Multiple forms of immunoreactive renin in human pituitary tissue

Area of Science:

• Endocrinology
• Biochemistry
• Human Physiology

Background:

• Renin, an enzyme crucial for blood pressure regulation, is primarily known to be produced by the kidneys.
• Previous studies have suggested the presence of renin or renin-like activity in various extra-renal tissues, including the brain.

Purpose of the Study:

• To investigate the presence and biochemical characteristics of immunoreactive renin in human pituitary tissues.
• To determine if the identified renin activity is specific and to characterize its properties.

Main Methods:

• Immunohistochemical demonstration of renin in postmortem human pituitary tissues.
• Assay of specific immunoreactive renin activity and total renin-like activity.
• Biochemical characterization of pituitary renin using techniques such as molecular mass determination, concanavalin A-Sepharose binding, and isoelectric focusing.

Main Results:

• Immunoreactive renin was detected in human pituitary tissues from subjects with various diseases.
• Specific immunoreactive renin activity constituted the majority (mean, 83%) of the total renin-like activity, ruling out significant non-specific protease actions.
• Biochemical analysis of three pituitary specimens revealed variations in molecular mass (45 K, 42 K, 37 K) and isoelectric points (pI 4.72–5.44), indicating microheterogeneity.

Conclusions:

• The findings provide evidence for the presence of specific renin within the human pituitary gland.
• The observed microheterogeneity suggests that pituitary renin exists in multiple forms, potentially with different functions or origins.