH) and the distal convoluted tubule (DCT). The macula densa, in contrast, lacked EGF immunoreactivity. No sex differences were observed in the distribution pattern or intensity of immunostaining. Infusion of EGF into sheep renal artery has been reported to induce changes in urine flow and ionic composition. Immunolocalization of EGF in the TALH and DCT documented here supports a regulatory role for EGF in the function of the mouse distal nephron.
Insights
Epidermal growth factor (EGF) is found in mouse kidneys, specifically in the thick ascending limb of Henle and distal convoluted tubule. This localization suggests EGF plays a role in regulating distal nephron function.
Area of Science:
- Nephrology
- Molecular Biology
- Immunohistochemistry
Background:
- Epidermal growth factor (EGF) was initially isolated from mouse submandibular glands (SMG).
- Circulating EGF levels were not affected by SMG removal, and significant EGF amounts were detected in mouse urine.
- Previous studies reported pre-pro-EGF mRNA in mouse kidneys, suggesting the kidney as an alternative EGF source.
Purpose of the Study:
- To investigate the immunocytochemical localization of EGF within the mouse kidney.
- To determine if the kidney is a significant source of EGF.
- To explore the potential role of EGF in distal nephron regulation.
Main Methods:
- Adult male and female Swiss Webster mice were used.
- Kidneys were fixed, frozen, and sectioned.
- Immunostaining utilized rabbit EGF antiserum and the avidin-biotin complex immunoperoxidase method.
Main Results:
- EGF was localized to the apical portion of cells in the thick ascending limb of Henle (TALH) and the distal convoluted tubule (DCT).
- The macula densa showed no EGF immunoreactivity.
- No observed sex differences in EGF distribution or staining intensity.
Conclusions:
- The immunolocalization of EGF in the TALH and DCT supports its regulatory role in mouse distal nephron function.
- The mouse kidney is identified as a significant source of EGF.
- These findings contribute to understanding EGF's physiological functions in the kidney.