Cannabis use in adult population in Galicia: Prevalence and associated characteristics

Cannabis is the most widely consumed illegal drug in Spain, with consumption concentrated mainly in adolescence and early adulthood. The objectives were to estimate the prevalence of cannabis use, cannabis use disorder (CUD) and dependent use in the Galician population aged 16 years and over, and to characterize cannabis users and cannabis dependent users. Data are from two cross-sectional studies from the Risk Behavior Information System conducted in 2017 (n = 7,841) and 2018 (n = 7,853). The Cannabis Abuse Screening Test (CAST) was used to identify users with CUD and/or dependent use. Prevalences were estimated and regression models were fitted to identify variables associated with cannabis use and dependent use. In 2017-2018, 2.7% (95% CI: 2.5-3.0) of the Galician population aged 16 years and over consumed cannabis at the time of the survey, with this prevalence being 9% in the 16-24 years age group. Prevalence decreased with age and was higher in males in all age groups. The prevalence of CUD in users was 69.5% (95% CI 61.1-78.1) and of dependent use it was 49.2% (95% CI 46.6-53.9). Tobacco use was the major determinant of being a cannabis user [OR = 19.8 (95% CI 13.8-28.4)] and daily cannabis use of being a dependent user [OR = 5.5 (95% CI 3.2-9.5)]. Cannabis use among the Galician population is high, especially among young people aged 16-24 years, who show the highest probability of dependent use. Prevention measures should be aimed especially at the younger population aged 16 years to curb its use and the development of consequences such as CUD and dependent use.

Validation of a novel and accurate ApoE4 assay for automated chemistry analyzers

The allele ε4 of the apolipoprotein E gene (APOE ε4) is the major genetic risk factor for non-dominantly inherited Alzheimer’s Disease (AD). Current techniques for APOE ε4 carriers identification show good accuracy but have several disadvantages that limit its implementation in a clinical laboratory. These include the need for sample preprocessing, poor automation, low throughput, requirement of additional equipment, and high cost. We followed ISO 13485 guidelines to validate the e4Risk test, a new latex-enhanced immunoturbidimetric blood assay for apolipoprotein E4 (ApoE4) determination in human plasma samples. The test showed high performance in terms of lot to lot variability, precision, interferences, reagents stability, prozone, and detectability. Furthermore, diagnostic accuracy is almost equal (99%) to the gold standard, APOE ε4 genotyping by polymerase chain reaction (PCR). Furthermore, we demonstrated that the e4Risk test can be adapted to any clinical chemistry analyzer, including the high throughput analyzers present in most hospitals and clinical laboratories. The e4Risk test versatility, low cost, and easiness provides an excellent solution for APOE ε4 carriers identification using the same blood sample drawn for biochemical diagnostic work-up of AD patients, which can have important advantages for patient stratification in clinical trials, preventative strategies for AD, and clinical assessment of risk for brain amyloidosis.

A fast and cost-effective method for apolipoprotein E isotyping as an alternative to APOE genotyping for patient screening and stratification

Apolipoprotein E (apoE) is a 34 kDa glycoprotein involved in lipid metabolism. The human APOE gene encodes for three different apoE protein isoforms: E2, E3 and E4. The interest in apoE isoforms is high for epidemiological research, patient stratification and identification of those at increased risk for clinical trials and prevention. The isoform apoE4 is associated with increased risk for coronary heart and Alzheimer's diseases. This paper describes a method for specifically detecting the apoE4 isoform from biological fluids by taking advantage of the capacity of apoE to bind "specifically" to polystyrene surfaces as capture and a specific anti-apoE4 monoclonal antibody as reporter. Our results indicate that the apoE-polystyrene binding interaction is highly stable, resistant to detergents and acid and basic washes. The methodology here described is accurate, easily implementable, fast and cost-effective. Although at present, our technique is unable to discriminate homozygous APOE ε4/ε4 from APOE ε3/ε4 and ε2/ε4 heterozygous, it opens new avenues for the development of inexpensive, yet effective, tests for the detection of apoE4 for patients' stratification. Preliminary results indicated that this methodology is also adaptable into turbidimetric platforms, which make it a good candidate for clinical implementation through its translation to the clinical analysis routine.

Quantitative Metabolomics in Alzheimer's Disease: Technical Considerations for Improved Reproducibility

Metabolomics is the comprehensive analysis of small molecules (metabolites) that are intermediates or endpoints of metabolism. Since metabolites change more rapidly to both external and internal stimuli than genes and proteins, metabolomics provides a more sensitive tool to study physiological changes to a wide range of factors such age, medication, or disease status. Therefore, metabolomics is being increasingly used for the study of several pathological states, including complex diseases like Alzheimer's disease (AD).Both untargeted and targeted metabolomics have been applied for AD and both have provided diagnostic algorithms that accurately discriminate healthy patients from patients with AD by combining different metabolites. However, none of these algorithms have been replicated in larger, different cohorts, and a consensus in methodology has been claimed by the scientific community. The AbsoluteIDQ^® p180 Kit (Biocrates, Life Science AG, Innsbruck, Austria) is to date the only commercially available, validated, and standardized assay that measures up to 188 metabolites in biological samples. This kit unifies methodology in a common user manual and provides quantitative measurements of metabolites, thus facilitating an easier comparison among studies and reducing the technical variability that might contribute to replication failures. Nevertheless, recent studies showed no replication even when using this kit, suggesting that additional measures should be taken to achieve replication of metabolite-based discriminative algorithms. The aim of this chapter is to provide technical guidance on how to apply quantitative metabolomic data to the definition of discriminative algorithms for the diagnosis of neurodegenerative diseases such as AD. This chapter will provide an overview of technical aspects on the whole process, from blood sampling to raw data handling, and will highlight several technical aspects in the process that could hamper replication attempts even when using validated and standardized assays, such as the AbsoluteIDQ^® p180 Kit.

Impacts of climate and land use changes on the hydrological and erosion processes of two contrasting Mediterranean catchments

The impacts of climate and land use changes on streamflow and sediment export were evaluated for a humid (São Lourenço) and a dry (Guadalupe) Mediterranean catchment, using the SWAT model. SWAT was able to produce viable streamflow and sediment export simulations for both catchments, which provided a baseline for investigating climate and land use changes under the A1B and B1 emission scenarios for 2071-2100. Compared to the baseline scenario (1971-2000), climate change scenarios showed a decrease in annual rainfall for both catchments (humid: -12%; dry: -8%), together with strong increases in rainfall during winter. Land use changes were derived from a socio-economic storyline in which traditional agriculture is replaced by more profitable land uses (i.e. corn and commercial forestry at the humid site; sunflower at the dry site). Climate change projections showed a decrease in streamflow for both catchments, whereas sediment export decreased only for the São Lourenço catchment. Land use changes resulted in an increase in streamflow, but the erosive response differed between catchments. The combination of climate and land use change scenarios led to a reduction in streamflow for both catchments, suggesting a domain of the climatic response. As for sediments, contrasting results were observed for the humid (A1B: -29%; B1: -22%) and dry catchment (A1B: +222%; B1: +5%), which is mainly due to differences in the present-day and forecasted vegetation types. The results highlight the importance of climate-induced land-use change impacts, which could be similar to or more severe than the direct impacts of climate change alone.

SOD1 overexpression improves features of the oligodendrocyte precursor response in vitro

Spinal cord injury (SCI) produces a significant loss of oligodendrocytes (OL) and demyelination. The oligodendrocyte precursor cells (OPCs) response includes a group of cellular changes in OPCs that are directed to replenish OL loss from the injury. However, this adaptive response is hampered and OPCs eventually die or fail to differentiate to mature and functional OL. In this study, we wanted to evaluate if overexpression of human superoxide dismutase 1 (hSOD1) in OPCs from the SOD1 transgenic rat could improve some of the features of the OPC response in vitro. We found that hSOD1 overexpression increases the proliferation of OPCs and accelerates their differentiation to mature OL in vitro. Furthermore, hSOD1 overexpression reduces oxidative stress-mediated death in OPCs. These results suggest hSOD1 as a therapeutic target to increase OPC response success and potentially, OL replacement and remyelination after SCI.

Previous cycling does not affect running efficiency during a triathlon world cup competition

AIM

The most strategic part of a triathlon is the cycle-run transition. However, all the studies about this situation have been carried out in laboratory conditions and there is a need to perform this kind of study during competition, when the triathletes are highly motivated and the effort is maximum.1 Therefore, the aims of the present study were: 1) to determine the effect of prior 40-km cycling on the 10-km running kinematics during a Triathlon World Cup competition, and 2) to examine the possible differences between males and females.

METHODS

Ten men and ten women, selected among the first ten competitors at the end of the cycling part at Madrid 2006 BG Triathlon World Cup, were enrolled in the study. The kinematic analysis was carried out using a photogrammetric technique (DLT algorithms) in the saggital plane (2D).

RESULTS

There are significant differences (P<0.05) in men's stride length and velocity between the first and the last lap. Also, significant differences (P<0.05) were found between men and women in many of the variables analyzed.

CONCLUSIONS

The previous cycling does not affect the subsequent running efficiency during a elite triathlon competition. On the other hand, the running technique profile during a triathlon competition is very different between men and women.

Translocator protein 18 kDa is involved in the regulation of reactive gliosis

Translocator protein (18 kDa) (TSPO), previously known as peripheral-type benzodiazepine receptor, is a critical component of the mitochondrial permeability transition pore. Brain inflammation results in the induction of the expression of TSPO in glial cells and some TSPO ligands decrease reactive gliosis after brain injury. However, since some TSPO ligands are neuroprotective, their effects on reactive gliosis may be the consequence of a reduced neurodegeneration. To assess whether TSPO ligands can modulate reactive gliosis in absence of neuronal death, we have tested their effects on the inflammatory response induced in the hippocampus of male rats by the intracerebroventricular infusion of lipopolysaccharide (LPS). LPS treatment did not induce neuronal death, assessed by Fluoro jade-B staining, but increased the number of cells immunoreactive for vimentin and MHC-II, used as markers of reactive astrocytes and reactive microglia, respectively. Furthermore, LPS produced an increase in the number of proliferating microglia. The TSPO ligand PK11195 reduced the number of MHC-II immunoreactive cells and the proliferation of microglia in LPS treated rats. In contrast, another TSPO ligand, Ro5-4864, did not significantly affect the response of microglia to LPS. Neither PK11195 nor Ro5-4864 affected the LPS-mediated increase in the number of vimentin-immunoreactive astrocytes at the time point studied, although PK11195 reduced vimentin immunoreactivity. These findings identify TSPO as a potential target for controlling neural inflammation, showing that the TSPO ligand PK11195 may reduce microglia activation by a mechanism that is independent of the regulation of neuronal survival.

Rapid and deep control of inflammation in rheumatoid arthritis with infliximab and its correlation with acute-phase reactants

Rheumatoid arthritis (RA) is a chronic inflammatory disease with predominant joint involvement and possible systemic compromise, which leads to a handicapped status and poor quality of life. An optimal approach to treat RA requires early and intensive intervention with close monitoring of treatment response. Tumor necrosis factor (TNF) blockers are recommended in cases of active RA after the unsuccessful use of effective disease-modifying antirheumatic drugs (DMARDs); even adding them to treatment or replacing these drugs. Anti-TNF therapies have been demonstrated to reduce significant joint damage and to relieve symptoms during a prolonged time (see Scott and Kingsley, 2006). The efficacy of infliximab in an open-label trial is summarized with respect to speed of onset of action, durability of response, and its correlation between clinical and laboratory parameters. Safety for long-term treatment is also summarized. We studied 105 RA patients with more than 3 years' history of disease during 24 months on i.v. infliximab (75 completed study). We evaluated ACR responses at base line, and at 1, 6, 12, 16, 52, 77, and 104 weeks. Morning stiffness, swollen and tender joints, HAQ, SF-36% (PCS/MCS), polymerase chain reaction (PCR), erythrosedimentation rate (ESR), transaminases, rheumatoid factor (RF) levels, hemogram, and adverse events profile were all assessed. The treatment offered rapid and sustained clinical improvements as revealed by ACR responses and marked changes in the parameters previously described. Important changes were made in functional status and acute-phase reactants. Finally, infliximab was considered well tolerated and did not affect the safety profile of this trial.

Testosterone decreases reactive astroglia and reactive microglia after brain injury in male rats: role of its metabolites, oestradiol and dihydrotestosterone

Previous studies have shown that the neuroprotective hormone, testosterone, administered immediately after neural injury, reduces reactive astrogliosis. In this study we have assessed the effect of early and late therapy with testosterone or its metabolites, oestradiol and dihydrotestosterone, on reactive astroglia and reactive microglia after a stab wound brain injury in orchidectomized Wistar rats. Animals received daily s.c. injections of testosterone, oestradiol or dihydrotestosterone on days 0-2 or on days 5-7 after injury. The number of vimentin immunoreactive astrocytes and the volume fraction of major histocompatibility complex-II (MHC-II) immunoreactive microglia were estimated in the hippocampus in the lateral border of the wound. Both early and delayed administration of testosterone or oestradiol, but not dihydrotestosterone, resulted in a significant decrease in the number of vimentin-immunoreactive astrocytes. The volume fraction of MHC-II immunoreactive microglia was significantly decreased in the animals that received testosterone or oestradiol in both early and delayed treatments and in animals that received early dihydrotestosterone administration. Thus, both early and delayed administration of testosterone reduces reactive astroglia and reactive microglia and these effects may be at least in part mediated by oestradiol, while dihydrotestosterone may mediate part of the early effects of testosterone on reactive microglia. In conclusion, testosterone controls reactive gliosis and its metabolites, oestradiol and dihydrotestosterone, may be involved in this hormonal effect. The regulation of gliosis may be part of the neuroprotective mechanism of testosterone.

[The role of the human histocompatibility antigens in the pathogenesis of neurological disorders]

INTRODUCTION

Several studies have been trying to define genetic markers of neurological disorders. Among them, antigens and alleles of the HLA (human leukocyte antigens) system are distinguished. The HLA exerts genetic influence on the susceptibility, clinical aspects and severity of many diseases. The discovery of new molecular methods to typify HLA alleles and the recent nomenclature updates have been contributing to a better understanding of this system. Unfortunately, this information has not been adequately published in the clinical literature.

AIM

To review the structure, function, nomenclature and methods of detection of the HLA polymorphism and its associations with common neurological disorders.

DEVELOPMENT

Articles that were published between 1990 and 2004 were searched in the MEDLINE and LILACS databases. This review demonstrated that although the HLA association is well established for some neurological disorders (e.g., HLA-DQB1*0602 with multiple sclerosis and narcolepsy; HLA-B7 e HLA-A2 with Alzheimer's disease; HLA-DR3-DR8 with Lamber-Eaton syndrome; and HLA class II Parkinson's disease and amyotrophic lateral sclerosis), these associations are not consistent and vary in different ethnic groups.

CONCLUSIONS

It is necessary to study populations from different ethnic backgrounds to identify new associations or to strength the ones already identified. This knowledge will contribute in the evaluation of the risk that a person carrying a particular allele or haplotype has to develop a neurological disease and therefore contribute towards a better understanding of its pathogenesis.

Neuroactive steroids prevent peripheral myelin alterations induced by diabetes

The effect of the neuroactive steroids progesterone, dihydroprogesterone and tetrahydroprogesterone on myelin abnormalities induced by diabetes was studied in the sciatic nerve of adult male rats treated with streptozotocin. Streptozotocin increased blood glucose levels and decreased body weight gain, parameters not affected by steroids. Streptozotocin increased the number of fibers with myelin infoldings in the axoplasm, 8 months after the treatment. Chronic treatment for 1 month with progesterone and dihydroprogesterone resulted in a significant reduction in the number of fibers with myelin infoldings to control levels. Treatment with tetrahydroprogesterone did not significantly affect this myelin alteration. These results suggest that neuroactive steroids such as progesterone and dihydroprogesterone may represent therapeutic alternatives to counteract peripheral myelin alterations induced by diabetes.

Sex-dimorphic effects of progesterone and its reduced metabolites on gene expression of myelin proteins by rat Schwann cells

Data obtained in our and other laboratories have indicated that progesterone (P) and its derivatives, dihydroprogesterone (DHP) and tetrahydroprogesterone (THP), stimulate the expression of two myelin proteins of the peripheral nervous system (PNS) [i.e., glycoprotein zero (P0) and peripheral myelin protein 22 (PMP22)]. We have now considered the effects of P and its derivatives on these and other myelin proteins [i.e., myelin-associated glycoprotein (MAG) and myelin and lymphocyte protein (MAL)] in sex-specific cultures of rat Schwann cells. Gene expression of myelin proteins was assessed by RNase protection assay. Treatment with P or DHP induced a stimulatory effect on P0 mRNA levels in male but not in female Schwann cells. In contrast, treatment with THP increased gene expression of P0 exclusively in female Schwann cells. A similar sex-difference was also evident for other myelin proteins. Indeed, PMP22 expression was stimulated by treatment with P in male cultures, whereas THP induced an increase of mRNA levels in female cultures. Moreover, MAG was stimulated by THP treatment in male cultures only, whereas MAL expression was unaffected by neuroactive steroid treatment in both male and female cultures. In conclusion, the present observations indicate that the effects of neuroactive steroids on myelin proteins are sexually dimorphic. This finding might represent an important background for sex-specific therapies of acquired and inherited peripheral neuropathies.

Extragonadal synthesis of estradiol is protective against kainic acid excitotoxic damage to the hippocampus

Gonadal or exogenous estradiol is neuroprotective in multiple experimental paradigms. The role exerted by endogenous extragonadal estradiol synthesis in neuroprotection, however, is poorly understood. Here we show that a dose of kainic acid (3 mg/kg body weight) that does not produce detectable neuronal damage in control male and female gonadectomized rats induces a significant loss of hippocampal hilar neurons after the systemic inhibition of aromatase, the enzyme involved in estradiol biosynthesis from androgens. Extragonadal aromatase inhibition exerts a similar neuronal loss in both male and female rats (26% and 30% reduction in the number of hilar neurons, respectively). These findings indicate that extragonadal estradiol exerts a neuroprotective effect in both sexes, which prevents neuronal loss as a consequence of mild neurodegenerative signals.

Ro5-4864, a peripheral benzodiazepine receptor ligand, reduces reactive gliosis and protects hippocampal hilar neurons from kainic acid excitotoxicity

The peripheral-type benzodiazepine receptor (PBR) is a critical component of the mitochondrial permeability transition pore, which is involved in the regulation of cell survival. Different forms of brain injury result in induction of the expression of the PBR in the areas of neurodegeneration, mainly in reactive glial cells. The consequences of induction of PBR expression after brain injury are unknown. To test whether PBR may be involved in the regulation of neuronal survival after injury, we have assessed the effect of two PBR ligands, Ro5-4864 and PK11195, on neuronal loss induced by kainic acid in the hippocampus. Systemic administration of kainic acid to male rats resulted in the induction of a reactive phenotype in astrocytes and microglia and in a significant loss of hilar neurons in the dentate gyrus. Administration of Ro5-4864, before the injection of kainic acid, decreased reactive gliosis in the hilus and prevented hilar neuronal loss. In contrast, PK11195 was unable to reduce reactive gliosis and did not protect hilar neurons from kainic acid. These findings suggest that the PBR is involved in control of neuronal survival and gliosis after brain injury and identify this molecule as a potential target for neuroprotective interventions.

Sex hormones and brain aging

Sex steroids exert pleiotropic effects in the nervous system, preserving neural function and promoting neuronal survival. Therefore, the age-related decrease in sex steroids may have a negative impact on neural function. Progesterone, testosterone and estradiol prevent neuronal loss in the central nervous system in different experimental animal models of neurodegeneration. Furthermore, progesterone and its reduced derivatives dihydroprogesterone and tetrahydroprogesterone reduce aging-associated morphological abnormalities of myelin and aging-associated myelin fiber loss in rat peripheral nerves. However, the results from hormone replacement studies in humans are thus far inconclusive. A possible alternative to hormonal replacement therapy is to increase local steroidogenesis by neural tissues, which express enzymes for steroid synthesis and metabolism. Proteins involved in the intramitochondrial trafficking of cholesterol, the first step in steroidogenesis, such as the peripheral-type benzodiazepine receptor and the steroidogenic acute regulatory protein, are up-regulated in the nervous system after injury. Furthermore, steroidogenic acute regulatory protein expression is increased in the brain of 24-month-old rats compared with young adult rats. This suggests that brain steroidogenesis may be modified in adaptation to neurodegenerative conditions and to the brain aging process. Furthermore, recent studies have shown that local formation of estradiol in the brain, by the enzyme aromatase, is neuroprotective. Therefore, steroidogenic acute regulatory protein, peripheral-type benzodiazepine receptor and aromatase are attractive pharmacological targets to promote neuroprotection in the aged brain.

[The neuroprotective properties of sex steroids and neurosteroids]

INTRODUCTION

The nervous system is a target for steroid hormones as well as a steroidogenic tissue, and it produces steroids that have a paracrine or autocrine effect on neurons and glial cells. Steroids formed in nervous tissue are called neurosteroids in order to differentiate them, in terms of their origin, from the peripheral steroids, although they both share the same molecular structure.

DEVELOPMENT

We analyse the capacity of neurons and glial cells to synthesise steroids and describe the role played in steroidogenesis by certain key molecules, such as steroidogenic acute regulatory protein, peripheral benzodiazepine receptor and aromatase enzyme, which acts as a catalyst in the conversion of testosterone into estradiol. We also provide a description of the different mechanisms of action of the hormonal steroids and neurosteroids in the nervous system. These include both the regulation of protein synthesis by neurons and glial cells, by acting on nuclear receptors, and rapid effects mediated by membrane receptors or the allosteric modulation of neurotransmitter receptors. We review the clinical and experimental evidence for the neuroprotective effects of sex steroids and neurosteroids, and the limitations of hormone replacement therapy following menopause.

CONCLUSIONS

Given the restraints involved in the systemic use of hormones as neuroprotective therapy, alternative strategies that take advantage of the neuroprotective properties of steroids must be sought. These could involve locally increasing their synthesis inside the brain or developing molecules that activate the steroid receptors in the nervous system and not in the peripheral organs.

Brain steroidogenesis: emerging therapeutic strategies to prevent neurodegeneration

Decreasing levels of gonadal steroids with aging are associated to an increase in cognitive, neurological and psychiatric disturbances. Estradiol is neuroprotective in animal models of neurodegeneration. However, the effects of hormonal replacement therapy on brain function in postmenopausal women are controversial. A possible alternative to hormonal replacement therapy is to increase local brain steroidogenesis, since experimental studies indicate that local estrogen formation in the brain is neuroprotective.

Aromatase expression by reactive astroglia is neuroprotective

The enzyme aromatase catalyzes the conversion of testosterone and other C19 steroids to estradiol. Under normal circumstances, the expression of aromatase in the central nervous system of mammals is restricted to neurons. However, the expression of the enzyme is induced in astrocytes in vitro by stressful stimuli. Furthermore, different types of brain injury induce in vivo the expression of aromatase in reactive astrocytes. The expression of aromatase by reactive astrocytes is neuroprotective, because the pharmacological inhibition of the enzyme in the brain exacerbates neuronal death after different forms of mild neurodegenerative stimuli that do not significantly affect neuronal survival under control conditions. These findings indicate that the induction of aromatase in reactive astrocytes, and the consecutive increase in the local production of estradiol in the brain at injured sites, may be an endogenous neural response to reduce the extent of neurodegenerative damage.

Aromatase: a neuroprotective enzyme

Estradiol, in addition to its participation in neuroendocrine regulation and sexual behavior, has neuroprotective properties. Different types of brain injury induce the expression of the enzyme aromatase in reactive astroglia. This enzyme catalyzes the conversion of testosterone and other C19 steroids to estradiol. Genetic or pharmacological inhibition of brain aromatase results in marked neurodegeneration after different forms of mild neurodegenerative stimuli that do not compromise neuronal survival under control conditions. Furthermore, aromatase mediates neuroprotective effects of precursors of estradiol such as pregnenolone, dehydroepiandrosterone (DHEA) and testosterone. These findings strongly suggest that local formation of estradiol in the brain is neuroprotective and that the induction of aromatase and the consecutive increase in the local production of estradiol are part of the program triggered by the neural tissue to cope with neurodegenerative insults. Aromatase may thus represent an important pharmacological target for therapies conducted to prevent aging-associated neurodegenerative disorders.

Progesterone and its derivatives dihydroprogesterone and tetrahydroprogesterone reduce myelin fiber morphological abnormalities and myelin fiber loss in the sciatic nerve of aged rats

Previous studies indicate that steroid hormones may be protective for Schwann cells and promote the expression of myelin proteins in the sciatic nerve of adult rats. In this study, we have evaluated the effect of progesterone (P), dihydroprogesterone (DHP), tetrahydroprogesterone (THP), testosterone (T), dihydrotestosterone (DHT) and 5alpha-androstan-3alpha, 17beta-diol (3alpha-diol) on the morphological alterations of myelinated fibers in the sciatic nerve of 22-24-month-old male rats. The sciatic nerves of untreated old male rats, showed a general disorganization and a significant reduction in the density of myelinated fibers, compared to nerves from 3-month-old male rats. The effect of aging was particularly evident in myelinated fibers of small caliber (<5 microm in diameter). In addition, the sciatic nerves of old rats showed a significant increase in the number of fibers with myelin infoldings in the axoplasm and in the number of fibers with irregular shapes. Treatments of old rats with P, DHP and THP resulted in a significant increase in the number of myelinated fibers of small caliber, a significant reduction in the frequency of myelin abnormalities and a significant increase in the g ratio of small myelinated fibers. Furthermore, P treatment significantly reduced the frequency of myelinated fibers with irregular shapes. In contrast, treatments with T, DHT or 3alpha-diol did not significantly affect any of the morphological parameters examined. In conclusion, our data indicate that P, and its derivatives DHP and THP, are able to reduce aging-associated morphological abnormalities of myelin and aging-associated myelin fiber loss in the sciatic nerve. These data suggest that P, DHP and THP may represent useful therapeutic alternatives to maintain peripheral nerve integrity in aged animals.

Neuroprotection by the steroids pregnenolone and dehydroepiandrosterone is mediated by the enzyme aromatase

Pregnenolone and dehydroepiandrosterone (DHEA) are sex hormone precursors and neuroprotective steroids. Effects of pregnenolone and DHEA may be in part mediated by their conversion to testosterone and by the consecutive conversion of testosterone to estradiol by the enzyme aromatase. This enzyme is induced in reactive astrocytes after different forms of neurodegenerative lesions and the resultant local production of estradiol in the brain has been shown to be neuroprotective. The participation of aromatase in the neuroprotective effect of pregnenolone and DHEA has been assessed in this study. The protective effect of different doses (12.5, 25, 50, and 100 mg/kg) of pregnenolone or DHEA, against systemic kainic acid (7 mg/kg b.w.), was assessed on hippocampal hilar neurons in gonadectomized Wistar male rats. To determine whether the neuroprotective effect of pregnenolone and DHEA was dependent on their conversion to estradiol, the aromatase inhibitor fadrozole (4.16 mg/ml) was administered using subcutaneous osmotic minipumps. The number of Nissl-stained neurons in the hilus of the dentate gyrus of the hippocampal formation was estimated by the optical disector method. The administration of kainic acid resulted in a significant decrease in the number of hilar neurons compared to rats injected with vehicles. Pregnenolone and DHEA showed a dose-dependent protective effect of hilar neurons against kainic acid. The administration of the aromatase inhibitor fadrozole blocked the neuroprotective effect of pregnenolone and DHEA. These findings suggest that estradiol formation by aromatase mediates neuroprotective effects of pregnenolone and DHEA against excitotoxic-induced neuronal death in the hippocampus.

Neuroactive steroids influence peripheral myelination: a promising opportunity for preventing or treating age-dependent dysfunctions of peripheral nerves

The process of aging deeply influences morphological and functional parameters of peripheral nerves. The observations summarized here indicate that the deterioration of myelin occurring in the peripheral nerves during aging may be explained by the fall of the levels of the major peripheral myelin proteins [e.g., glycoprotein Po (Po) and peripheral myelin protein 22 (PMP22)]. Neuroactive steroids, such as progesterone (PROG), dihydroprogesterone (5alpha-DH PROG), and tetrahydroprogesterone (3alpha,5alpha-TH PROG), are able to stimulate the low expression of these two myelin proteins present in the sciatic nerve of aged male rats. Since Po and PMP22 play an important physiological role in the maintenance of the multilamellar structure of PNS myelin, we have evaluated the effect of PROG and its neuroactive derivatives, 5alpha-DH PROG and 3alpha,5alpha-TH PROG, on the morphological alterations of myelinated fibers in the sciatic nerve of 22-24-month-old male rats. Data obtained clearly indicate that neuroactive steroids are able to reduce aging-associated morphological abnormalities of myelin and aging-associated myelin fiber loss in the sciatic nerve.

Effects of neuroactive steroids on myelin of peripheral nervous system

Peripheral nervous system (PNS) possess both classical (e.g. progesterone receptor, PR, androgen receptor, AR) and non-classical (e.g. GABA(A) receptor) steroid receptors and consequently may represent a target for the action of neuroactive steroids. Our data have indicated that neuroactive steroids, like for instance, progesterone, dihydroprogesterone, tetrahydroprogesterone, dihydrotestosterone and 3alpha-diol, stimulate both in vivo and in vitro (Schwann cell cultures), the expression of two important proteins of the myelin of peripheral nerves, the glycoprotein Po (Po) and the peripheral myelin protein 22 (PMP22). It is important to highlight that the mechanisms by which neuroactive steroids exert their effects on the expression of Po and PMP22 involve different kind of receptors depending on the steroid and on the myelin protein considered. In particular, at least in culture of Schwann cells, the expression of Po seems to be under the control of PR, while that of PMP22 needs the GABA(A) receptor. Because Po and PMP22 play an important physiological role for the maintenance of the multilamellar structure of the myelin of the PNS, the present observations might suggest the utilization of neuroactive steroids as new therapeutically approaches for the rebuilding of the peripheral myelin.

Glial expression of estrogen and androgen receptors after rat brain injury

Estrogens and androgens can protect neurons from death caused by injury to the central nervous system. Astrocytes and microglia are major players in events triggered by neural lesions. To determine whether glia are direct targets of estrogens or androgens after neural insults, steroid receptor expression in glial cells was assessed in two different lesion models. An excitotoxic injury to the hippocampus or a stab wound to the parietal cortex and hippocampus was performed in male rats, and the resultant expression of steroid receptors in glial cells was assessed using double-label immunohistochemistry. Both lesions induced the expression of estrogen receptors (ERs) and androgen receptors (ARs) in glial cells. ERalpha was expressed in astrocytes immunoreactive (ERalpha-ir) for glial fibrillary acidic protein or vimentin. AR immunoreactivity colocalized with microglial markers, such as Griffonia simplicifolia lectin-1 or OX-6. The time course of ER and AR expression in glia was studied in the stab wound model. ERalpha-ir astrocytes and AR-ir microglia were observed 3 days after lesion. The number of ERalpha-ir and AR-ir glial cells reached a maximum 7 days after lesion and returned to low levels by 28 days postinjury. The studies of ERbeta expression in glia were inconclusive; different results were obtained with different antibodies. In sum, these results suggest that reactive astrocytes and reactive microglia are a direct target for estrogens and androgens, respectively.

Brain aromatase is neuroprotective

The expression of aromatase, the enzyme that catalyzes the biosynthesis of estrogens from precursor androgens, is increased in the brain after injury, suggesting that aromatase may be involved in neuroprotection. In the present study, the effect of inactivating aromatase has been assessed in a model of neurodegeneration induced by the systemic administration of neurotoxins. Domoic acid, at a dose that is not neurotoxic in intact male mice, induced significant neuronal loss in the hilus of the hippocampal formation of mice with reduced levels of aromatase substrates as a result of gonadectomy. Furthermore, the aromatase substrate testosterone, as well as its metabolite estradiol, the product of aromatase, were able to protect hilar neurons from domoic acid. In contrast, dihydrotestosterone, the 5 alpha-reduced metabolite of testosterone and a nonaromatizable androgen, was not. These findings suggest that aromatization of testosterone to estradiol may be involved in the neuroprotective action of testosterone in this experimental model. In addition, aromatase knock-out mice showed significant neuronal loss after injection of a low dose of domoic acid, while control littermates did not, indicating that aromatase deficiency increases the vulnerability of hilar neurons to neurotoxic degeneration. The effect of aromatase on neuroprotection was also tested in male rats treated systemically with the specific aromatase inhibitor fadrozole and injected with kainic acid, a well characterized neurotoxin for hilar neurons in the rat. Fadrozole enhanced the neurodegenerative effect of kainic acid in intact male rats and this effect was counterbalanced by the administration of estradiol. Furthermore, the neuroprotective effect of testosterone against kainic acid in castrated male rats was blocked by fadrozole. These findings suggest that neuroprotection by aromatase is due to the formation of estradiol from its precursor testosterone. Finally, a role for local cerebral aromatase in neuroprotection is indicated by the fact that intracerebral administration of fadrozole enhanced kainic acid induced neurodegeneration in the hippocampus of intact male rats. These findings indicate that aromatase deficiency decreases the threshold for neurodegeneration and that local cerebral aromatase is neuroprotective. Brain aromatase may therefore represent a new target for therapeutic approaches to neurodegenerative diseases.

Induction of spontaneous tail-flicks in rats by blockade of transmission at N-methyl-D-aspartate receptors: roles of multiple monoaminergic receptors in relation to the actions of antipsychotic agents

We examined the involvement of multiple monoaminergic receptors in the induction of spontaneous tail-flicks (STFs) by the open channel blocker at N-methyl-D-aspartate (NMDA) receptors, dizocilpine, and the NMDA recognition site antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). At doses eliciting a maximal STF response, dizocilpine and CPP elevated levels of norepinephrine, but not dopamine or serotonin, in dialysates of nucleus accumbens, their known locus of action in eliciting STFs. Chemically diverse alpha(2)-adrenergic receptor (AR) antagonists atipamezole, L745,743, RX821,002, idazoxan, and desfluparoxan abolished induction of STFs by dizocilpine, whereas the preferential alpha(1)-AR antagonists prazosin, WB4101, and ARC239 were weakly active: relative potencies in blocking STFs correlated significantly with affinity at alpha(2)-ARs. The D(1)/D(5) receptor antagonists SCH23390, SCH39166, and NNC756 potently abolished STFs, whereas the D(2) antagonist L741,626, the D(3) antagonists GR218,231 and S14297, and the D(4) antagonists S18126 and L745,870 were inactive. D(1) and alpha(2)-AR antagonists also blocked induction of STFs by CPP. Blockade of dizocilpine-induced STFs was specific inasmuch as idazoxan and SCH 23390 did not modify induction of ataxia by dizocilpine. Antagonists at multiple 5-hydroxytryptamine receptors failed to modify induction of STFs. Finally, dizocilpine-induced STFs were blocked by clozapine and 11 other antipsychotics, the potency of which correlated significantly with affinity at alpha(2)-ARs. In conclusion, STFs evoked by interruption of transmission at NMDA receptors are dependent on D(1) receptors and alpha(2)-ARs for their expression. Antagonism of the alpha(2)-ARs is involved in their blockade by antipsychotics. This model should facilitate exploration of interrelationships between glutamatergic and monoaminergic mechanisms involved in psychiatric and neurologic disorders.

Blockade of NMDA receptors in the nucleus accumbens elicits spontaneous tail-flicks in rats

The open channel blocker at N-methyl-D-aspartate (NMDA) receptors, dizocilpine, stereospecifically elicited spontaneous tail-flicks in rats - a reaction similar to those elicited by other drugs (tenocyclidine, phencyclidine and ketamine) acting as open channel blockers. Their relative potencies were strongly correlated with affinities at NMDA binding sites and labeled by [3H]dizocilpine in the frontal cortex (r=0.94) and, as determined previously [Millan, M. J., Seguin, L., 1994. Chemically-diverse ligands at the glycine B site coupled to N-methyl-D-aspartate (NMDA) receptors selectively block the late phase of formalin-induced pain in mice, Neurosci. Lett., 178 (1994) 139-143], potency for eliciting antinociception (0. 93). The competitive antagonists at the NMDA receptor recognition site, (+/-)3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), 4-phosphonomethyl-2-piperidine carboxylic acid (CGS19755), D, L-(E)-2-amino-4-methylphosphono-3-pentanoic acid (CGP37849) and (3E)-1-ethyl ester-2-amino-4-methyl-5-phosphono-3-pentenoic acid (CGP39551), likewise dose-dependently evoked spontaneous tail-flick. In contrast, antagonists/weak partial agonists at the coupled, glycine B site, 7-chloro-4-hydroxy-3-(3-phenoxy) phenyl-2(H)-quinolinone (L701,324), (+)-1-hydroxy-3-aminopyrrolidine-2-one ((+)-HA966), (3R, 4R)-3-amino-1-hydroxy-4-methyl-2-pyrrolidinone (L687,414), 6, 7-dichloro-1, 4-dihydro-5-nitro, 2,3 quinoxalinedione (ACEA1021) and 2-carboxy-4,6-dichloro (1H)-indole-3-propanoic acid (MDL29,951), were inactive. NMDA abolished induction of spontaneous tail-flick by CPP and CGS19755, but not by dizocilpine. Upon bilateral injection into the nucleus accumbens, dizocilpine immediately and dose-dependently elicited spontaneous tail-flick, but it was ineffective in the ventrotegmental area and striatum. Similarly, injection of CPP into the nucleus accumbens elicited spontaneous tail-flick. Neither dizocilpine nor CPP elicited spontaneous tail-flick upon administration onto lumbar spinal cord. In conclusion, a pharmacologically specific spontaneous tail-flick-response is elicited by both open channel blockers and recognition site antagonists, but not glycine B site antagonists, at NMDA receptors. Their actions, mediated in the nucleus accumbens, may be differentiated by their respective resistance and sensitivity to NMDA.

WAY 100,635 enhances both the 'antidepressant' actions of duloxetine and its influence on dialysate levels of serotonin in frontal cortex

The mixed serotonin and noradrenaline reuptake inhibitor, duloxetine, (5.0 mg/kg, s.c.), increased levels of serotonin (220%), dopamine (180%) and noradrenaline (470%) in individual dialysates of frontal cortex of freely moving rats. Its influence on serotonin, but not dopamine or noradrenaline, levels was enhanced by the 5-HT1A receptor antagonist, WAY 100,635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclo-hexanecarboxamide 3HCl) (0.16 mg kg(-1), s.c). In the forced swimming test, although duloxetine was inactive alone, it dose dependently reduced immobility in the presence of WAY 100,635. Thus, blockade of 5-HT1A (auto)receptors selectively facilitates the influence of duloxetine on serotonin levels in the frontal cortex in rats and, in the forced swimming model, enhances its 'antidepressant' properties in parallel.

S 15535, a novel benzodioxopiperazine ligand of serotonin (5-HT)1A receptors: II. Modulation of hippocampal serotonin release in relation to potential anxiolytic properties

In these studies, we characterized the influence of the novel benzodioxopiperazine serotonin (5-HT)1A ligand, S 15535, on the release of 5-HT in rat hippocampus and compared its potential anxiolytic properties with those of the 5-HT1A receptor partial agonist, buspirone, the 5-HT1A antagonist, WAY 100,635 and the benzodiazepine, diazepam (DZM). (Doses are in milligrams per kilogram s.c., unless otherwise specified.) S 15535 dose-dependently (0.3-3.0) reduced dialysate concentrations of 5-HT in the hippocampus of anesthetized rats. This action of S 15535 (3.0) was blocked by WAY 100,635 (0.3), (-)-penbutolol (2.0) and (-)-tertatolol (8.0), antagonists at 5-HT1A autoreceptors. In rats, fear-induced ultrasonic vocalizations (USVs) were dose-dependently abolished by S 15535 (0.16-2.5 s.c. and 0.63-10.0 p.o.), an action mimicked by buspirone (0.02-2.5) and DZM (0.16-10.0). Further, the action of S 15535 (0.63) was abolished by WAY 100,635 (0.16) and (-)-penbutolol (10.0), which were inactive alone. S 15535 dose-dependently (0.63-10.0 s.c. and 2.5-40.0 p.o.) blocked aggressive encounters in isolated mice; buspirone (0.16-10.0) and, at high doses, DZM (2.5-40.0) were also effective. WAY 100,635 (0.16), which was inactive alone, fully antagonized the antiaggressive actions of S 15535 (2.5). In an elevated plus-maze, neither S 15535 (0.0025-10.0), buspirone (0.0025-10.0) nor WAY 100,635 (0.00063-0.63) significantly increased open-arm entries, whereas they were increased by DZM (0.16-0.63). In the pigeon conflict test, S 15535 (0.04-0.16 i.m.) markedly increased punished responses and only slightly decreased unpunished responses, even at a 64-fold higher dose. In contrast, buspirone (0.16-2.5 i.m.) and DZM (0.04-2.5 i.m.) showed no or a less marked (4-fold) separation between doses increasing punished and decreasing unpunished responses. In the presence of the 5-HT1A antagonist, (-)-alprenolol (10.0 mg/kg i.m.), S 15535 did not increase punished responses. In a Geller conflict paradigm in rats, S 15535 dose dependently (0.3-3.0) increased punished responses, and its action (1.0) was blocked by (-)-penbutolol (8.0). S 15535 (0.63-40.0 s.c. and 2.5-40.0 p.o.) exerted little influence on motor behavior. In conclusion, in line with its net inhibition of serotoninergic transmission by activation of 5-HT1A autoreceptors and blockade of postsynaptic 5-HT1A receptors, S 15535 expresses anxiolytic activity. In addition, it displays antiaggressive (and antidepressant, accompanying paper) properties. Further, S 15535 does not compromise motor behavior at doses over which it expresses its anxiolytic properties. Thus, S 15535 represents a promising candidate for the treatment of anxious states in man.

(1-(2,5-dimethoxy-4 iodophenyl)-2-aminopropane)-induced head-twitches in the rat are mediated by 5-hydroxytryptamine (5-HT) 2A receptors: modulation by novel 5-HT2A/2C antagonists, D1 antagonists and 5-HT1A agonists

In this study, the involvement of serotonergic and dopaminergic receptors in the modulation of the head-twitch (HTW) response to the 5-hydroxytryptamine (5-HT)2A/5-HT2C agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, was characterized in rats using novel and selective ligands at 5-HT2A, 5-HT2C, D1, D2 and 5-HT1A receptors. HTW were dose-dependently inhibited by the 5-HT2A/2C antagonists, ritanserin, metergoline, mesulergine, mianserin, ICI 169,369 and LY 58,537, by the preferential 5-HT2A antagonist, ketanserin and by the novel, selective 5-HT2A antagonist, SR 46349B. A further selective 5-HT2A antagonist, MDL 100,907, very potently abolished HTW (ED50 = 0.005 mg/kg). The order of relative potency correlated highly with their affinity at 5-HT2A (r = 0.83) but not 5-HT2C receptors (r = 0.06). In addition, the novel, selective 5-HT2C antagonist, SB 200,646A, failed to abolish HTW and the 5-HT2C agonists/5-HT2A antagonists, 1-(3-chlorophenyl)piperazine and 1-(3-trifluoromethylphenyl)piperazine, blocked, rather than elicited, HTW. The D1 antagonists, SCH 23390, NNC 112, NNC 756, SCH 39166 and A 69024, in this order of relative potency that correlated with their affinity at D1 receptors (r = 0.98), blocked HTW. The D2 antagonists, raclopride, eticlopride and haloperidol also blocked HTW. The 5-HT1A agonists, S 14671, S 14506, 8-hydroxy-2-(di-n-propylamino)tetralin, buspirone, ipsapirone and (+)-flesinoxan, abolished HTW. The action of 8-hydroxy-2-(di-n-propylamino)tetralin was blocked by (-)-tertatolol (ID50 = 4.5 mg/kg), a novel 5-HT1A receptor antagonist. Similarly, (-)-tertatolol attenuated the action of S 14506 and abolished that of S 14671, buspirone and ipsapirone. A role of postsynaptic 5-HT1A receptors in the action of 5-HT1A agonists was suggested by the finding that parachlorophenylalanine (3 x 300 mg/kg, i.p.), which depleted cerebral pools of 5-HT, did not modify the activity of ipsapirone. The present data demonstrate that 5-HT2A receptors mediate HTW in rats and that both D1 and D2 receptors as well as (postsynaptic) 5-HT1A receptors play a role in their expression.

The potent activity of the 5-HT1A receptor agonists, S 14506 and S 14671, in the rat forced swim test is blocked by novel 5-HT1A receptor antagonists

The high efficacy methoxynaphtylpiperazine 5-HT1A receptor agonists, S 14506 (1-[2-(4-fluorobenzoylamino)ethyl]-4-(7-methoxynaphtyl)piper azine) and S 14671 (1-[2-(2-thenoylamino)ethyl]-4[1-(7-methoxynaphtyl]piperazin e), potently reduced the duration of immobility in the forced swimming test in rats [minimal effective dose (MED): 0.01 mg/kg, s.c., in each case]; in contrast, the prototypic 5-HT1A receptor agonist, 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide], was much less potent (MED: 0.63 mg/kg). The action of S 14671 (0.16 mg/kg) was completely blocked by the potent 5-HT1A receptor antagonist, SDZ 216-525 (4-(4-[4-(1,1,3-trioxo-2H-1,2-benzoisothiazol-2- yl)butyl]-1-piperazinyl)1H-indole-2-carboxylate) (0.63 mg/kg) and by the novel, selective 5-HT1A receptor antagonist, (+)-WAY 100,135 (N-tertiobutyl-3-[4-(2-methoxyphenyl)piperazinylphenyl propanamide): the effect of the latter was expressed dose dependently (Inhibitory Dose50: 35 mg/kg). Similarly, in the presence of (+)-WAY 100,135, S 14506 (0.63 mg/kg) failed to reduce immobility. Pretreatment with parachlorophenylalanine (3 x 300 mg/kg per day, i.p.), which profoundly depleted cerebral pools of 5-HT, modified neither baseline immobility nor the actions of S 14506 and S 14671. It is concluded that S 14506 and S 14671 possess exceptionally potent activity in the forced swimming test and that their actions reflect the activation of postsynaptic 5-HT1A receptors.

5-HT1A receptors and the tail-flick response. VI. Intrinsic alpha 1A-adrenoceptor antagonist properties can mask the actions of 5-HT1A receptor agonists in the spontaneous tail-flick paradigm

In view of the involvement of central alpha 1-adrenoceptors in the expression of 5-HT1A receptor-mediated spontaneous tail-flicks (STFs) in the rat, this study examined whether the putative alpha 1-adrenoceptor antagonist (alpha 1-antagonist) properties of certain 5-HT1A receptor agonists, (+)-flesinoxan and LY 165,163, might modify their behavior in the STF paradigm. Whereas the 5-HT1A receptor agonists 8-OH-DPAT and WY 48,723 dose-dependently elicited STFs, (+)-flesinoxan was only weakly active and LY 165,163 was ineffective. Further, (+)-flesinoxan and LY 165,163 antagonized the induction of STFs by 8-OH-DPAT and WY 48,723. Nevertheless, (+)-flesinoxan and LY 165,163 mimicked 8-OH-DPAT and WY 48,723 in eliciting a pronounced rise in plasma corticosterone and a marked hypothermia: these actions were blocked by the 5-HT1A receptor antagonist, (-)-alprenolol, but they were not affected by the alpha 1-antagonist prazosin. Reflecting its antagonist actions at alpha 1-adrenoceptors, prazosin evoked a pronounced ptosis, an action mimicked by the preferential alpha 1A-antagonists WB 4101, methylurapidil and benoxathian, whereas chlorethylclonidine, which irreversibly inactivates alpha 1B- but not alpha 1A-adrenoceptors, was inactive. Although 8-OH-DPAT and WY 48,723 failed to modify palpebral aperture, (+)-flesinoxan and LY 165,163 provoked a ptosis, suggesting that they possess alpha 1A-antagonist properties. The alpha 1-agonists cirazoline and ST 587 did not elicit STFs alone and failed to modify the induction of STFs by 8-OH-DPAT and WY 48,723. By contrast, they greatly facilitated the ability of both (+)-flesinoxan and LY 165,163 to induce STFs. STFs elicited by (+)-flesinoxan and LY 165,163 in the presence of cirazoline or ST 587 were blocked not only by prazosin but also by (-)-alprenolol, BMY 7378 and S 15535, all of which are antagonists of postsynaptic 5-HT1A receptors. The facilitatory actions of cirazoline and ST 587 were selective in that they did not permit the induction of STFs by agonists at other 5-HT receptor subtypes (5-HT1B, 5-HT1C, 5-HT2 or 5-HT3). In conclusion, in the STF paradigm, the high-efficacy agonist actions of (+)-flesinoxan and LY 165,163 at 5-HT1A receptors are "masked" by their "intrinsic" alpha 1A-antagonist properties, the neutralization of which by alpha 1-agonists reveals the activation of 5-HT1A receptors.