Social distancing and changes in drug use: Results from a cross-sectional study during the COVID-19 pandemic in Brazil

BACKGROUND

The outbreak of coronavirus disease 19 has led to measures of social distancing and quarantine worldwide. This stressful period may lead to psychological problems, including changes in substance use. In addition, sociodemographic factors are linked to changed levels of drug use and abuse observed during the COVID-19 pandemic, which are also associated with increased anxiety, depression, and other disorders. Thus, the aim of the study was to investigate (i) changes in drug use during the COVID-19 pandemic associated with social distancing, and (ii) to verify factors associated with those changes.

METHODS

A web-based cross-sectional observational survey was completed by a self-selected adult general population in Brazil (N = 2,435) during September/October 2020 (first wave) before and throughout the pandemic. Key outcomes: social distancing, self-reported drug use (ASSIST), and emotional states (DASS-21).

RESULTS

High social distancing was associated with fewer chances (prevalence ratio) of increased drug use for alcohol (0.71, CI_95%: 0.64-0.80), tobacco (0.72; CI_95%: 0.60-0.87), cannabis (0.65; CI_95%: 0.55-0.78), and others. Low social distancing presented a higher DASS-21 score for anxiety (P = 0.017). Concerning covariates analysis by a general linear model, men (alcohol: 1. 71; cannabis: 3.86), younger age (alcohol: 0.97), less education (alcohol, tobacco, cannabis and cocaine/crack comparing several lower schooling categories vs. higher education), lower income (alcohol: 0.42; tobacco: 0.47; and cannabis: 0.36), and higher depression DASS-21 score (alcohol: 1.05; tobacco: 1.08; cannabis: 1.07; and cocaine/crack: 1.07) were associated with higher use prevalence of several drugs.

CONCLUSIONS

Individuals reporting low social distancing increased the use of most drugs during the pandemic, while high social distancing significantly decreased drug use. Anxiety and depressive states and several sociodemographic factors (men; lower income; less education) were associated with higher drug use patterns.

Elevated GABA levels in the medial prefrontal cortex and lower estrogen levels abolish cocaine sensitization behavior in ovariectomized female rats

Animal models show that cocaine sensitization, a behavioral marker of addiction, is more significant in intact gonadal female than male rats and ovariectomy suppress this behavior in female rats. However, few studies explore changes in neurotransmission related to this phenomenon. Here we investigated the in vivo changes on GABA, glutamate, and taurine levels in the medial prefrontal cortex (mPFC) of gonadal intact or ovariectomized female rats after a cocaine challenge administration. Adult female rats were bilaterally ovariectomized (OVX), or sham-operated (SHAM) and randomly assigned to control (CTR), acute (ACT), or repeated (RPT) cocaine administration groups. In the challenge day, after eight days of daily cocaine (15 mg/kg) or saline administration and ten days of washout and stereotaxic surgery, RPT and ACT groups received cocaine, and the CTR group received saline. Horizontal locomotion was monitored concomitantly with microdialysate collection to determine extracellular GABA, glutamate, and taurine levels. Hormonal determination in blood samples confirmed the lower hormonal status of the OVX. Cocaine sensitization occurred in SHAM-RPT female rats after the challenge administration. Non-sensitized OVX-RPT rats showed a peak of GABA at 30 min after cocaine administration, with no change on glutamate and taurine levels. Therefore, elevated GABA levels in the mPFC and lower serum estrogen levels abolish cocaine sensitization behavior in ovariectomized female rats. We discuss some possible implications of these finding for future models of cocaine sensitization research lighting in the female hormonal influence.

The role of allopregnanolone in depressive-like behaviors: Focus on neurotrophic proteins

Allopregnanolone (3α,5α-tetrahydroprogesterone; pharmaceutical formulation: brexanolone) is a neurosteroid that has recently been approved for the treatment of postpartum depression, promising to fill part of a long-lasting gap in the effectiveness of pharmacotherapies for depressive disorders. In this review, we explore the experimental research that characterized the antidepressant-like effects of allopregnanolone, with a particular focus on the neurotrophic adaptations induced by this neurosteroid in preclinical studies. We demonstrate that there is a consistent decrease in allopregnanolone levels in limbic brain areas in rodents submitted to stress-induced models of depression, such as social isolation and chronic unpredictable stress. Further, both the drug-induced upregulation of allopregnanolone or its direct administration reduce depressive-like behaviors in models such as the forced swim test. The main drugs of interest that upregulate allopregnanolone levels are selective serotonin reuptake inhibitors (SSRIs), which present the neurosteroidogenic property even in lower, non-SSRI doses. Finally, we explore how these antidepressant-like behaviors are related to neurogenesis, particularly in the hippocampus. The protagonist in this mechanism is likely the brain-derived neurotrophic factor (BFNF), which is decreased in animal models of depression and may be restored by the normalization of allopregnanolone levels. The role of an interaction between GABA and the neurotrophic mechanisms needs to be further investigated.

Correlations between subunits of GABAA and NMDA receptors after chronic alcohol treatment or withdrawal, and the effect of taurine in the hippocampus of rats

Chronic use of alcohol and its withdrawal impairs the delicate balance between GABAergic and glutamatergic systems. This imbalance includes changes in GABA receptors - importantly in GABA_A subtypes - and glutamate receptors, especially in NMDA subtypes. A better comprehension of the different roles of GABA_AR and NMDAR subunits could be helpful to define new strategies to counteract the deleterious effects observed during alcohol withdrawal. Taurine, a sulfonated amino acid, has been proposed to attenuate alcohol withdrawal symptoms due to its neuromodulatory properties. In this study, we evaluated the correlations between GABA_AR and NMDAR subunits in the hippocampus of rats chronically treated with alcohol or in alcohol withdrawal, and the effects of taurine treatment on these parameters. Male Wistar rats received alcohol (2 g/kg) or water by oral gavage (control), 2 × /day, for 28 days. From day 29 to day 33, withdrawal rats received water instead of alcohol and all groups were reallocated to receive 100 mg/kg taurine or saline intraperitoneally (i.p.), once a day. On day 34, rats were euthanized and the hippocampus was dissected for GABA_AR α1, α4, δ, and γ2 and NMDAR GluN2A and GluN2B subunits mRNA expression determination by RT qPCR. There were no differences between groups in the studied GABA_AR and NMDA subunits. However, we observed a correlation of α1 and γ2 subunits induced by taurine, while in the alcohol group there was a correlation between α4 and GluN2A. In the group treated with alcohol and taurine, we observed an extra correlation, between α1 and GluN2A. After 5 days of withdrawal, a correlation observed in the control group, between δ and GluN2A, was reestablished. The correlation found between subunits suggests a neuroadaptation of GABAergic and glutamatergic systems in withdrawal rats. Results from this study contribute to the elucidation of the mechanisms beyond neuroadaptations observed in alcohol use and withdrawal.

Hemisphere-dependent Changes in mRNA Expression of GABAA Receptor Subunits and BDNF after Intra-prefrontal Cortex Allopregnanolone Infusion in Rats

Allopregnanolone is a neurosteroid implicated in mood disorders such as depression and anxiety. It acts as a GABA_A receptor (GABA_AR)-positive allosteric modulator and changes the expression of GABA_AR subunits and of brain-derived neurotrophic factor (BDNF) in different brain regions. It has been demonstrated that such neurochemical changes may have an asymmetrical pattern regarding brain hemispheres. The aim of this study was to verify the behavioral and hemisphere-specific neurochemical effects of the bilateral intra-prefrontal cortex (intra-PFC) infusion of allopregnanolone in rats. Rats were exposed to the forced swim test and to the grooming microstructure test, followed by the right and left hemisphere-specific quantification of mRNA expression by Real-Time PCR of δ and γ2 GABA_AR subunits and BDNF in the PFC and in the hippocampus. Though we did not observe any significant effects in the behavioral tests, intra-PFC allopregnanolone infusion bilaterally increased the mRNA expression of the δ subunit in the same area and of BDNF in the hippocampus. Both mRNA expressions of the γ2 subunit and BDNF were higher in the right than in the left PFC of control animals, and the hemisphere differences were not seen after allopregnanolone infusion. Overall hippocampal BDNF expression was also higher in the right hemisphere, but this asymmetry was not normalized by allopregnanolone. No asymmetries or changes were observed in the hippocampal mRNA expression of GABA_AR subunits. These results point to a hemisphere-dependent regulation of GABA_AR subunits and BDNF that can be modulated by intra-PFC allopregnanolone infusion, even in the absence of associated behavioral effects.

The effect of intracerebroventricular allopregnanolone on depressive-like behaviors of rats selectively bred for high and low immobility in the forced swim test

Depression is a highly incapacitating disorder known to have a multifactorial etiology, including a hereditary genetic background. The neurosteroid allopregnanolone (ALLO) is a positive allosteric modulator of the GABA_A receptor and has been shown to have an antidepressant-like effect in animals. This study aimed to assess the behavioral effect of ALLO in animals with different backgrounds of depressive-like activity. An initial population (F0) of male and female Wistar rats was screened for immobility behavior utilizing the Forced Swim Test (FST). Rats with extreme immobility scores were selected for either the High Immobility (HI) group or the Low Immobility (LI) group for breeding, giving origin to the subsequent generations F1 and F2. Guide cannulas were implanted in the lateral ventricle of F2 males for intracerebroventricular infusions of 5 μg/rat of ALLO, 5 μg/rat of imipramine (IMI) or vehicle (CTR), which occurred 24, 5 and 1 h prior to the test session of the drug FST. In the pre-drug FST, a statistically significant difference was observed between the immobility scores from the HI and LI groups of F2 rats. HI rats from F2 also showed significantly higher immobility time when compared to F0. In these HI animals, both IMI and ALLO significantly reduced immobility when compared to the CTR group. IMI-treated rats also showed lower immobility than the ALLO group. In the LI rats, no difference in immobility was found between treatments. In conclusion, two strains of rats with significantly different immobility profiles in the FST were obtained in a relatively short time, after only two generations. Infusions of both ALLO and IMI showed a strain-dependent antidepressant-like effect, being detected in the HI animals but not in the LI animals, which is in line with the clinical understanding that antidepressants have higher efficacy in more severe forms of depression.

Diabetic encephalopathy-related depression: experimental evidence that insulin and clonazepam restore antioxidant status in rat brain

There is increasing evidence suggesting that oxidative stress plays an important role in the development of many chronic and degenerative conditions such as diabetic encephalopathy and depression. Considering that diabetic rats and mice present higher depressive-like behaviour when submitted to the forced swimming test and that treatment with insulin and/or clonazepam is able to reverse the behavioural changes of the diabetic rats, the present work investigated the antioxidant status, specifically total antioxidant reactivity and antioxidant potential of insulin and clonazepam, as well as the effect of this drugs upon protein oxidative damage and reactive species formation in cortex, hippocampus and striatum from diabetic rats submitted to forced swimming test. It was verified that longer immobility time in diabetic rats and insulin plus clonazepam treatment reversed this depressive-like behaviour. Moreover, data obtained in this study allowed to demonstrate through different parameters such as protein carbonyl content, 2'7'-dichlorofluorescein oxidation, catalase, superoxide dismutase, glutathione peroxidase assay, total radical-trapping antioxidant potential and total antioxidant reactivity that there is oxidative stress in cortex, hippocampus and striatum from diabetic rats under depressive-like behaviour and highlight the insulin and/or clonazepam effect in these different brain areas, restoring antioxidant status and protein damage.

Behavioral effects of endogenous or exogenous estradiol and progesterone on cocaine sensitization in female rats

Cocaine sensitization is a marker for some facets of addiction, is greater in female rats, and may be influenced by their sex hormones. We compared the modulatory effects of endogenous or exogenous estradiol and progesterone on cocaine-induced behavioral sensitization in 106 female rats. Ovariectomized female rats received progesterone (0.5 mg/mL), estradiol (0.05 mg/mL), progesterone plus estradiol, or the oil vehicle. Sham-operated control females received oil. Control and acute subgroups received injections of saline, while the repeated group received cocaine (15 mg/kg, ip) for 8 days. After 10 days, the acute and repeated groups received a challenge dose of cocaine, after which locomotion and stereotypy were monitored. The estrous cycle phase was evaluated and blood was collected to verify hormone levels. Repeated cocaine treatment induced overall behavioral sensitization in female rats, with increased locomotion and stereotypies. In detailed analysis, ovariectomized rats showed no locomotor sensitization; however, the sensitization of stereotypies was maintained. Only females with endogenous estradiol and progesterone demonstrated increased locomotor activity after cocaine challenge. Estradiol replacement enhanced stereotyped behaviors after repeated cocaine administration. Cocaine sensitization of stereotyped behaviors in female rats was reduced after progesterone replacement, either alone or concomitant with estradiol. The behavioral responses (locomotion and stereotypy) to cocaine were affected differently, depending on whether the female hormones were of an endogenous or exogenous origin. Therefore, hormonal cycling appears to be an important factor in the sensitization of females. Although estradiol increases the risk of cocaine sensitization, progesterone warrants further study as a pharmacological treatment in the prevention of psychostimulant abuse.

Brain effect of insulin and clonazepam in diabetic rats under depressive-like behavior

Diabetes mellitus is characterized by hyperglycemia resulting from defects on insulin secretion, insulin action, or both. It has recently become clear that the central nervous system is not spared from the deleterious effects of diabetes, since diabetic encephalopathy was recognized as a complication of this heterogeneous metabolic disorder. There is a well recognized association between depression and diabetes, once prevalence of depression in diabetic patients is higher than in general population, and clonazepam is being used to treat this complication. Oxidative stress is widely accepted as playing a key mediatory role in the development and progression of diabetes and its complications. In this work we analyzed DNA damage by comet assay and lipid damage in prefrontal cortex, hippocampus and striatum of streptozotocin-induced diabetic rats submitted to the forced swimming test. It was verified that the diabetic group presented DNA and lipid damage in the brain areas evaluated, when compared to the control groups. Additionally, a significant reduction of the DNA and lipid damage in animals treated with insulin and/or clonazepam was observed. These data suggest that the association of these two drugs could protect against DNA and lipid damage in diabetic rats submitted to the forced swimming test, an animal model of depression.

The association effect of insulin and clonazepam on oxidative stress in liver of an experimental animal model of diabetes and depression

CONTEXT

It is known that oxidative stress occurs in peripheral blood in an experimental animal model of diabetes and depression, and acute treatment with insulin and clonazepam (CNZ) has a protective effect on oxidative stress in this model.

OBJECTIVE

This study evaluated the effect of insulin plus CNZ on oxidative stress parameters in the liver of diabetic male rats induced with streptozotocin (STZ) and subjected to forced swimming test (FST).

MATERIALS AND METHODS

Diabetes was induced by a single intraperitoneal (i.p.) dose of STZ 60 mg/kg in male Wistar rats. Insulin (4 IU/kg) plus CNZ acute i.p. treatment (0.25 mg/kg) was administered 24, 5 and 1 h before the FST. Nondiabetic control rats received i.p. injections of saline (1 mL/kg). Protein oxidative damage was evaluated by carbonyl formation and the antioxidant redox parameters were analyzed by the measurements of enzymatic activities of the superoxide dismutase (SOD), catalase and glyoxalase I (GLO). Glycemia levels also were determined.

RESULTS

Our present study has shown an increase in carbonyl content from diabetic rats subjected to FST (2.04 ± 0.55), while the activity of catalase (51.83 ± 19.02) and SOD (2.30 ± 1.23) were significantly decreased in liver from these animals, which were reverted by the treatment. Also, the activity of GLO (0.15 ± 0.02) in the liver of the animals was decreased.

DISCUSSION AND CONCLUSION

Our findings showed that insulin plus CNZ acute treatment ameliorate the antioxidant redox parameters and protect against protein oxidative damage in the liver of diabetic rats subjected to FST.

Antidepressant effect and changes of GABAA receptor gamma2 subunit mRNA after hippocampal administration of allopregnanolone in rats

The present study aimed to verify the effect of bilateral intra-hippocampus administration of the neurosteroid allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one; 3alpha, 5alpha-THP) in the forced swimming test (FST) and in the alpha4 and gamma2 GABA(A) receptor subunits gene expression. Results showed that bilateral intra-hippocampal allopregnanolone administration of 2.5 microg/rat ( P<0.05) reduced immobile behavior and increased climbing behavior in the FST. Overall, for all doses of allopregnanolone tested (1.25, 2.5, 5.0 microg/rat), an increase of gamma2 (P<0.05) GABA(A) subunit mRNA was observed. There was a higher increase in the gamma2 gene expression in the right hemisphere than in the left hemisphere (P<0.01) after allopregnanolone treatment. Intra-hippocampal allopregnanolone did not change the expression of the alpha4 subunits. In conclusion, intra-hippocampal administration of allopregnanolone produces an antidepressant-like effect in the FST at an intermediate dose, confirming the potential of neurosteroids as a new class of antidepressant drugs. Our findings suggest that the gamma2, but not the alpha4 GABA(A) subunit, needs further evaluation to be involved in the antidepressant effect of allopregnanolone in the hippocampus and that there is a hemispheric diversity in the biochemical effect of the drug.