The Psychiatrist : Clinical and Therapeutic Journal
Open Access

Schizophrenia, bipolar disorder, and major depressive disorder typically present complicated clinical cases that necessitate extensive medication regimens.Psychotropic polypharmacy treatment may be required in some of these instances [1].Despite its potential to provide significant benefits, polypharmacy has the unfortunate potential to increase a patient's risk of metabolic syndrome and other side effects [2].

Numerous psychotropic polypharmacy combinations have sterol biosynthesis inhibition as a side effect [3].Taking an antidepressant like trazodone (TRZ) and an antipsychotic like aripiprazole (ARI) together is one of the most common combinations of psychotropic drugs.TRZ is an antagonist of 5-HT2A receptors and has a specific effect on neuronal serotonin reuptake.TRZ also has antagonistic effects on 5-HT2B, 5-HT2C, and adrenergic alpha-1 receptors as well as partial agonism at 5-HT1A receptors [4].The antipsychotic quinolinone ARI, on the other hand, is an antagonist of the 5HT-2aA receptor and a partial agonist of the D2 and 5HT1aA receptors [5].It has a moderate affinity for alpha-1 adrenergic and H1 receptors, but a high affinity for D2, D3, 5-HT-1aA, and 5-HT2aA receptors [6].

In addition, it has been demonstrated in a variety of developmental in vitro and in vivo models as well as human biomaterials that ARI and TRZ increase 7-DHC in the central nervous system (CNS). However, it is unknown how ARI and TRZ affect adult peripheral organs during treatment.ARI and TRZ prevent sterol biosynthesis by inhibiting the activity of the enzyme 7-dehydrocholesterol reductase (DHCR7), which also prevents the conversion of 7-dehydrodesmosterol (7-DHD) to desmosterol (DES) and 7-dehydrocholesterol (7-DHC) to cholesterol. The inhibition of DHCR7 ultimately results in two primary effects:7- DHC is the most oxidizable lipid that has been discovered, being 200 times more oxidizable than cholesterol and ten times more oxidizable than arachidonic acid [7]. DES levels have decreased significantly, while 7-DHC levels have increased dramatically.The highly reactive autoxidation sterols known as 7-DHC derived oxysterols are produced as a result of its spontaneous peroxidation, which has a propagation rate constant of 2160.7-DHC.These reactive electrophiles have the potential to influence cell viability, differentiation, and growth due to their bioactive effects and derived from 7-DHC [8].

Cellular homeostasis and structural integrity are dependent on cholesterol biosynthesis, which occurs in all cell types.We investigated the effects of ARI, TRZ, and ARI + TRZ polypharmacy on the postlanosterol peripheral sterol biosynthesis in three cell lines (Neuro2a, HepG2, and human dermal fibroblasts) and an adult mouse model because the effects of ARI and TRZ utilizations across various tissue types are currently poorly understood.The study's layout [9].

For the in vitro treatment, male C57Bl/6J mice (000664) that were three months old were purchased from The Jackson Laboratories [10]. The human dose of TRZ (Desyrel) is 150 mg per day, which can be increased by 50 mg per day up to a maximum of 400 mg per day.In Comparative Medicine at the University of Nebraska Medical Center (UNMC), Omaha, NE, USA, mice were housed in standard ventilated mouse cages with ad libitum access to food (Teklad LM-485 Mouse/ Rat Sterilizable Diet 7012) and water. As a sleep aid, TRZ is frequently prescribed at a starting dose of 50 mg per day.This calculation yields a daily dose of 0.83 mg/kg for a human body mass of 50 mg/60 kg.The human dose (mg/kg) and the Km ratio (12.3) = 10 are used to calculate the animal equivalent dose (AED) in mg/kg. We used a low dose of 10 mg/kg for the experimental treatment of mice.We decided to treat mice with 2.5 mg/kg of ARI (Abilify), which is equivalent to a human ARI dose of 10–15 mg/day, based on the same calculations and literature data.For humans, daily doses ranging from 2 mg to 30 mg are the most common.Except for the control group, which had only eight animals, each of the 35 mice used in our study had nine animals.Every day at 8 a.m., the drug or vehicle was given intraperitoneally.Throughout the experiment, the treatment had no effect on the animals' body mass. The Guide for the Humane Use and Care of Laboratory Animals was followed in all procedures.The UNMC Institutional Animal Care and Use Committee approved the use of mice in this study [11].

Dissection of the tissue and preparing it for sterol analysis Overdose of isoflurane (Forane® isofluranum, produced by Abbott Laboratories LTD;)was used to give the mice anesthesia.Seven organs were dissected in Lake Bluff, Illinois, USA, four to six hours after the last treatment:liver, kidney, spleen, pancreas, heart, lung, and adrenal gland.The spleen's immune function, the liver, pancreas, and kidney's involvement in the metabolic syndrome, the stress response, and the adrenal gland's steroid hormone synthesis were all examined.For serum collection, blood was collected, centrifuged, and all samples were frozen and stored at 80 °C. All tissues were frozen using prechilled methyl-butane [12].

LC-MS/MS Sterol Measurements

The frozen samples were sonicated in a PBS buffer that had been pre-chilled and contained triphenylphosphine (PPh3) and butylated hydroxytoluene (BHT).The first set of aliquots for sterol measurements consisted of 10 L, or 150–250 g of protein [13].For the second set of aliquots for protein measurements, we used 20 L of the same sample solution and diluted it 10 and 20 times to measure protein concentration.The third set of aliquots consisted of 100 milliliters of the starting sample, or approximately 1.5–2.5 milligrams of tissue, for the drug level measurements. The protein was measured using the Pierce BCA assay.After normalizing to protein measurements, sterol levels were expressed as nmol/mg protein.The third set of homogenized tissue aliquots were used for drug measurements.Serum sterol levels were expressed in nmol/mL, and the observed effects were largely dose-dependent. The dose responses are shown for each drug concentration that was tested.Up to a concentration of 100 nM, both drugs and their combined treatment resulted in a synergistic increase in 7-DHC in Neuro2a cells—up to 250-fold for ARI (500 nM), 220-fold for TRZ (500 nM), and 284-fold for ARI+TRZ (500 + 500 nM). We found that Neuro2a cultures showed the greatest increases in 7-DHC when compared to controls treated with vehicle [14].The synergistic effect of 7-DHC increase was present in HepG2 cells even at the highest drug treatment concentrations.7-DHC increased by 42, 62, and 77 folds, respectively, for ARI (100 nM), TRZ (500 nM), and ARI+TRZ (100 + 500 nM), in human fibroblasts at all concentrations tested. It reached a 5-fold increase for ARI (100 nM), a 74-fold increase for TRZ (500 nM), and an 81-fold increase for ARI+TRZ (100 + 500 nCHOL levels decreased significantly only in treated human fibroblasts, and these results persisted across all three treatments and concentrations. The short duration of treatment under in vitro conditions and the low cholesterol turnover rate may account for the absence of a similar effect on CHOL in HepG2 and Neuro 2A cells.LAN concentrations were unaffected by either treatment.These results indicate that the synergistic or summative effects of ARI + TRZ polypharmacy in vitro primarily affect 7-DHC levels [15].

Discussion

Due to the complexity of patients' symptoms, their inability to respond to treatment, or their symptom resistance, psychiatric therapies frequently involve the simultaneous administration of multiple psychotropic medications.Many side effects are reported when two or more psychotropic medications are used to treat up to 30% of psychiatric patients.The majority of these studies, regrettably, were unable to investigate the underlying molecular mechanisms that led to the negative effects.

The molecular mechanisms related to their primary effect, which is achieved by altering the activity of membrane-embedded proteins in the brain like transporters and receptors, are responsible for the majority of the side effects of antipsychotic polypharmacy treatments. According to our investigation, essentially, a portion of the ARITRZ polypharmacy secondary effects can be explained in a different way:their modulating effect on the biosynthesis of sterols by reducing the DHCR7 enzyme's activity.7-DHC-derived oxysterols like DHCEO are produced when DCHR7 inhibition causes 7-DHC to spontaneously peroxide. These biologically active 7-DHC-derived compounds have the potential to influence cell growth and viability.

The fact that ARI and TRZ inhibit DHCR7 in all body tissues and that the elevation of 7-DHC appears to be common to each organ we investigated is particularly noteworthy.We hypothesize that their potential effects on the body may not be dependent on their binding to membrane proteins because all of the peripheral organs we examined responded by inhibiting sterol biosynthesis.ARI is a partial agonist of dopamine D2 receptors, whereas TRZ works through a multitude of receptors and transporters (such as serotonin, histamine, adrenalin/ noradrenalin). However, it is impossible to rule out the possibility that this mechanism is responsible for the effects that inhibit sterol biosynthesis because many of these receptors are located at the periphery. Therefore, depletion of cholesterol, altered endocytosis, and receptor trafficking

Our findings raise a significant question, regardless of the specific mechanism of action:In order to confidently respond to this question, we must first compile a list of prescription medications whose side effects raise 7-DHC and attempt to avoid using both at the same time, particularly in patients with the DHCR7+/- genotype, who already have an elevated 7-DHC at baseline.However, based on the data that are currently available, we suggest that clinical side effects may be related to how well the heart muscle functions when 7-DHC elevating beta-blockers and psychotropic medications are used concurrently. Additionally, organ-specific side effects may be affected by the precise prescription polypharmacy combination, which is largely determined by the medication's intended organ.

Due to the fact that there is a uniform response to ARI and TRZ that inhibits sterol biosynthesis at the periphery, the question of whether the sharp rise in 7-DHC levels ultimately has unfavorable effects on the operation of all somatic organ systems arises.We are unable to provide a definitive response to this question at this time;In the subsequent studies, additional research is required.We hypothesize that the 7-DHC elevation we observed might be a contributing mechanism to this undesirable clinical outcome, given that psychiatric patients taking multiple psychotropic medications frequently develop distinct metabolic disturbances.

The acute stress response and dysregulation of cholesterol synthesis are linked, as is cholesterol-induced apoptosis of beta cells, also known as proximal tubules.In addition, some studies have found a connection between dysregulation of cholesterol synthesis and cholesterol-induced beta apoptosis, also known as the acute stress response of proximal tubules. It is crucial to take into account the possibility that ARI and TRZ directly affect how cholesterol is broken down by macrophages, causing metabolic syndrome and mild inflammation. Systemic changes that cause a vicious cycle that eventually leads to metabolic syndrome cannot be ruled out due to the interconnectedness of glucose and cholesterol metabolisms and the cholesterol imbalance that has been observed in all of the organs.As suggested by us, chronic ARI and TRZ users should be monitored for the onset of non-alcoholic liver steatosis, dyslipidemia, low-grade inflammation, muscle insulin resistance, and changes in the stress response. It should be emphasized here that the spleen had the greatest increase in 7-DHC.

Conclusions

In conclusion, in all of the somatic tissues that we examined, either as a mono- or polypharmacy, ARI and TRZ significantly inhibit sterol biosynthesis or result in an increase in 7-DHC levels and a decrease in DES. They may not be able to do this by binding to the receptor; rather, they may be able to do this by reducing the activity of the DHCR7 enzyme. Both of these effects can be seen across all of the somatic tissues that we investigated. This disruption in sterol biosynthesis may impede the growth and development of multiple organ systems, necessitating additional research.

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