Prolactin secretion in response to haloperidol challenge in delusional (psychotic) and non-delusional depression

The Association Between Psychotropic Drug Use and Fertility Problems Among Male Subjects

Mental disorders affect a high percentage of the general population and are associated with a significant burden. One major component of treatment for mental illnesses is pharmacotherapy. Various psychotropic medications are used in the treatment of psychiatric disorders and these are often associated with a plethora of side effects. The many side effects of psychotropic drugs can severely impair patients' quality of life and decrease their adherence to treatment. Among the relatively neglected and less-studied potential side effects of psychotropic drugs are impairment of sperm parameters and fertility problems among male patients. This article summarizes the data with regard to the effects of 6 widely used psychotropic drugs-lithium, valproate, haloperidol, olanzapine, imipramine, and fluoxetine-on sexual function and sperm parameters in male subjects. In general, the reviewed data suggest that these medications can be associated with sexual function problems and negative effects on sperm parameters among male subjects. It is important to note that most of the data are based on preclinical studies and nonrandomized clinical trials with relatively small sample sizes, so that it is not possible to draw unequivocal conclusions with regard to the clinical relevance of the findings. Prospective, randomized clinical trials are necessary to elucidate the effects of psychotropic drugs on men's sperm parameters and fertility indices per se.

Sigma receptors [σRs]: biology in normal and diseased states

This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ₁R) and sigma receptor two (σ₂R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ₁Rs are intracellular receptors acting as chaperone proteins that modulate Ca²⁺ signaling through the IP₃ receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ₁R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K⁺ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ₁R modulation of Ca²⁺ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ₁Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them.

Antipsychotics: impact on prolactin levels

Hyperprolactinaemia has been associated with a variety of side effects including amenorrhoea, galactorrhoea, sexual dysfunction, breast engorgement and osteoporosis. Since the mid-1970s, the impact of antipsychotics on human prolactin (hPrl) levels has been investigated. Baseline levels of hPrl were found to be similar in healthy controls and patients who were diagnosed as having schizophrenia. Short-term acute studies done after single parenteral or oral doses of phenothiazines found rapid two- to tenfold increases in hPrl. Similar increases were found in longer term studies that reported increases of three times in both men and women after 3 days that doubled again after several weeks of treatment. A study of longer term injectable fluphenazine enanthate found that elevation induced by a single injection lasted up to 28 days. The same results with significant increases have been reported with the butyrophenone, haloperidol. Substantial increases are found after single injections (up to nine times) and after weeks of treatment (up to three times sustained). Thus, early literature believed that there might be an association between these induced changes and response to therapy. However, prolactin is secreted by the anterior pituitary and is under inhibitory control of dopamine released from the tuberoinfundibular neurones. Thus, increases in prolactin are due to antipsychotic impact on tuberoinfundibular tract, one of four dopamine-related tracts. With the application of clozapine and other atypical antipsychotics, it was found that medications can successfully treat psychosis without increasing hPrl. In fact, early single-dose trails found clozapine to reduce hPrl by 16%. Later studies replicated this result and also found that up to 6 weeks of administration led to reductions in hPrl of up to 80%. Risperidone, however, has been found to persistently elevate hPrl in studies, despite its impact on other receptor sites. Olanzapine, quetiapine and ziprasidone have all been found to have little effect or produce decreases in hPrl. Most recently, aripiprazole, in early studies, appears to produce significant reductions in hPrl while maintaining therapeutic efficacy for psychosis.