pridopidine and preclamol

The first part of the present review describes the exciting journey of dopamine stabilizers, starting in the early eighties with the development of the partial dopamine agonist (-)-3-PPP of phenylpiperidine structure, via various compounds with aminotetraline structure with preferential autoreceptor antagonist properties, and then back again to phenylpiperidine compounds carrying substituents on the aromatic ring that transformed them from partial dopamine agonists to partial dopamine receptor antagonists, such as OSU6162. OSU6162 was brought to the clinic and has in preliminary trials showed antidyskinetic and antipsychotic efficacy. The second part of this review describes results from a hypoglutamatergia mouse model for cognitive symptoms of schizophrenia, where we have tested traditional neuroleptics, new generation antipsychotics with marked 5-HT2 vs dopamine D2 receptor blockade as well as a dopamine stabilizer belonging to the partial dopamine receptor antagonist category.

Topics: Animals; Antipsychotic Agents; Aripiprazole; Disease Models, Animal; Dopamine; Dopamine Agonists; Dopamine Antagonists; Excitatory Amino Acid Antagonists; Glutamic Acid; Mice; Piperazines; Piperidines; Quinolones; Schizophrenia

The tri-nucleotide repeat expansion underlying Huntington disease (HD) results in corticostriatal synaptic dysfunction and subsequent neurodegeneration of striatal medium spiny neurons (MSNs). HD is a devastating autosomal dominant disease with no disease-modifying treatments. Pridopidine, a postulated "dopamine stabilizer", has been shown to improve motor symptoms in clinical trials of HD. However, the target(s) and mechanism of action of pridopidine remain to be fully elucidated. As binding studies identified sigma-1 receptor (S1R) as a high-affinity receptor for pridopidine, we evaluated the relevance of S1R as a therapeutic target of pridopidine in HD. S1R is an endoplasmic reticulum - (ER) resident transmembrane protein and is regulated by ER calcium homeostasis, which is perturbed in HD. Consistent with ER calcium dysregulation, we observed striatal upregulation of S1R in aged YAC128 transgenic HD mice and HD patients. We previously demonstrated that dendritic MSN spines are lost in aged corticostriatal co-cultures from YAC128 mice. We report here that pridopidine and the chemically similar S1R agonist 3-PPP prevent MSN spine loss in aging YAC128 co-cultures. Spine protection was blocked by neuronal deletion of S1R. Pridopidine treatment suppressed supranormal ER Ca

Topics: Aging; Animals; Calbindins; Calcium; Cations, Divalent; Coculture Techniques; Corpus Striatum; Dendritic Spines; Disease Models, Animal; Endoplasmic Reticulum; Humans; Huntington Disease; Mice; Mice, Transgenic; Neuroprotective Agents; Piperidines; Rats, Inbred SHR; Receptors, sigma; Sigma-1 Receptor; Synapses

Dopaminergic stabilizers may be conceptualized as drugs with normalizing effects on dopamine-mediated behaviours and neurochemical events. (S)-(-)-OSU6162 (OSU6162) and ACR16 are two structurally related compounds ascribed such properties, principally because of their stabilizing effects on motor activity in rodents. Reports in the literature indicate possible partial D2 receptor agonist effects using various in vitro systems. This study aimed to measure D2 receptor antagonist and agonist effects of OSU6162 and ACR16 in vivo. To address this, we have studied the effects of both compounds on prolactin secretion in drug-naive and dopamine-depleted rats; dopamine depletion was induced by pretreatment with reserpine plus α-methyl-DL: -p-tyrosine. We find that OSU6162 and ACR16 both stimulate prolactin secretion in drug-naive rats with OSU6162 being considerably more potent and efficacious. Both compounds show a non-significant trend towards reversal of the increased secretion caused by dopamine depletion, whereas the D2 receptor antagonist haloperidol further increased prolactin secretion. Thus, this study suggests that OSU6162 and ACR16 act as D2 receptor antagonists under normal conditions in vivo, possibly with minor agonist effects in a state of dopamine depletion.

Topics: Animals; Aripiprazole; Dopamine; Dopamine Agonists; Dopamine Antagonists; Dopamine D2 Receptor Antagonists; Haloperidol; Hyperprolactinemia; Lactotrophs; Male; Methyltyrosines; Piperazines; Piperidines; Prolactin; Quinolones; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D2; Reserpine