Effect of Chromium Picolinate on Modified Forced Swimming Test in Diabetic Rats: Involvement of Serotonergic Pathways and Potassium Channels

Joint replenishment of zinc and folic acid enhances the anti-depressive effect of paroxetine via increasing serum calcium and copper and decreasing serum arsenic

Insufficient zinc and folic acid levels are associated with depression and poor response to antidepressants. This study aimed to investigate the influences of combined zinc and folic acid replenishment on the anti-depressive effect of paroxetine. Male rats were randomly divided into five groups: control (C), model (M), paroxetine (MP), zinc + folic acid (MZnF), and zinc + folic acid + paroxetine (MZnFP) groups. Rats were exposed to mild unpredictable stress for 3 weeks as a depression model. The combinations of drug and supplements were applied via daily gavage for 4 weeks. The open field test was conducted to observe behavioral changes. A chemiluminescence method was used to detect folacin, and inductively coupled plasma mass spectrometry was used to detect serum elements. Supplementation of zinc and folic acid significantly improved behavior responses to paroxetine, including movement speed, total distance, and central zone frequency. In addition, higher calcium and copper levels and a lower arsenic level were found in the serum of the MZnFP group. Thus, supplementation of zinc and folacin can enhance the anti-depressive effect of paroxetine, and the mechanism is potentially related to the improved levels of calcium and copper and a reduced level of arsenic.

Analysis of Density Changes of Selected Brain Receptors After a 14-Day Supply of Chromium(III) and Evaluation of Chromium(III) Affinity to Selected Receptors and Transporters

Chromium(III) is one of the most controversial biometals. Although, it is no longer on the list of minerals necessary for the proper functioning of the human body, and its pharmacological effect is still under discussion. One of the purposes of Cr(III) administration is to use it in patients with mood disorders and it is strictly related to its pharmacological, not dietary effect. This is because its high doses are necessary to obtain the results and additionally, no deficiencies in human population have been noted. In this study, the affinity of chromium(III) to selected receptors and transporters in the rat brain was evaluated, and the effect of the 14-day administration of this metal was assessed on the density of selected receptors. All analyses were performed in vitro using radioligand binding assays, and the results indicated lack of affinity to β₁ and α₁ receptors and serotonin transporter (SERT), furthermore very weak affinity to the 5-HT_1A receptor (30% inhibition at 10^-4 and 10^-5 M). Analysis of the α₁ and β₁ adrenergic receptor density indicated lack of any adaptive effects after 14 days of Cr(III) administration through intraperitoneal injections (doses 6 and 12 mg/kg). The antidepressant activity of chromium(III) indicated in clinical trials concerned patients with atypical, seasonal, or dystonic symptoms. This effect, as it seems based on the presented results, does not depend on direct affinity to serotonin receptors and transporter nor is the result of adaptive changes in the adrenoreceptor system.

The Possibilities of Using Chromium Salts as an Agent Supporting Treatment of Polycystic Ovary Syndrome

The polycystic ovary syndrome (PCOS) is the most frequent endocrinopathy in women in reproductive age with the so far undetermined causes of development. In the etiopathogenesis of PCOS, the role of insulin resistance is emphasised, which was an indication for the attempts at using chromium III salts (Cr) in augmenting pharmacotherapy applied in patients. The analysis of the usefulness and efficacy of this approach was the direct goal of this thesis. Animal tests confirmed the efficacy of chromium in maintaining the appropriate level of glycaemia and insulinaemia, normalisation of plasma concentrations of microelements and also a correlation between the Cr level, insulin and dehydroepiandrosterone (DHEA) was found. A decrease in the expression of 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase was identified in adipose tissue. Clinical studies, although sparse, show that the supplementation with chromium can improve BMI and the parameters evaluating the control of glycaemia and increase the chances for ovulation and regular menstruation. However, the small number and a variability in study protocols makes comparing them very difficult. A completely new subject that has not been yet studied is the possibility of using chromium in levelling mood disorders in patients with PCOS. Currently, there are still no sufficient proofs for introducing chromium as a standard in treating and preventing insulin resistance in patients with PCOS. However, this direction remains open, and treating insulin resistance is an important challenge in clinical practice.

Chromium picolinate reduces morphine-dependence in rats, while increasing brain serotonin levels

Chromium is an essential trace element with anti-diabetic and anti-depressant effect; the latter is considered related to chromium properties of increasing brain serotonin. Cr³⁺ salts were shown to improve some forced swimming-parameters and to induce rewarding effects, which are additive to those of morphine, but Cr effect on addictive processes has not been tested.

AIM

The present study aimed to assess chromium picolinate (CrPi) influence on morphine-dependence in rats.

MATHERIAL AND METHODS

We used five groups of 10 rats. Groups 1 and 2 (controls) received saline, respectively CrPi, 0.01 mg/kg/day, for 10 days. In groups 3, 4 and 5 dependence was induced with progressively-increased morphine doses (from 5 - day 1-90 mg/kg/day - day 10, s.c.). Group 3 received only morphine, while groups 4 and 5 received CrPi, i.p., 10 and respectively 5 μg/kg/day, during the 10 days of dependence induction. On day 11, groups 3, 4, and 5 were administered 90 mg/kg morphine, and, 2 h later, all rats received naloxone, 2 mg/kg s.c., to precipitate withdrawal. We compared withdrawal intensity in group 3 vs. groups 4 and 5, assessing both individual symptoms and Gellert-Holtzman global withdrawal score. Upon rats sacrifice at the end of the experiments, brain serotonin (5HT) in certain areas and serum Cr were assessed.

RESULTS

Some withdrawal signs were unequally influenced by CrPi: compulsive mastication was reduced by both CrPi doses (p < 0.05), while teeth chattering and grooming were significantly reduced only by the higher dose (p < 0.05). Withdrawal score was reduced by both CrPi doses: from 132.4 ± 9.87 - group 3 to 122.2 ± 6.47 - group 4 (p < 0.01 vs. group 3) and 124.1 ± 8.41 - group 5 (p < 0.05 vs. group 3). CrPi reduction of withdrawal is accompanied by increased brain 5 H T, mainly in the prefrontal cortex (646.3 ± 8.51 - group 3 vs. 661.5 ± 14.63 - group 4, p < 0.01 and 660.7 ± 14.01 pg/mg tissue - group 5, p < 0.05 vs. group 3). CrPi also increases brain 5 H T in non-dependent rats (prefrontal cortex: 541.6 ± 31.80, group 1 and 565.5 ± 16. 46 pg/mg tissue, group 2, p < 0.05). Administration of CrPi determined a dose-dependent increase of serum Cr.

CONCLUSIONS

Our study evidenced a slight, but significant reduction of morphine dependence in rats induced by chromium picolinate, accompanied by increased brain serotonin. This might be considered a supplementary evidence for chromium anti-depressant effect and its serotonin-mediated mechanisms.

Study of the Role of Dopamine Receptors in Streptozotocin-Induced Depressive-Like Behavior Using the Forced Swim Test Model

Background:

Diabetes is one of the most common endocrine diseases characterized by hyperglycemia. It is caused by an absolute or relative insulin deficiency or an insulin function deficiency. It is one of the major risk factors of depression, with the rate of depression in diabetic patients amounting to as high as 30%. This study examined the role of dopamine receptors in streptozotocin (STZ)-induced depressive-like behavior using the forced swim test (FST).

Materials and Methods:

This study was performed on 56 Wistar male rats. STZ at doses of 30 and 60 mg/kg body weight was administered via intraperitoneal (IP) route to induce diabetes and depression in rats. Thereafter, by using halobenzazepine (SCH23390) (D1 dopamine receptor antagonist) and sulpiride (D2 receptor dopamine receptor antagonist), the role of dopamine receptors in STZ-induced depression was studied. The one-way analysis of variance technique, Tukey’s range test, and t-test were used to analyze the data. The P-value less than 0.05 was regarded as statistically significant.

Results:

Our study showed that STZ at doses of 30 and 60 mg/kg, two weeks after injection, caused prolonged immobility in FST, indicating depressive-like behavior (P<0.05 and P<0.01, respectively). SCH23390 (0.001 mg/mL/kg) and sulpiride (0.1 mg/mL/kg) did not change the variables of depression in animals that received STZ (at doses of 30 and 60 mg/mL/kg) two weeks before (P>0.05).

Conclusion:

According to our study, STZ has a depressive-like behavior two weeks after injection, and dopamine receptors do not play a role in depression associated with STZ use.

Anxiety and memory deficits induced by tannery effluent in C57BL/6J female mice

This study aimed to evaluate the behavior of female C57Bl/6J mice exposed to tannery effluents diluted in drinking water. Female mice were divided into a control group, in which the animals received only drinking water, and experimental groups, which received raw tannery effluent in 7.5 and 15 % concentrations diluted in water (period of 60 days). In the last experimental week, the mice (in diestrus phase) were subjected to different behavioral tests: elevated plus-maze, open-field test, forced swim test, and object recognition test. Our data demonstrated that exposure to tannery effluent increased the anxiety index of animals and decreased the locomotion ratio in the central quadrants/total, indicating an increase in anxiety-like behavior. Regarding the forced swim test, we did not observe changes in the evaluated behaviors. There were no statistically significant differences in the recognition index of the novel and familiar object in the groups exposed to tannery effluent compared with the control group, indicating a possible influence of the constituents of tannery effluent on cognition. Thus, our findings support the hypothesis that effluents, containing neurotoxic substances, could cause behavioral disruptions in female C57Bl/6J mice.

An enzyme in the kynurenine pathway that governs vulnerability to suicidal behavior by regulating excitotoxicity and neuroinflammation

Emerging evidence suggests that inflammation has a key role in depression and suicidal behavior. The kynurenine pathway is involved in neuroinflammation and regulates glutamate neurotransmission. In the cerebrospinal fluid (CSF) of suicidal patients, levels of inflammatory cytokines and the kynurenine metabolite quinolinic acid (QUIN), an N-methyl-d-aspartate receptor agonist, are increased. The enzyme amino-β-carboxymuconate-semialdehyde-decarboxylase (ACMSD) limits QUIN formation by competitive production of the neuroprotective metabolite picolinic acid (PIC). Therefore, decreased ACMSD activity can lead to excess QUIN. We tested the hypothesis that deficient ACMSD activity underlies suicidal behavior. We measured PIC and QUIN in CSF and plasma samples from 137 patients exhibiting suicidal behavior and 71 healthy controls. We used DSM-IV and the Montgomery-Åsberg Depression Rating Scale and Suicide Assessment Scale to assess behavioral changes. Finally, we genotyped ACMSD tag single-nucleotide polymorphisms (SNPs) in 77 of the patients and 150 population-based controls. Suicide attempters had reduced PIC and a decreased PIC/QUIN ratio in both CSF (P<0.001) and blood (P=0.001 and P<0.01, respectively). The reductions of PIC in CSF were sustained over 2 years after the suicide attempt based on repeated measures. The minor C allele of the ACMSD SNP rs2121337 was more prevalent in suicide attempters and associated with increased CSF QUIN. Taken together, our data suggest that increased QUIN levels may result from reduced activity of ACMSD in suicidal subjects. We conclude that measures of kynurenine metabolites can be explored as biomarkers of suicide risk, and that ACMSD is a potential therapeutic target in suicidal behavior.

Evaluation of the Reproductive Toxicity, Glycometabolism, Glycometabolism-Related Enzyme Levels and Lipid Metabolism of Chromium Malate Supplementation in Sprague-Dawley Rats

Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the reproductive toxicity of chromium malate in Sprague-Dawley rats and then inspected the effect of chromium malate on glycometabolism, glycometabolism-related enzymes, and lipid metabolism. The results showed that no pathological, toxic feces and urine changes were observed in clinical signs of parental and fetal rats in chromium malate groups. The fasting blood glucose, serum insulin, insulin resistance index, C-peptide, hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels of chromium malate groups have no significant change compared with control group and chromium picolinate group. The serum and organ contents of Cr in chromium malate groups have no significant change when compared with control group. No measurable damage on liver, brain, kidney, and testis/uterus of chromium malate groups was found. No significant change in body mass, absolute and relative organ weights, and hematological and biochemical changes of rats were observed compared with the control and chromium picolinate groups. The results indicated that supplements with chromium malate does not cause obvious damage and has no obvious effect on glycometabolism, glycometabolism-related enzyme, and lipid metabolism on female and male rats. The results of this study suggested that chromium malate is safe for human consumption and has the potential for application as a functional food ingredient and dietary supplement.

Possible involvement of corticosterone and serotonin in antidepressant and antianxiety effects of chromium picolinate in chronic unpredictable mild stress induced depression and anxiety in rats

In the present study, we investigated the effects of chromium picolinate (CrP) on behavioural and biochemical parameters in chronic unpredictable mild stress (CUMS) induced depression and anxiety in rats. The normal and stressed male Swiss albino rats were administered CrP (8 and 16μg/mL in drinking water), they received stressors for seven days (each day one stressor) and this cycle was repeated three times for 21 days. On 22nd day, behaviour assessments followed by biochemical estimations were conducted. The results showed that treatment of CrP produced significant antidepressant effect, which has been evidenced by decrease in immobility time in modified forced swimming test (FST) in chronic unpredictable mild stress (CUMS) induced depression in rats. In elevated plus maze (EPM), CrP (16μg/mL) showed significant reduction in time spent in open arm. CrP (8μg/mL and 16μg/mL) also showed significant decrease in number of entries in open arm that shows antianxiety effect of CrP in CUMS rats. It was also found that CrP (8 and 16μg/mL) significantly increased 5-HT concentration in the discrete regions of brain (cortex and cerebellum). On the other hand, the plasma corticosterone level was significantly decreased with CrP (16μg/mL). The results suggested that increase in the concentration of 5-HT and decrease in plasma corticosterone levels could be responsible for improvement in symptoms of depression and anxiety in CUMS induced depression and anxiety in rats.

Is chromium pharmacologically relevant?

Recent research, combined with reanalysis of previous results, has revealed that chromium can no longer be considered an essential trace element. Clinical studies are ambiguous at best as to whether Cr has a pharmacological effect in humans. Observed effects of Cr on rodent models of insulin resistance and diabetes are best interpreted in terms of a pharmacological role for Cr. Studies on the effects of Cr on rat models of diabetes are reviewed herein and suggest Cr increases insulin sensitivity in peripheral tissues of the rodent models. The lack of effects in human studies may stem from humans receiving a comparably smaller dose than the rodent models. However, given the different responses to Cr in the rodent models, humans could potentially have different responses to Cr.

Essential elements in depression and anxiety. Part I

Essential elements are very important for the proper functioning of the human body. They are required for fundamental life processes such as cell division and differentiation and protein synthesis. Thus a deficiency of these essential elements is associated with an enormous health risk that can ultimately lead to death. In recent years, studies have provided valuable information on the involvement of essential elements in psychiatric disorders, in particular depression and anxiety. There is strong evidence indicating that deficiency of essential elements can lead to the development of depressive and/or anxiogenic behaviour and supplementation can enhance therapeutic effect of antidepressants and anxiolytics. This review presents the most important results from preclinical and clinical studies showing involvement of essential elements such as zinc, magnesium, lithium, iron, calcium and chromium in depression and anxiety. From these studies it is evident that different types of depression and anxiety respond to treatment at different receptors indicating that the underlying mechanisms are slightly different. Furthermore, administration of low dose antidepressants supplemented with an element is effective and can reduce unwanted side effects in different types of depression/anxiety.

Chromium picolinate modulates serotonergic properties and carbohydrate metabolism in a rat model of diabetes

Chromium picolinate (CrPic) has shown both antidepressant and antidiabetic properties. In this study, the effects of CrPic on serotonergic properties and carbohydrate metabolism in diabetic rats were evaluated. Sixty male Sprague-Dawley rats were divided into four groups. (1) The control group received only standard diet (8 % fat). (2) The CrPic group was fed standard diet and CrPic (80 μg CrPic per kilogram body mass (b.m.)/day), for 10 weeks (microgram/kilogram b.m./day). (3) The HFD/STZ group fed a high-fat diet (HFD, 40 % fat) for 2 weeks and then received streptozotocin (STZ, 40 mg/kg, i.p.) (i.v.) HFD-STZ-CrPic group treated as the previous group and then were administered CrPic. CrPic administration to HFD/STZ-treated rats increased brain chromium levels and improved all measurements of carbohydrate metabolism and serotonergic properties (P<0.001). CrPic also significantly increased levels of insulin, tryptophan, and serotonin (P<0.001) in the serum and brain, and decreased cortisol levels in the serum (P<0.01). Except chromium levels, no significant effect of CrPic supplementation was detected on the overall measured parameters in the control group. CrPic administration was well tolerated without any adverse events. The results support the use of CrPic supplementation which improves serotonergic properties of brain in diabetes.

The effects of chromium complex and level on glucose metabolism and memory acquisition in rats fed high-fat diet

Conditions in which glucose metabolism is impaired due to insulin resistance are associated with memory impairment. It was hypothesized that supplemental chromium (Cr) may alleviate insulin resistance in type 2 diabetes and consequently improve memory acquisition, depending upon its source and level. In a complete randomized design experiment, male Wistar rats (n=60; weighing 200-220 g) were fed either normal (8%, normal diet (ND)) or high-fat (40%, high-fat diet (HFD)) diet and supplemented with Cr as either chromium-glycinate (CrGly) or chromium-acetate (CrAc) at doses of 0, 40, or 80 μg/kg body weight (BW) via drinking water from 8 to 20 weeks of age. Feeding HFD induced type 2 diabetes, as reflected by greater glucose/insulin ratio (2.98 vs. 2.74) comparing to feeding ND. Moreover, HFD rats had greater BW (314 vs. 279 g) and less serum (53 vs. 68 μg/L) and brain (14 vs. 24 ng/g) Cr concentrations than ND rats. High-fat diet caused a 32% reduction in expressions of glucose transporters 1 and 3 (GLUTs) in brain tissue and a 27% reduction in mean percentage time spent in the target quadrant and a 38% increase in spatial memory acquisition phase (SMAP) compared with ND. Compared with supplemental Cr as CrAc, CrGly was more effective to ameliorate response variables (i.e., restoration of tissue Cr concentration, enhancement of cerebral GLUTs expressions, and reduction of the glucose/insulin ratio and SMAP) in a dose-response manner, especially in rats fed HFD. Supplemental Cr as CrGly may have therapeutic potential to enhance insulin action and alleviate memory acquisition in a dose-dependent manner, through restoring tissue Cr reserve and enhancing cerebral GLUTs expressions.

Second-tier natural antidepressants: review and critique

The use of Complementary and Alternative Medicine (CAM) for physical and mental problems has increased significantly in the US over the past two decades, and depression is one of the leading indications for the use of CAM. This article reviews some of the lesser-known natural products with potential psychiatric applications that are starting to emerge with some scientific and clinical evidence and may constitute a next wave of natural antidepressants: Rhodiola rosea, chromium, 5-Hydroxytryptophan (5-HTP) and inositol. Background information, efficacy data, proposed mechanisms of action, recommended doses, side effects, and precautions are reviewed. We found some encouraging data for the use of these natural products in specific populations of depressed patients. R. rosea is an adaptogen plant that can be especially helpful in treating asthenic or lethargic depression, and may be combined with conventional antidepressants to alleviate some of their common side effects. Chromium has a beneficial effect on eating-related atypical symptoms of depression, and may be a valuable agent in treating atypical depression and seasonal affective disorder. Inositol may be useful in the treatment of bipolar depression when combined with mood stabilizers. Evidence for the clinical efficacy of 5-HTP is also promising but still preliminary. Although more well-designed and larger controlled studies are needed before any substantive conclusions can be drawn, the available evidence is compelling and these natural products deserve further investigation as a possibly significant addition to the antidepressant armamentarium.

Effects of pre- and postnatal exposure to chromium picolinate or picolinic acid on neurological development in CD-1 mice

Chromium picolinate, Cr(pic)3, a popular dietary supplement marketed as an aid in fat loss and lean muscle gain, has also been suggested as a therapy for women with gestational diabetes. The current study investigated the effects of maternal exposure to Cr(pic)3 and picolinic acid during gestation and lactation on neurological development of the offspring. Mated female CD-1 mice were fed diets from implantation through weaning that were either untreated or that contained Cr(pic)3 (200 mg kg(-1) day(-1)) or picolinic acid (174 mg kg(-1) day(-1)). A comprehensive battery of postnatal tests was administered, including a modified Fox battery, straight-channel swim, open-field activity, and odor-discrimination tests. Pups exposed to picolinic acid tended to weigh less than either control or Cr(pic)3-exposed pups, although the differences were not significant. Offspring of picolinic acid-treated dams also appeared to display impaired learning ability, diminished olfactory orientation ability, and decreased forelimb grip strength, although the differences among the treatment groups were not significant. The results indicate that there were no significant effects on the offspring with regard to neurological development from supplementation of the dams with either Cr(pic)3 or picolinic acid.

Effect of chronic chromium picolinate in animal models of anxiety and memory

Diabetes mellitus is associated with certain neurological problems such as depression, anxiety, memory impairment, etc. As chromium picolinate (CrP), a widely used trace element is shown to have beneficial effects in diabetes and depression, we investigated its effects on elevated plus maze and spontaneous alternation behavior paradigm as a measure of anxiety and memory, respectively. CrP (8 microg/mL in drinking water) significantly increased percentage preference to open arm in elevated plus maze in diabetic and normal rats. However, no significant changes were observed in percentage alternation after CrP chronic treatment. The possible anxiolytic effect of CrP might be related to its effect on serotonergic transmission.

Effect of chromium on carbohydrate and lipid metabolism in a rat model of type 2 diabetes mellitus: the fat-fed, streptozotocin-treated rat

Chromium supplements are widely used as an alternative remedy for type 2 diabetes mellitus (T2DM). In vitro study findings show that chromium picolinate (CrPic) may improve insulin sensitivity by enhancing intracellular insulin receptor. In this study, we evaluated the metabolic effects of CrPic in a rat model of T2DM. Male Sprague-Dawley rats (n = 45, 8 weeks old) were divided into 3 groups. The controls (group I) received a standard diet (12% of calories as fat); group II received a high-fat diet (HFD; 40% of calories as fat) for 2 weeks and then were intraperitoneally injected with streptozotocin (STZ, 40 mg/kg; HFD/STZ) on day 14; group III rats were given group II diets with the addition of 80 microg CrPic per kilogram body weight per day. The addition of CrPic in the group III treatment lowered glucose by an average of 63% (P < .001), total cholesterol by 9.7% (P < .001), and triglycerides by 6.6% (P < .001) compared with group II treatment. Compared with group II, CrPic treatment also lowered free fatty acid levels by 24% (P < .001), blood urea by 33% (P < .05), and creatinine level by 25% (P < .01), and reduced the severity of glomerular sclerosis (P < .0001). Histopathologic findings suggest that the CrPic-treated group had normal renal tubular appearance compared with the HFD/STZ-treated group. Normal appearance of hepatocytes was observed in the CrPic-treated group. These results showed that CrPic has marked beneficial effects against microvascular complications. In conclusion, HFD/STZ rats provide a novel animal model for T2DM. Further treatment with CrPic for 10 weeks significantly ameliorated changes in metabolic risk factors including favorable changes in histopathology of the liver, kidney, and pancreas, suggesting its potential role in the management of diabetes.

Managing psychiatric disorders with antidiabetic agents: translational research and treatment opportunities

The objective of this paper is to synthesise extant studies describing the neurotherapeutic effects of antidiabetic agents in neuropsychiatric disorders. The authors conducted a MedLine search of all English-language articles published between 1966 and March 2006. The search terms were the nonproprietary names of established and putative antidiabetic agents (e.g., insulin, insulin secretagogues and sensitisers) cross-referenced with the individual names of Diagnostic and Statistical Manual of Mental Disorders (DSM)-III-R/IV/-TR-defined mood, psychotic, anxiety and dementing disorders. The search was augmented with a manual review of article reference lists. Contemporary models of disease pathophysiology in major depressive disorder, bipolar disorder and several dementing disorders (e.g., Alzheimer's disease) emphasise alterations in cellular plasticity and cytoarchitecture, with associated regional abnormalities in neuronal and glial density and morphology. Antidiabetic treatments (e.g., thiazolidinediones) may be capable of attenuating this pathological process via disparate mechanisms (e.g., neuroprotective, neurotrophic, anti-inflammatory). Enhanced insulin signalling with antidiabetic treatments may preserve and/or augment cognitive function in several neuropsychiatric disorders. Antidiabetic treatments, which maintain euglycaemia, hold promise as potent and clinically significant therapeutic interventions for several neuropsychiatric disorders.