Somatostatin binding sites in human and monkey brain: localization and characterization

Area of Science:

• Neuroscience
• Endocrinology
• Pharmacology

Background:

• Somatostatin is a neuropeptide with diverse physiological roles.
• Understanding somatostatin receptor distribution is crucial for neurological and endocrine research.

Purpose of the Study:

• To localize and characterize somatostatin binding sites in the human and monkey brain.
• To investigate the correlation between somatostatin receptor binding and somatostatin-like immunoreactivity (SLI).
• To assess the stability of somatostatin receptors and their pharmacological properties.

Main Methods:

• Utilized a radioiodinated analogue of somatostatin 28, 125I [Leu8,D-Trp22,Tyr25] SS-28, for binding studies.
• Quantified receptor binding in various brain regions of human and monkey subjects.
• Performed pharmacologic characterization using somatostatin analogues in human cortex.

Main Results:

• High-affinity somatostatin binding sites were identified, predominantly in the cerebral cortex, with lower levels in hippocampus, striatum, amygdala, hypothalamus, and brainstem.
• A correlation was observed between somatostatin receptor binding and SLI concentrations in the human brain.
• Receptor binding remained stable for up to 24 hours under simulated autopsy conditions, with no correlation to postmortem interval.
• Pharmacologic characterization revealed a link between receptor binding inhibition and growth hormone secretion inhibition by somatostatin analogues.

Conclusions:

• A specific, membrane-associated somatostatin receptor is present in both monkey and human brains.
• This receptor system plays a role in regulating hormone secretion.
• Further study of somatostatin receptor binding in neurodegenerative diseases like Alzheimer's and Huntington's may enhance understanding of these conditions.