Studies on cyclic AMP in different compartments of cerebrospinal fluid

CSF concentrations of cAMP and cGMP are lower in patients with Creutzfeldt-Jakob disease but not Parkinson's disease and amyotrophic lateral sclerosis

Background

The cyclic nucleotides cyclic adenosine-3′,5′-monophosphate (cAMP) and cyclic guanosine-3′,5′-monophosphate (cGMP) are important second messengers and are potential biomarkers for Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Creutzfeldt-Jakob disease (CJD).

Methodology/Principal Findings

Here, we investigated by liquid chromatography/tandem mass spectrometry (LC-MS/MS) the cerebrospinal fluid (CSF) concentrations of cAMP and cGMP of 82 patients and evaluated their diagnostic potency as biomarkers. For comparison with a well-accepted biomarker, we measured tau concentrations in CSF of CJD and control patients. CJD patients (n = 15) had lower cAMP (−70%) and cGMP (−55%) concentrations in CSF compared with controls (n = 11). There was no difference in PD, PD dementia (PDD) and ALS cases. Receiver operating characteristic (ROC) curve analyses confirmed cAMP and cGMP as valuable diagnostic markers for CJD indicated by the area under the curve (AUC) of 0.86 (cAMP) and 0.85 (cGMP). We calculated a sensitivity of 100% and specificity of 64% for cAMP and a sensitivity of 67% and specificity of 100% for cGMP. The combination of both nucleotides increased the sensitivity to 80% and specificity to 91% for the term cAMPxcGMP (AUC 0.92) and to 93% and 100% for the ratio tau/cAMP (AUC 0.99).

Conclusions/Significance

We conclude that the CSF determination of cAMP and cGMP may easily be included in the diagnosis of CJD and could be helpful in monitoring disease progression as well as in therapy control.

Selective D1 agonism but not D2 antagonism is reflected in cAMP and cGMP levels in rat CSF

Cyclic adenosine 3'5'-monophosphate (cAMP) and cyclic guanosine 3'5'-monophosphate (cGMP) serve as second messengers in several cellular pathways within the central nervous system. In various neurological and psychiatric disorders with known deficits in neurotransmission function, CSF levels of cAMP and/or cGMP in patients were studied. Very little information is currently available on cAMP and cGMP levels in CSF of animals. Moreover, this is the first study on the effects of pharmacological treatment on cAMP and cGMP levels in rat CSF. Effect of systemic treatment with a D1 receptor agonist SKF82958 and a D2 receptor antagonist haloperidol on cAMP and cGMP levels, as well as baseline cAMP and cGMP levels in CSF of rats was determined. A significantly increased cAMP and cGMP level in cisternal CSF of rats systemically treated with the D1 receptor agonist SKF82958 was observed, while when treated with the D2 antagonist haloperidol, no effect on cAMP and only a slight decrease of cGMP was observed after treatment with the highest dose. Determining cAMP and/or cGMP in CSF of experimental animals can serve as a useful tool to study neural processes affected by disease and treatment.

Cerebrospinal fluid levels of cyclic nucleotides in meningitis and idiopathic polyneuritis

Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) were measured in cerebrospinal fluid (CSF) and plasma from 7 patients with bacterial meningitis, 9 patients with serous meningitis, 5 patients with idiopathic polyneuritis and 15 reference patients. A significantly (P less than 0.01) higher mean concentration of CSF cAMP was found in serous meningitis (33.8 +/- 12.5 nmol/l) compared to the reference group (20.2 +/- 4.0 nmol/l). No significant difference could be observed between the patients with purulent meningitis compared to the reference group. The CSF cAMP concentration (11.0 +/- 2.8 nmol/l) for idiopathic polyneuritis was significantly (P less than 0.01) lower than in the reference group. No difference in CSF levels of cGMP or in the cAMP/cGMP ratios were detected between the groups. Our data suggest that the ratio between cAMP concentrations in CSF and plasma may aid in the differential diagnosis between serous and purulent meningitis.

Hypothalamic-pituitary dopaminergic function in hepatic failure in man

The growth hormone (GH) response to apomorphine HCl (Apo) (0.75 mg sc), a dopamine (DA) receptor agonist, was assessed in healthy chronic alcoholics without cirrhosis (N = 20) and in patients with alcoholic cirrhosis both with (N = 5) and without (N = 14) hepatic encephalopathy (HE). A significant number of cirrhotic patients with (P less than 0.004) and without (P less than 0.002) HE had an impaired GH response (peak increment less than 5 ng/ml) compared with non-cirrhotic individuals. An impaired GH response was independent of the presence of HE. The magnitude of the GH response was unrelated to plasma oestrone, oestradiol, or progesterone concentrations but was significantly correlated with plasma testosterone levels (P less than 0.01). None of the patients with an abnormally low testosterone concentration showed a normal GH response. None of the subjects with HE showed an arousal response to Apo. These results suggest that DA receptor sensitivity is decreased in liver cirrhosis and that this decrease is related to inadequate circulating levels of testosterone. The occurrence of HE is independent of impaired DA function. The present study only evaluates DA function in the hypothalamic-pituitary axis and therefore may not reflect changes in other regions of brain.

Cerebrospinal fluid GABA and cyclic nucleotides in alcoholics with and without seizures

Cerebrospinal fluid levels of gamma-aminobutyric acid (GABA) and cyclic nucleotides were measured in alcoholic and control patients. Alcoholics without seizures had higher GABA levels than either alcoholics with seizures or controls. Levels of cyclic AMP and cyclic GMP in cerebrospinal fluid of controls and alcoholics with and without seizures were not significantly different.

Noradrenergic overactivity in chronic schizophrenia: evidence based on cerebrospinal fluid noradrenaline and cyclic nucleotide concentrations

Concentrations of noradrenaline (NA), homovanillic acid, 5-hydroxyindoleacetic acid and cyclic nucleotides were determined in lumbar cerebrospinal fluid (CSF) from acute and chronic schizophrenics and various groups of psychiatric and non-psychiatric control subjects. Statistically significant increases in NA and cyclic adenosine monophosphate were found in CSF from chronic schizophrenics compared to all other groups. These results were shown by statistical analyses to be unrelated to medication. They may be interpreted as evidence for noradrenergic overactivity as a possible primary abnormality in chronic schizophrenia.

Central nervous system lupus erythematosus: measurement of cerebrospinal fluid cyclic GMP and other clinical markers of disease activity

Cyclic-GMP (C-GMP), a normal constituent of the central nervous system, was found to be present in increased amounts in the cerebrospinal fluid (CSF) of systemic lupus erythematosus (SLE) patients with active neurologic disease. Twenty-four CSF samples from 17 patients with SLE were evaluated for C-GMP concentration by radioimmunoassay. This study extends our initial observations and examines three groups of SLE patients based on their clinical status at the time of each lumbar puncture: those with active neurologic and psychologic abnormalities (group I), active neurologic abnormalities (group II), and psychologic abnormalities without active neurologic involvement (group III). Groups I and II had mean CSF C-GMP values of 3.1 nM +/- 0.64 (SE) and 4.1 nM +/- 0.10 respectively, which were both significantly higher than the mean for group III (1.2 nM +/- 0.43) (P less than 0.05). Other CSF findings did not display this close correlation with activity of neurologic disease. In 4 SLE patients, significantly higher levels of CSF C-GMP were found on serial sampling during times when neurologic abnormalities were active. Thus elevated CSF C-GMP concentration may be a marker of active neurologic disease in SLE.

The effect of L-dopa and propranolol on human CSF cyclic nucleotides

Human CSF cyclic AMP and cyclic GMP have been measured as possible indicators of activity of central neurotransmitter-sensitive adenylate or guanylate cyclase. In an attempt to help to identify the specific neurotransmitter systems of origin of human CSF cyclic AMP and GMP, we studied Parkinson patients with and without L-dopa therapy and schizophrenic patients before and after propranolol therapy. No effect of L-dopa or propranolol was found on CSF cyclic nucleotides. However, Parkinson patients had a 40-50% reduction of CSF cyclic AMP and a 80-90% reduction of CSF cyclic GMP compared with the schizophrenic patients. Implications of this finding are discussed.