Plasma guanosine 3',5'-monophosphate responses to methacholine and epinephrine in humans

The effect of ECT on plasma cyclic nucleotides: a simulated ECT controlled study in melancholic patients

Concentrations of cAMP and cGMP in plasma were measured in 20 drug-free melancholic patients during a simulated electroconvulsive treatment (SECT) and a bilateral ECT session. Blood samples were taken every 15 min beginning 15 min before and ending 60 min after the SECT or the ECT. Two-way ANOVA and paired t-test demonstrated a significant and greater fall in cAMP over time following SECT. ECT induced a marginal increase (P less than 0.05) at 45 min postictally. It is postulated that ECT causes an increase in cAMP levels which is masked by the decrease observed during SECT, caused presumably by the anaesthetic medication. The plasma cGMP levels were increased gradually and significantly after SECT and the same rise was observed during ECT. These effects are discussed in relation to changes in adrenergic-cholinergic activities induced by the medication and the electrical stimulus.

Prospective strategies for cholinergic interventions in Alzheimer's disease

The cholinergic hypothesis of memory dysfunction has guided most of the recent proposals for treating the primary symptoms of AD. The efficacy of these treatments has been severely limited. This review examines two major lines of evidence which suggest that the cholinergic hypothesis may have to be expanded and revised. The cholinergic hypothesis focuses on pre-synaptic defects. It assumes cholinoceptive neurons would function normally with adequate stimulation. Evidence is not sufficient to support this assumption. In addition, dissociations have been demonstrated between muscarinic receptor number and functional response of cholinoceptive neurons. Various measures are proposed to investigate the functional integrity of muscarinic receptors in AD patients. AD often has been characterized as a disorder produced by generalized cholinergic hypoactivity. Evidence for cortisol hypersecretion, abnormal dexamethasone suppression, and the occurrence of depressive symptoms, motoric dysfunction and sleep abnormalities in AD patients is more consistent with regional cholinergic hyperactivity than generalized hypoactivity. Resolution of these discrepancies could shed new light on the pathophysiology and treatment strategies for AD. Cholinoceptive neurons could be hypersensitive, subsensitive or have unaltered responsivity. These options would have very different treatment implications. New developments in outcome assessment which are capable of discriminating varieties of differential response to treatment can spur treatment development and improve quality of care for patients with complex disorders such as AD.

Effects of acute cannabis use on urinary neurotransmitter metabolites and cyclic nucleotides in man

The noradrenaline, dopamine and serotonin metabolites methoxyhydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), as well as the cyclic nucleotides c-AMP and c-GMP were estimated in urine samples of five normal volunteers. Ten control samples and two samples after cannabis use were analyzed for each volunteer. Cannabis use caused significant decreases in MHPG and c-AMP, and increases in HVA, while 5-HIAA and c-GMP excretion remained unchanged. The results indicate that cannabis use interferes with catecholaminergic mechanisms in man, decreasing the noradrenaline and increasing dopamine turnover, probably through action on presynaptic receptors.

Plasma guanosine 3',5'-monophosphate responses to the cold pressor test in patients with vibration disease

Plasma cyclic guanosine 3',5'-monophosphate (cyclic GMP) levels were determined during the cold pressor test (CPT) in 10 normal volunteers and 39 patients with vibration disease. The CPT caused no significant increase in plasma cyclic GMP in the controls. There was a sharp rise in plasma cyclic GMP during and after the CPT in patients with vibration disease. This increase was suppressed by simultaneous injection of phentolamine or atropine. In patients who had been treated with kallidinogenase or nicametate citrate for 3-6 months, the CPT caused no significant increase in plasma cyclic GMP. In 1 patient the plasma cyclic GMP was suppressed by dihydroergotamine. From these findings it is very likely that cholinergic or alpha-adrenergic receptor responses are enhanced in patients with vibration disease.