Observations on the cyclic nucleotide concentrations in human cerebrospinal fluid

Area of Science:

• Neurochemistry
• Neurology
• Biomarkers

Background:

• Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in cerebrospinal fluid (CSF) and brain tissue are influenced by neurotransmitters.
• Previous research indicates that melanotropic peptides and catecholamines can increase cAMP and cGMP concentrations.

Purpose of the Study:

• To measure cAMP, cGMP, and melanotropic activity in the CSF of normal individuals and patients with neurological diseases.
• To investigate the relationship between these biomarkers and specific neurological conditions, including hydrocephalus and psychomotor development disorders.

Main Methods:

• Measurement of cAMP, cGMP, and melanotropic activity in CSF samples from 136 patients with various neurological conditions and normal controls.
• Analysis of CSF and ventricular fluid samples, correlating nucleotide levels with clinical parameters like ventricular pressure.

Main Results:

• Normal lumbar CSF concentrations: cAMP (21 ± 8 mM), cGMP (2.4 ± 0.5 mM), melanotropic activity (17 ± 6 units/100 ml).
• No significant differences in cAMP, cGMP, or melanotropic activity were found in patients with cerebral atrophy, vascular disease, or uncomplicated brain tumors.
• Nine children with diffuse brain disease causing psychomotor retardation exhibited subnormal cAMP and melanotropic activity levels, which were significantly correlated (r=+0.55).
• Ventricular fluid cGMP levels were significantly elevated in patients with increased intracranial pressure, showing a strong positive correlation with ventricular pressure (r=+0.76).

Conclusions:

• Subnormal cAMP and melanotropic activity may indicate diffuse brain disease in children with psychomotor retardation.
• Elevated ventricular cGMP is a reliable indicator of increased intracranial pressure, regardless of the cause or type of hydrocephalus.