Targeting neurosteroid synthesis as a therapy for schizophrenia-related alterations induced by early psychosocial stress

Background Cogent evidence has shown that schizophrenia vulnerability is enhanced by psychosocial stress in adolescence, yet the underpinnings of this phenomenon remain elusive. One of the animal models that best capture the relationship between juvenile stress and schizophrenia is isolation rearing (IR). This manipulation, which consists in subjecting rats to social isolation from weaning through adulthood, results in neurobehavioral alterations akin to those observed in schizophrenia patients. In particular, IR-subjected rats display a marked reduction of the prepulse inhibition (PPI) of the startle reflex, which are posited to reflect imbalances in dopamine neurotransmission in the nucleus accumbens (NAcc). We recently documented that the key neurosteroidogenic enzyme 5α-reductase (5αR) plays an important role in the dopaminergic regulation of PPI; given that IR leads to a marked down-regulation of this enzyme in the NAcc, the present study was designed to further elucidate the functional role of 5αR in the regulation of PPI of IR-subjected rats. Methods We studied the impact of the prototypical 5αR inhibitor finasteride (FIN) on the PPI deficits and NAcc steroid profile of IR-subjected male rats, in comparison with socially reared (SR) controls. Results FIN (25–100 mg/kg, i.p.) dose-dependently countered IR-induced PPI reduction, without affecting gating integrity in SR rats. The NAcc and striatum of IR-subjected rats displayed several changes in neuroactive steroid profile, including a reduction in pregnenolone in both SR and IR-subjected groups, as well as a decrease in allopregnanolone content in the latter group; both effects were significantly opposed by FIN. Conclusions These results show that 5αR inhibition counters the PPI deficits induced by IR, possibly through limbic changes in pregnenolone and/or allopregnanolone concentrations

Cardiovascular remodelling in female diabetic rats

Diabetic cardiomyopathy involves both cardiac and large vessels alterations in their biochemical and biomechanical properties. Part of these dysfunctions is due to ROS overproduction and advanced glycated end-products (AGEs) synthesis caused by high blood glucose concentrations (1). Epidemiological studies usually ignore sexgender outcomes of diabetes that has higher cardiovascular risk in women than in men (2). The aim of the present study was to assess the effects of diabetes on aorta, portal vein and myocardium morphology in females Wistar rats. Diabetes was induced by a single dose of streptozotocin 65 mg/kg, and, after 4 and half months, we evaluated the cardiovascular remodelling by light and transmission electron microscopy (TEM). Paraformaldehyde fixed samples of aorta and portal vein were stained with Masson Trichrome method (for collagen fibers), Weigert’s stain (for elastic fibers), Hematoxylin and Eosin (for nuclei), and underwent to morphometric analysis. TEM samples were prepared accordingly to common protocols. Morphometric analysis performed on diabetic aortas showed a reduction of tunica media thickness, but the internal diameter width or the lumen cross-area was unchanged compared to controls. The number of smooth muscle cells increased in tunica media of diabetic aortas. The main change observed in diabetic portal veins was a reduction of the area occupied by elastic fibers in tunica adventitia. TEM observations of papillary muscles did not reveal any changes in the sarcomere lengths across the two experimental groups. These results display slight differences on what was reported in male rats (3) and account for a different development of diabetes in female subjects

The aggression and behavioral abnormalities associated with monoamine oxidase A deficiency are rescued by acute inhibition of serotonin reuptake

The termination of serotonin (5-hydroxytryptamine, 5-HT) neurotransmission is regulated by its uptake by the 5-HT transporter (5-HTT), as well as its degradation by monoamine oxidase (MAO)-A. MAO-A deficiency results in a wide set of behavioral alterations, including perseverative behaviors and social deficits. These anomalies are likely related to 5-HTergic homeostatic imbalances; however, the role of 5-HTT in these abnormalities remains unclear. To ascertain the role of 5-HTT in the behavioral anomalies associated to MAO-A deficiency, we tested the behavioral effects of its blocker fluoxetine on perseverative, social and aggressive behaviors in transgenic animals with hypomorphic or null-allele MAO-A mutations. Acute treatment with 5-HTT blocker fluoxetine (10 mg/kg, i.p.) reduced aggressive behavior in MAO-A knockout (KO) mice and social deficits in hypomorphic MAO-ANeo mice. Furthermore, this treatment also reduced perseverative responses (including marble burying and water mist-induced grooming) in both MAO-A mutant genotypes. Both MAO-A mutant lines displayed significant reductions in 5-HTT expression across the prefrontal cortex, amygdala and striatum, as quantified by immunohistochemical detection; however, the down-regulation of 5-HTT in MAO-ANeo mice was more pervasive and widespread than in their KO counterparts, possibly indicating a greater ability of the hypomorphic line to enact compensatory mechanisms with respect to 5-HT homeostasis. Collectively, these findings suggest that the behavioral deficits associated with low MAO-A activity may reflect developmental alterations of 5-HTT within 5-HTergic neurons. Furthermore, the translational implications of our results highlight 5-HT reuptake inhibition as an interesting approach for the control of aggressive outbursts in MAO-A deficient individuals

Enhanced endocannabinoid-mediated modulation of rostromedial tegmental nucleus drive onto dopamine neurons in sardinian alcohol-preferring rats

The progressive predominance of rewarding effects of addictive drugs over their aversive properties likely contributes to the transition from drug use to drug dependence. By inhibiting the activity of DA neurons in the VTA, GABA projections from the rostromedial tegmental nucleus (RMTg) are well suited to shift the balance between drug-induced reward and aversion. Since cannabinoids suppress RMTg inputs to DA cells and CB1 receptors affect alcohol intake in rodents, we hypothesized that the endocannabinoid system, by modulating this pathway, might contribute to alcohol preference. Here we found that RMTg afferents onto VTA DA neurons express CB1 receptors and display a 2-arachidonoylglycerol (2-AG)-dependent form of short-term plasticity, that is, depolarization-induced suppression of inhibition (DSI). Next, we compared rodents with innate opposite alcohol preference, the Sardinian alcohol-preferring (sP) and alcohol-nonpreferring (sNP) rats. We found that DA cells from alcohol-naive sP rats displayed a decreased probability of GABA release and a larger DSI. This difference was due to the rate of 2-AG degradation. In vivo, we found a reduced RMTg-induced inhibition of putative DA neurons in sP rats that negatively correlated with an increased firing. Finally, alcohol failed to enhance RMTg spontaneous activity and to prolong RMTg-induced silencing of putative DA neurons in sP rats. Our results indicate functional modifications of RMTg projections to DA neurons that might impact the reward/aversion balance of alcohol attributes, which may contribute to the innate preference observed in sP rats and to their elevated alcohol intak

Shedding light on typical species : implications for habitat monitoring

Habitat monitoring in Europe is regulated by Article 17 of the Habitats Directive, which suggests the use of typical species to assess habitat conservation status. Yet, the Directive uses the term “typical” species but does not provide a definition, either for its use in reporting or for its use in impact assessments. To address the issue, an online workshop was organized by the Italian Society for Vegetation Science (SISV) to shed light on the diversity of perspectives regarding the different concepts of typical species, and to discuss the possible implications for habitat monitoring. To this aim, we inquired 73 people with a very different degree of expertise in the field of vegetation science by means of a tailored survey composed of six questions. We analysed the data using Pearson's Chi-squared test to verify that the answers diverged from a random distribution and checked the effect of the degree of experience of the surveyees on the results. We found that most of the surveyees agreed on the use of the phytosociological method for habitat monitoring and of the diagnostic and characteristic species to evaluate the structural and functional conservation status of habitats. With this contribution, we shed light on the meaning of “typical” species in the context of habitat monitoring

Cardiovascular remodelling in female diabetic rats

Diabetic cardiomyopathy involves both cardiac and large vessels alterations in their biochemical and biomechanical properties. Part of these dysfunctions is due to ROS overproduction and advanced glycated end-products (AGEs) synthesis caused by high blood glucose concentrations (1). Epidemiological studies usually ignore sexgender outcomes of diabetes that has higher cardiovascular risk in women than in men (2). The aim of the present study was to assess the effects of diabetes on aorta, portal vein and myocardium morphology in females Wistar rats. Diabetes was induced by a single dose of streptozotocin 65 mg/kg, and, after 4 and half months, we evaluated the cardiovascular remodelling by light and transmission electron microscopy (TEM). Paraformaldehyde fixed samples of aorta and portal vein were stained with Masson Trichrome method (for collagen fibers), Weigert’s stain (for elastic fibers), Hematoxylin and Eosin (for nuclei), and underwent to morphometric analysis. TEM samples were prepared accordingly to common protocols. Morphometric analysis performed on diabetic aortas showed a reduction of tunica media thickness, but the internal diameter width or the lumen cross-area was unchanged compared to controls. The number of smooth muscle cells increased in tunica media of diabetic aortas. The main change observed in diabetic portal veins was a reduction of the area occupied by elastic fibers in tunica adventitia. TEM observations of papillary muscles did not reveal any changes in the sarcomere lengths across the two experimental groups. These results display slight differences on what was reported in male rats (3) and account for a different development of diabetes in female subjects

Male and Female Rats Differ in Brain Cannabinoid CB1 Receptor Density and Function and in Behavioural Traits Predisposing To Drug Addiction: Effect of Ovarian Hormones.

Sex-dependent differences are frequently observed in the biological and behavioural effects of substances of abuse, including cannabis. We recently demonstrated a modulating effect of sex and oestrous cycle on cannabinoid-taking and seeking behaviours. Here, we investigated the influence of sex and oestrogen in the regulation of cannabinoid CB1 receptor density and function, measured by [3H]CP55940 and CP55940-stimulated [35S]GTP?S binding autoradiography, respectively, in the prefrontal cortex (Cg1 and Cg3), caudate-putamen, nucleus accumbens, amygdala and hippocampus of male and cycling female rats, as well as ovariectomised (OVX) rats and OVX rats primed with oestradiol (10 μg/rat) (OVX+E). CB1 receptor density was significantly lower in the prefrontal cortex and amygdala of cycling females than in males and in OVX females, a difference that appeared to be oestradiol-dependent, because it was no more evident in the OVX+E group. CP55940-stimulated [35S]GTPαS binding was significantly higher in the Cg3 of OVX rats relative to cycling and OVX+E rats. No difference was observed in CB1 receptor density or function in any of the other brain areas analysed. Finally, sex and oestradiol were also found to affect motor activity, social behaviour and sensorimotor gating in rats tested in locomotor activity boxes, social interaction and prepulse inhibition tasks, respectively. Our findings provide biochemical evidence for sex- and hormone-dependent differences in the density and function of CB1 receptors in selected brain regions, and in behaviours associated with greater vulnerability to drug addiction, revealing a more vulnerable behavioural phenotype in female than in male rats

Effects of SR on nNOS and GFAP-IR in the CPu.

<p>A. Rats received injections of 1/kg Δ9-THC or VEH at 0.5, 12, 24, 36 and 48 h after the last METH administration (Post-treatment, POST) and were sacrificed 3 days after the last METH injection. SR (1 mg/kg, i.p.) or VEH were administered 15 min before each Δ9-THC or VEH injection. Two-way ANOVA in the CPu (A) showed a significant Δ9-THC x SR interaction (F_(1,40) = 32.45, <i>p</i><0.0001); the administration of SR blunted the effect of Δ9-THC on METH-induced nNOS over-expression. SR alone decreased nNOS labeled neurons compared to that of control. ***p<0.001 vs METH-VEH (VEH pretreated) and <b>^##</b>p<0.01 vs METH-VEH-Δ9-THC (VEH pretreated). B. Two-way ANOVA for GFAP-IR revealed a significant interaction between Δ9-THC and SR in the CPu (F_(1,35) = 19.86, <i>p</i><0001). Δ9-THC and SR, alone or in combination, attenuated the METH-induced increase of GFAP-IR in the CPu. ***<i>p</i><0.001 vs METH-VEH (VEH pretreated).</p

Regional distribution of 5α-reductase type 2 in the adult rat brain: An immunohistochemical analysis

The enzyme 5α-reductase (5αR) catalyzes the conversion of testosterone and other Δ4-3-ketosteroids into their 5α-reduced metabolites. Of the five members of the 5αR family, the type 2 enzyme (5αR2) plays a key role in androgen metabolism, and is abundantly distributed in the urogenital system. Although 5αR2 has been reported to be highly expressed in the brain during early developmental stages, little is currently known on its anatomical and cellular distribution in the adult brain. Thus, the present study was designed to determine the detailed localization of 5αR2 in the adult rat brain, using a highly specific polyclonal antibody against this isoform. Parasagittal and coronal sections revealed 5αR2 immunoreactivity throughout most brain regions, with strong immunolabeling in the layers III and VI of the prefrontal and somatosensory cortex, olfactory bulb, thalamic nuclei, CA3 field of hippocampus, basolateral amygdala and Purkinje cell layer of cerebellum. Lower 5αR2 levels were detected in the hypothalamus and midbrain. Moreover, double labeling fluorescence with confocal laser scanning microscopy (CLSM) revealed that 5αR2 is localized in neurons, but not in glial cells. Specifically, the enzyme was documented in the pyramidal neurons of the cortex by CLSM analysis of simultaneous Golgi-Cox and immunofluorescent staining. Finally, low levels of 5αR2 expression were identified in GABAergic cells across the cortex, hippocampus and striatum. These findings show that, in the adult brain, 5αR2 is distributed in critical regions for behavioral regulation, suggesting that the functional role of this isoform is present throughout the entire lifespan of the individual