Chronic verapamil modifies striatal and frontal cortex dopamine levels

Verapamil and Alzheimer's Disease: Past, Present, and Future

Verapamil is a phenylalkylamine class calcium channel blocker that for half a century has been used for the treatment of cardiovascular diseases. Nowadays, verapamil is also considered as a drug option for the treatment of several neurological and psychiatric disorders, such as cluster headache, bipolar disorders, epilepsy, and neurodegenerative diseases. Here, we review insights into the potential preventive and therapeutic role of verapamil on Alzheimer’s disease (AD) based on limited experimental and clinical data. Pharmacological studies have shown that verapamil has a wide therapeutic spectrum, including antihypertensive, anti-inflammatory, and antioxidative effects, regulation of the blood-brain barrier function, due to its effect on P-glycoprotein, as well as adjustment of cellular calcium homeostasis, which may result in the delay of AD onset or ameliorate the symptoms of patients. However, the majority of the AD individuals are on polypharmacotherapy, and the interactions between verapamil and other drugs need to be considered. Therefore, for an appropriate and successful AD treatment, a personalized approach is more than necessary. A well-known narrow pharmacological window of verapamil efficacy may hinder this approach. It is therefore important to note that the verapamil efficacy may be conditioned by different factors. The onset, grade, and brain distribution of AD pathological hallmarks, the time-sequential appearances of AD-related cognitive and behavioral dysfunction, the chronobiologic and gender impact on calcium homeostasis and AD pathogenesis may somehow be influencing that success. In the future, such insights will be crucial for testing the validity of verapamil treatment on animal models of AD and clinical approaches.

Verapamil Blocks Scopolamine Enhancement Effect on Memory Consolidation in Passive Avoidance Task in Rats

Our recent data have indicated that scopolamine, a non-selective muscarinic receptor antagonist, improves memory consolidation, in a passive avoidance task, tested in rats. It has been found that verapamil, a phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, inhibits [3H] N-methyl scopolamine binding to M1 muscarinic receptors. However, there are no data about the effect of verapamil on memory consolidation in the passive avoidance task, in rats. The purpose of the present study was to examine the effects of verapamil (0.5, 1.0, 2.5, 5.0, 10, or 20 mg/kg i.p.) as well as the interaction between scopolamine and verapamil on memory consolidation in the step-through passive avoidance task, in Wistar rats. Our results showed that verapamil (1.0 and 2.5 mg/kg) administered immediately after the acquisition task significantly increased the latency of the passive avoidance response, on the 48 h retested trial, improving memory consolidation. On the other hand, verapamil in a dose of 5 mg/kg, that per se does not affect memory consolidation, significantly reversed the memory consolidation improvement induced by scopolamine (1 mg/kg, i.p., administered immediately after verapamil treatment) but did not change the passive avoidance response in rats treated by an ineffective dose of scopolamine (30 mg/kg). In conclusion, the present data suggest that (1) the post-training administration of verapamil, dose-dependently, improves the passive avoidance response; (2) verapamil, in ineffective dose, abolished the improvement of memory consolidation effect of scopolamine; and (3) exists interaction between cholinergic muscarinic receptors and calcium homeostasis-related mechanisms in the consolidation of emotional memory.

Alpha1,6-fucosyltransferase-deficient mice exhibit multiple behavioral abnormalities associated with a schizophrenia-like phenotype: importance of the balance between the dopamine and serotonin systems

Previously, we reported that α1,6-fucosyltransferase (Fut8)-deficient (Fut8(-/-)) mice exhibit emphysema-like changes in the lung and severe growth retardation due to dysregulation of TGF-β1 and EGF receptors and to abnormal integrin activation, respectively. To study the role of α1,6-fucosylation in brain tissue where Fut8 is highly expressed, we examined Fut8(-/-) mice using a combination of neurological and behavioral tests. Fut8(-/-) mice exhibited multiple behavioral abnormalities consistent with a schizophrenia-like phenotype. Fut8(-/-) mice displayed increased locomotion compared with wild-type (Fut8(+/+)) and heterozygous (Fut8(+/-)) mice. In particular, Fut8(-/-) mice showed strenuous hopping behavior in a novel environment. Working memory performance was impaired in Fut8(-/-) mice as evidenced by the Y-maze tests. Furthermore, Fut8(-/-) mice showed prepulse inhibition (PPI) deficiency. Intriguingly, although there was no significant difference between Fut8(+/+) and Fut8(+/-) mice in the PPI test under normal conditions, Fut8(+/-) mice showed impaired PPI after exposure to a restraint stress. This result suggests that reduced expression of Fut8 is a plausible cause of schizophrenia and related disorders. The levels of serotonin metabolites were significantly decreased in both the striatum and nucleus accumbens of the Fut8(-/-) mice. Likewise, treatment with haloperidol, which is an antipsychotic drug that antagonizes dopaminergic and serotonergic receptors, significantly reduced hopping behaviors. The present study is the first to clearly demonstrate that α1,6-fucosylation plays an important role in the brain, and that it might be related to schizophrenia-like behaviors. Thus, the results of the present study provide new insights into the underlying mechanisms responsible for schizophrenia and related disorders.

Verapamil treatment for women with bipolar disorder

BACKGROUND

Additional pharmacological treatments are needed for patients with bipolar disorder. We describe our experience with verapamil in an inclusive, sequential series of outpatient women (some pregnant) with bipolar disorder.

METHODS

All women who were prescribed verapamil for bipolar disorder (n = 37) were included. We used the criterion of 50% reduction in scores on the Mania Rating Scale or the Hamilton Rating Scale for Depression to define response for women who were treated for an acute episode of bipolar hypomania/mania or depression, respectively. For euthymic women who chose verapamil maintenance treatment, we evaluated whether they met criteria for a recurrent episode during therapy.

RESULTS

Treatment for acute episodes was initiated in 28 women. Of women with depression and mania, 39% and 100% responded, respectively. Seven of the nine patients (77%) with mixed states responded: all seven improved to response criterion on the mania scale, and two responded on the depression scales as well. Six of eight patients who received continuation therapy remained well.

CONCLUSIONS

These data provide evidence that verapamil is effective for mania. The response rate for mania compares favorably to that for other mood stabilizers. After decades of case reports and underpowered clinical trials, we must definitively study verapamil for efficacy and gender specificity in bipolar disorder.

Differential effects of treatment with typical and atypical antipsychotic drugs on adenylyl cyclase and G proteins

We examined the effects of chronic in vivo antipsychotic drug treatments on G protein function and regulation. Mice were treated with typical antipsychotic haloperidol (6 mg/kg per day) and atypical agent olanzapine (20 mg/kg per day) for 14 days via mini-osmotic pumps. G protein-activated adenylyl cyclase activity in brain tissues was measured in the presence of guanine nucleotide analogue guanosine-5'-O(3-thiotriphosphate) tetralithium salt, or GTPgammaS. In frontal cortex, haloperidol treatment produced 21% increases in the GTPgammaS -mediated adenylyl cyclase Emax value (vs. vehicle controls) while olanzapine produced 20% reductions in this value (vs. controls); these effects were significant. In striatum, olanzapine treatment produced significant 31 and 27% decreases in Emax values compared with vehicle and haloperidol treatment, respectively. Chronic haloperidol treatment produced significant 24% reductions in the immunoreactivity of cortical, but not striatal, Gialpha1,2 subunits. There were no effects of chronic olanzapine treatment on G(i)alpha1,2 levels and no effects of either antipsychotic on G(s)alpha, levels. Chronic haloperidol and olanzapine treatments differentially regulate G protein-mediated adenylyl cyclase responses in brain regions possibly relating to their unique effects on G protein-coupled receptors.