Neonatal Kisspeptin is Steroid‐Independently Required for Defeminisation and Peripubertal Kisspeptin‐Induced Testosterone is Required for Masculinisation of the Brain: A Behavioural Study Using Kiss1 Knockout Rats

Rodents show apparent sex differences in their sexual behaviours. The present study used Kiss1 knockout (KO) rats to evaluate the role of kisspeptin in the defeminisation/masculinisation of the brain mechanism that controls sexual behaviours. Castrated adult Kiss1 KO males treated with testosterone showed no male sexual behaviours but demonstrated the oestrogen‐induced lordosis behaviours found in wild‐type females. The sizes of some of the sexual dimorphic nuclei of Kiss1 KO male rats are similar to those of females. Plasma testosterone levels at embryonic day 18 and postnatal day 0 (PND0) in Kiss1 KO males were high, similar to wild‐type males, indicating that perinatal testosterone is secreted in a kisspeptin‐independent manner. Long‐term exposure to testosterone from peripubertal to adult periods restored mounts and intromissions in KO males, suggesting that kisspeptin‐dependent peripubertal testosterone secretion is required to masculinise the brain mechanism. This long‐term testosterone treatment failed to abolish lordosis behaviours in KO males, whereas kisspeptin replacement at PND0 reduced lordosis quotients in Kiss1 KO males but not in KO females. These results suggest that kisspeptin itself is required to defeminise behaviour in the perinatal period, in cooperation with testosterone. Oestradiol benzoate treatment at PND0 suppressed lordosis quotients in Kiss1 KO rats, indicating that the mechanisms downstream of oestradiol work properly in the absence of kisspeptin. There was no significant difference in aromatase gene expression in the whole hypothalamus between Kiss1 KO and wild‐type male rats at PND0. Taken together, the present study demonstrates that both perinatal kisspeptin and kisspeptin‐independent testosterone are required for defeminisation of the brain, whereas kisspeptin‐dependent testosterone during peripuberty to adulthood is needed for masculinisation of the brain in male rats.     

Endocrine disruption of gene expression and microRNA profiles in hippocampus and hypothalamus of California mice: Association of gene expression changes with behavioural outcomes

The hypothalamus and hippocampus are sensitive to early exposure to endocrine disrupting chemicals (EDCs). Two EDCs that have raised particular concerns are bisphenol A (BPA), a widely prevalent chemical in many common household items, and genistein (GEN), a phyto‐oestrogen present in soy and other plants. We hypothesised that early exposure to BPA or GEN may lead to permanent effects on gene expression profiles for both coding RNAs (mRNAs) and microRNAs (miRs), which can affect the translation of mRNAs. Such EDC‐induced biomolecular changes may affect behavioural and metabolic patterns. California mice (Peromyscus californicus) male and female offspring were developmentally exposed via the maternal diet to BPA (5 mg kg^‐1 feed weight low dose [LD] and 50 mg kg^‐1 feed weight upper dose [UD]), GEN (250 mg kg^‐1 feed weight) or a phyto‐oestrogen‐free diet (AIN) control. Behavioural and metabolic tests were performed at 180 days of age. A quantitative polymerase chain reacttion analysis was performed for candidate mRNAs and miRs in the hypothalamus and hippocampus. LD BPA and GEN exposed California mice offspring showed socio‐communication impairments. Hypothalamic Avp, Esr1, Kiss1 and Lepr were increased in LD BPA offspring. miR‐153 was elevated but miR‐181a was reduced in LD BPA offspring. miR‐9 and miR‐153 were increased in the hippocampi of LD BPA offspring, whereas GEN decreased hippocampal miR‐7a and miR‐153 expression. Correlation analyses revealed neural expression of miR‐153 and miR‐181a was associated with socio‐communication deficits in LD BPA individuals. The findings reveal a cause for concern such that developmental exposure of BPA or GEN in California mice (and potentially by translation in humans) can lead to long standing neurobehavioural consequences.     

The selective oestrogen receptor modulator,bazedoxifene, mimics the neuroprotective effect of 17β‐oestradiol in diabetic ischaemic stroke by modulating oestrogen receptor expression and the MAPK/ERK1/2 signalling pathway

Because neuroprotection in stroke should be revisited in the era of recanalisation, the present study analysed the potential neuroprotective effect of the selective oestrogen receptor modulator, bazedoxifene acetate (BZA), in an animal model of diabetic ischaemic stroke that mimics thrombectomy combined with adjuvant administration of a putative neuroprotectant. Four weeks after induction of diabetes (40 mg kg^‐1 streptozotocin, i.p.), male Wistar rats were subjected to transient middle cerebral artery occlusion (intraluminal thread technique, 60 minutes) and assigned to one of three groups treated with either: vehicle, BZA (3 mg kg^‐1 day^‐1, i.p.) or 17β‐oestradiol (E₂) (100 μg kg^‐1 day^‐1, i.p.). At 24 hours post‐ischaemia‐reperfusion, brain damage (neurofunctional score, infarct size and apoptosis), expression of oestrogen receptors (ER)α, ERβ and G protein‐coupled oestrogen receptor), and activity of the mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK)1/2 and phosphoinositide 3‐kinase/Akt pathways were analysed. At 24 hours after the ischaemic insult, both BZA‐ and E₂‐treated animals showed lower brain damage in terms of improved neurofunctional condition, decreased infarct size and decreased apoptotic cell death. Ischaemia‐reperfusion induced a significant decrease in ERα and ERβ expression without affecting that of G protein‐coupled oestrogen receptor, whereas BZA and E₂ reversed such a decrease. The ischaemic insult up‐regulated the activity of both the MAPK/ERK1/2 and phosphoinositide 3‐kinase/Akt pathways; BZA and E₂ attenuated the increased activity of the ERK1/2 pathway, without affecting that of the Akt pathway. The results of the present study lend further support to the consideration of BZA as an effective and safer alternative overcoming the drawbacks of E₂ with respect to improving diabetic ischaemic stroke outcome after successful reperfusion.     

Isoallopregnanolone reduces tic‐like behaviours in the D1CT‐7 mouse model of Tourette syndrome

Tourette syndrome (TS) is a neuropsychiatric disorder characterised by multiple, persistent tics. These semi‐voluntary motor and phonic manifestations are typically aggravated by exposure to acute stress, yet the mechanisms underlying this exacerbation remain unclear. Using a well‐characterised animal model of TS, the D1CT‐7 mouse, we recently showed that acute stress increases tic‐like responses and causes sensorimotor gating deficits, as measured by the prepulse inhibition of the startle. We showed that these effects are promoted by the brain synthesis of the neurosteroid allopregnanolone (AP). In line with this idea, inhibition of AP synthesis by finasteride was found to suppress the tic‐exacerbating effects of stress; conversely, AP administration resulted in a marked enhancement of the number of tic‐like motor bursts. Given that the primary mechanism of AP is based on the positive allosteric modulation of GABA_A receptors, in the present study, we hypothesised that the enhancement in tic‐like behaviours induced by either stress or AP may be countered by isoallopregnanolone (isoAP), the natural 3β‐epimer of AP that acts as an antagonist to the AP‐binding site within GABA_A receptors. In agreement with our hypothesis, isoAP (5‐10 mg kg^‐1, s.c.) dose‐dependently reduced the number of tic‐like behaviours induced by stress in D1CT‐7 mice. These effects were comparable to those elicited by both the benchmark TS therapy haloperidol (0.3 mg kg^‐1, i.p.), as well as finasteride (25 mg kg^‐1, i.p.). IsoAP also countered the prepulse inhibition deficits secondary to stress in D1CT‐7 mice. Finally, isoAP opposed the enhancement of tic‐like behaviours induced by AP (15 mg kg^‐1, i.p.). Given that isoAP is well‐tolerated and has an optimal safety profile, these data suggest that this steroid may have therapeutic properties in TS.     

Sexually dimorphic responses of rats to fluoxetine in the forced swimming test are unrelated to the function of the serotonin transporter in the brain

Due to the prevalence of depression in women, female rats may be a better models for antidepressant research than males. In male rats, fluoxetine inhibited the serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) which is reducing the immobility time in the repeated forced swimming test (rFST). The performance of female rats in this test is unknown. In this study, responses of male and female rats in the rFST under chronic treatment with fluoxetine and the function of SERT in their brains were examined. Wistar rats received oral fluoxetine (females: 0, 1, 2.5, or 5 mg kg^-1 day^-1; males: 0 or 2.5 mg kg^-1 day^-1; in sucrose 10%, 1.5 ml/rat) 1 hr before the test daily for 12 days over the course of the rFST. rFST consisted of a 15 min pretest followed by 5 min sessions of swimming at 1 (test), 7 (retest 1), and 14 (retest 2) days later. SERT functioning was assessed by ex vivo assays of the frontal cortex and hippocampus of rats. Fluoxetine reduced immobility time of males in the rFST while it failed to do so in females. In vitro treatment with fluoxetine inhibited the uptake of 5-HT of both sexes similarly, while in vivo chronic administration of fluoxetine failed to do so. In summary, rats responded to the chronic treatment with fluoxetine in a sexually dimorphic fashion during the rFST despite the functioning of SERT in their brains remaining equally unchanged. Hence, our data suggest that sexually dimorphic responses to fluoxetine in rFST may be unrelated to the function of SERT in rat brains.     

Kisspeptin neurones in the posterodorsal medial amygdala modulate sexual partner preference and anxiety in male mice

The posterodorsal medial amygdala (MePD) is a neural site in the limbic brain involved in regulating emotional and sexual behaviours. There is, however, limited information available on the specific neuronal cell type in the MePD functionally mediating these behaviours in rodents. The recent discovery of a significant kisspeptin neurone population in the MePD has raised interest in the possible role of kisspeptin and its cognate receptor in sexual behaviour. The present study therefore tested the hypothesis that the MePD kisspeptin neurone population is involved in regulating attraction towards opposite sex conspecifics, sexual behaviour, social interaction and the anxiety response by selectively stimulating these neurones using the novel pharmacosynthetic DREADDs (designer receptors exclusively activated by designer drugs) technique. Adult male Kiss‐Cre mice received bilateral stereotaxic injections of a stimulatory DREADD viral construct (AAV‐hSyn‐DIO‐hM₃D(Gq)‐mCherry) targeted to the MePD, with subsequent activation by i.p. injection of clozapine‐N‐oxide (CNO). Socio‐sexual behaviours were assessed in a counter‐balanced fashion after i.p. injection of either saline or CNO (5 mg kg^‐1). Selective activation of MePD kisspeptin neurones by CNO significantly increased the time spent by male mice in investigating an oestrous female, as well as the duration of social interaction. Additionally, after CNO injection, the mice appeared less anxious, as indicated by a longer exploratory time in the open arms of the elevated plus maze. However, levels of copulatory behaviour were comparable between CNO and saline‐treated controls. These data indicate that DREADD‐induced activation of MePD kisspeptin neurones enhances both sexual partner preference in males and social interaction and also decreases anxiety, suggesting a key role played by MePD kisspeptin in sexual motivation and social behaviour.     

Glyphosate and glyphosate‐based herbicide exposure during the peripartum period affects maternal brain plasticity,maternal behaviour and microbiome

Glyphosate is found in a large array of non‐selective herbicides such as Roundup® (Monsanto, Creve Coeur, MO, USA) and is by far the most widely used herbicide. Recent work in rodent models suggests that glyphosate‐based herbicides during development can affect neuronal communication and result in altered behaviours, albeit through undefined mechanisms of action. To our knowledge, no study has investigated the effects glyphosate or its formulation in herbicide on maternal behaviour and physiology. In the present study, relatively low doses of glyphosate (5 mg kg^‐1 d^‐1), Roundup® (5 mg kg^‐1 d^‐1 glyphosate equivalent), or vehicle were administered by ingestion to Sprague‐Dawley rats from gestational day (GD) 10 to postpartum day (PD)22. The treatments significantly altered licking behaviour toward pups between PD2 and PD6. We also show in the dams at PD22 that Roundup exposure affected the maturation of doublecortin‐immunoreactive new neurones in the dorsal dentate gyrus of the hippocampus of the mother. In addition, the expression of synaptophysin was up‐regulated by glyphosate in the dorsal and ventral dentate gyrus and CA3 regions of the hippocampus, and down‐regulated in the cingulate gyrus. Although a direct effect of glyphosate alone or its formulation on the central nervous system is currently not clear, we show that gut microbiota is significantly altered by the exposure to the pesticides, with significant alteration of the phyla Bacteroidetes and Firmicutes. This is the first study to provide evidence that glyphosate alone or in formulation (Roundup) differentially affects maternal behaviour and modulates neuroplasticity and gut microbiota in the mother.     

Effects of salt‐loading on supraoptic vasopressin neurones assessed by ClopHensorN chloride imaging

Salt‐loading (SL) impairs GABA_A inhibition of arginine vasopressin (AVP) neurones in the supraoptic nucleus (SON) of the hypothalamus. Based on previous studies, we hypothesised that SL activates tyrosine receptor kinase B (TrkB), down‐regulating the activity of K⁺/Cl^? co‐transporter2 (KCC2) and up‐regulating Na⁺/K⁺/Cl^? co‐transporter1 (NKCC1). These changes in chloride transport would result in increased [Cl^?]_i in SON AVP neurones. The study combined virally‐mediated chloride imaging with ClopHensorN with a single‐cell western blot analysis. An adeno‐associated virus with ClopHensorN and a vasopressin promoter (AAV2‐0VP1‐ClopHensorN) was bilaterally injected in the SON of adult male Sprague‐Dawley rats that were either euhydrated (Eu) or salt‐loaded (SL) for 7 days. Acutely dissociated SON neurones expressing ClopHensorN were tested for decreases or increases in [Cl^?]_i in response to focal application of the GABA_A agonist muscimol (100 μmol L^‐1). SON AVP neurones from Eu rats showed muscimol‐induced chloride influx (P < 0.05;23/35). SON AVP neurones from SL rats either significantly increased chloride efflux (P < 0.05;27/39) or did not change chloride flux (12/39). The SON AVP neurones that responded to muscimol appeared to be viable and expressed KCC2 and β‐actin. Neurones that did not respond during chloride imaging did not show KCC2 and β‐actin protein expression. The KCC2 antagonist (VU0240551,10 μmol L^‐1) significantly blocked the chloride influx in cells from Eu rats but did not affect cells from SL rats. A NKCC1 antagonist (bumetanide,10 μmol L^‐1) significantly blocked the chloride efflux in cells from SL rats but had no effect on cells from Eu rats. Blocking NKCC1 using bumetanide had less of an effect on the muscimol‐induced Cl^? influx in Eu rat neurones compared to the KCC2 antagonist. The TrkB antagonist (AnA‐12) (50 μmol L^‐1) and protein kinase inhibitor (K252a) (100 nmol L^‐1) each significantly blocked chloride efflux in SON AVP neurones from SL rats. Salt‐loading increases [Cl^?]_i in SON AVP neurones via a TrKB‐KCC2‐NKCC1‐dependent mechanism in rats.     

Voltammetric Bioassay of Caffeine using Sensor Implant

In this article, we examined the performance of the voltammetric assay of caffeine using DNA immobilized onto a carbon nanotube paste electrode (DPE) and compared it with that of an ordinary carbon nanotube paste electrode (PE). Under optimal conditions, the working ranges for caffeine were from 0.1 to 12 mg l⁻¹ (for DPE) and 30–230 mg l⁻¹ (for PE). Detection limits (DLs) of 0.068 mg l⁻¹ (3.50 × 10⁻⁷ M) DPE and 9.94 mg l⁻¹ (5.12×10⁻⁵ M) PE were obtained and the relative standard deviation at the caffeine concentration of 5.0 mg l⁻¹ was 0.064% (n = 15) DPE under optimum conditions. The sensor could be implanted in a leaf skin or animal brain cell, which can then be interfaced with an electrochemical workstation. It can be used in real-time in vivo caffeine analysis in a live cell or leaf skin.     

Prenatal exposure to perfluorooctanesulfonate in rat resulted in long‐lasting changes of expression of synapsins and synaptophysin

Both animal and human studies have demonstrated that exposure to chemical pollutants during critical developmental period causes adverse consequences later in life. In uterus, perfluorooctanesulfonate (PFOS) exposure has been known to cause developmental neurotoxicity, such as increased motor activity, reduced habitation and impaired cognitive function. The possible mechanism of the impaired cognitive function induced by prenatal PFOS exposure was evaluated in this study. Pregnant Sprague Dawley (SD) rats were given 0.1, 0.6, and 2.0 mg kg^?1 birth weight (bw) d^?1 by gavage from gestation day (GD) 0 to GD20. Control received 0.5% Tween‐20 vehicle (4 ml kg^?1 bw d^?1). PFOS concentration in hippocampus of offspring was observed on postnatal day (PND) 0 and PND21. The ultrastructure of hippocampus and the gene expression of synaptic vesicle associated proteins in offspring hippocampus, which were important for the neurotransmitter release, were investigated. The transmission electron photomicrographs of the offspring hippocampus from PFOS‐treated maternal groups showed the ultrastructure of synapses was negatively affected. The offspring from PFOS‐treated maternal groups also differed significantly from controls with respect to the expression of synaptic vesicle associated proteins. The mRNA levels of synapsin1 (Syn1), synapsin2 (Syn2), and synaptophysin (Syp) were decreased in treated groups either on PND0 or on PND21. However, the mRNA level of synapsin3 (Syn3) decreased in 0.6‐ and 2.0‐mg kg^?1 group on PND0, and showed no significant difference among control group and all treated groups on PND21. These results indicate that the impairment of cognitive function induced by PFOS may be attributed to the lower mRNA levels of synaptic vesicle associated proteins and the change of synaptic ultrastructure in hippocampus. Synapse, 2010. © 2010 Wiley‐Liss, Inc.     

Adolescent escitalopram prevents the effects of maternal separation on depression- and anxiety-like behaviours and regulates the levels of inflammatory cytokines in adult male mice

There is little research on the effects of adolescent administration of antidepressants on behavioural function and inflammation in early-life stressed adult mice. Using maternal separation (MS), a paradigm of early adversity, we investigated the effects of adolescent (PND 33-54) escitalopram (ES; 10 mg/kg) exposure on depression- and anxiety-like behaviours and the levels of inflammatory cytokines (interleukin [IL]-1β, tumor necrosis factor [TNF]-α, and IL-10) in the ventral hippocampus (HPV), prefrontal cortex (PFC), and serum in adult (PND 61) male offspring mice. The results showed that MS has no effect on locomotor activity, but increased depression-like behaviours in the saccharin preference test and increased anxiety-like behaviours in the social preference and elevated plus maze tests. MS increased the levels of IL-1β in the HPV, PFC, and serum, while decreasing the level of IL-10 in the HPV. Furthermore, adolescent ES treatment inhibited these depression- and anxiety-like behaviours, decreased the levels of IL-1β, and increased the level of IL-10 in the HPV. The results also showed that there are no effects of chronic escitalopram administration on normal behaviour in control mice. Taken together, the current data provide experimental evidence that MS increases depression and anxiety levels in adult male offspring. Additionally, the findings support the idea that early pharmacological intervention with ES may be an effective treatment for reducing the behavioral abnormalities induced by early adversity and regulating the underlying inflammatory mechanisms involved.     

Sex‐specific expression of estrogen receptors α and β and Kiss1 in the postnatal rat amygdala

The rodent amygdaloid complex is composed of numerous subnuclei important for the sex‐specific regulation of sociosexual behavior. Although estrogen receptors (ERs) are critical for organizing functional and cytoarchitectural sex differences in these subnuclei, a detailed developmental profile of ER expression in the amygdaloid complex is not available. Moreover, the kisspeptin gene (Kiss1) was recently identified in the adult amygdala, but it remains unknown if it is expressed during development. To fill these data gaps, rat brains (5–7/group) were assessed on postnatal days (PNDs) 0, 2, 4, 7, and 19 for ER alpha (ERα; Esr1), beta (ERβ; Esr2), and Kiss1 expression using in situ hybridization. Expression was quantified in the posterodorsal portion of the medial amygdala posterodorsal (MePD), lateral (PLCo), and medial (PMCo) components of the posterior cortical nucleus, and the amygdalohippocampal area (AHi). ERα expression was high throughout the amygdala at birth, but sexually dimorphic only in the AHi. ERα expression in the MePD and the PLCo showed a U‐shaped expression pattern over time. In the PMCo, ERα expression decreased from PND 2 and remained low through PND 19. Sexually dimorphic expression of ERβ in the MePD was observed on PND 0, with higher levels in females, but reversed by PND 4 due to declining levels in females. No Kiss1 signal was observed in the postnatal amygdala, suggesting that expression arises after puberty. These data reveal that ER expression is region‐specific within the neonatal amygdala. These differences likely contribute to sex differences in sociosexual behavior across the lifespan. J. Comp. Neurol. 521:465–478, 2013. © 2012 Wiley Periodicals, Inc.     

MicroPET imaging of ketamine-induced neuronal apoptosis with radiolabeled DFNSH

Recent reports indicate that 6–12 h of ketamine anesthesia can trigger neuronal apoptosis in postnatal day (PND) 7 rats. In vitro, ex vivo, and confocal fluorescent imaging studies suggest that dansyl compounds can accumulate within the cytoplasm of the apoptotic cell. High-resolution positron emission tomography (microPET) imaging has been proposed as a minimally invasive method for detecting apoptosis in the rat brain. Compared with [¹⁸F]-labeled annexin V, which binds to externalized phosphatidylserine (PS) on the outer membrane of apoptotic cells, intracellular uptake of the dansylhydrazone of p-fluorobenzaldehyde (DFNSH) may lead to improved target-to-background contrast ratios. In this study, the effect of ketamine on the uptake and retention of [¹⁸F]-DFNSH in the rat brain was investigated using microPET imaging. On PND 7, rat pups in the experimental group were exposed, at 2-h intervals, to six subcutaneous injections of ketamine (20 mg/kg) and control rat pups received six injections of saline. On PND 35, [¹⁸F]-DFNSH (37 MBq) was injected into the tail vein of rats and microPET images were obtained over 2 h following the injection. Radiolabeled tracer accumulation in the region of interest (ROI) in the frontal cortex was converted into standard uptake values (SUVs). The radiotracer was quickly distributed into the brains of both ketamine- and saline-treated rats. Compared with the control group, the uptake of [¹⁸F]-DFNSH was significantly increased in the ROI, frontal cortex area of ketamine-treated rats. In addition, the wash-out duration of the tracer was prolonged in the ketamine-treated animals. This study demonstrates that microPET imaging is capable of distinguishing differences in retention of [¹⁸F]-DFNSH in ROI and suggests that this compound may serve as a minimally invasive biomarker of neuronal apoptosis in rodents.     

Dietary selenium addition improves cerebrum and cerebellum impairments induced by methimazole in suckling rats

The aim of this study is to investigate the improving effects of selenium (Se) on cerebrum and cerebellum impairments induced by methimazole (MMI) in suckling rats. Animals were randomly divided into four groups of six each: group I served as control which received standard diet; group II received only MMI (250 mg L⁻¹_, orally); group III received both MMI (250 mg L⁻¹, orally) and Se (0.5 mg kg⁻¹ of diet); group IV served as a positive control and received Se (0.5 mg kg⁻¹ of diet) as sodium selenite (Na₂SeO₃). Treatments were started from the 14th day of pregnancy until day 14 after delivery. In the MMI-treated group, plasma-free thyroid hormone levels (FT₃ and FT₄), protein, DNA and RNA contents in cerebrum and cerebellum decreased when compared to control. Co-treatment with Se ameliorated these parameters. In the MMI-treated group, antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) significantly decreased, while malonaldialdehyde (MDA) levels in cerebrum and cerebellum increased. Co-administration of Se through the diet restored these parameters to near normal values. The biochemical modifications are correlated histologically with the abnormal development of an external granular layer, indicating a delay of granular cells migration towards the molecular layer in the MMI-treated group. Our results showed that Se improved cerebrum and cerebellum MMI-induced damages in suckling rats. Moreover, we concluded that Se is an important neuroprotective element that may be used as a dietary supplement against brain impairments.     

A rat model of pre-puberty (Juvenile) stress-induced predisposition to stress-related disorders: Sex similarities and sex differences in effects and symptoms

Objectives. This study assessed the interactive effect of two risk factors: “Juvenile stress” and sex in the long-term consequences of “Juvenile stress” in male and female rats. Methods. Rats were exposed to “Juvenile stress” and to additional stress in adulthood. Measurements of anxiety and depressive-like behaviours were assessed in relation to each stress exposure and “Sex-specific” sets of criteria in order to characterize individual profiles of altered behaviours. Results. While both male and female rats were affected by exposure to “Juvenile stress”, sex difference were evident in saccharine preference, coping with the stressful challenge of the two-way shuttle avoidance task, and on “Adult stress” induced changes in saccharine preference. “Profiling” altered behaviours revealed sex differences also in the prevalence of rats exhibiting different categories of “Affected” behaviours, indicating that female rats are more susceptible to the long-term effects of “Juvenile stress” and to the immediate effects of “Adulthood stress”. Additionally, the prevalence of “Affected” animals among “Juvenile+ Adulthood stress” was similar, yet the profile of altered behaviours was significantly different. Conclusions. The “Behavioural Profiling” approach presented here is of importance to understanding gender differences in the aetiology of predisposition to stress-related disorders, and of gender symptomatology differences in stress-related disorders.     

Role of the metabotropic glutamate receptor subtype 1 in the Harmaline-induced tremor in rats

The present study shows that JNJ 16259685—a selective antagonist of glutamate metabotropic receptor subtype 1 (mGluR1) injected in doses of 0.16 and 0.32 mg/kg sc strongly enhances tremor of forelimbs, head and trunk, hypolocomotion, and ataxia induced by harmaline (7.5 mg/kg ip) in rats. JNJ 16259685 inhibited locomotor and exploratory activity per se. These results may suggest an inhibitory influence of mGluR1 on the harmaline-induced motor disturbances.     

Leisure activity preferences for 6‐ to 12‐year‐old children with cerebral palsy

Aim The objective was to describe leisure activity preferences of children with cerebral palsy (CP) and their relationship to participation. Factors associated with greater interest in leisure activities were identified. Method Fifty‐five school‐aged children (36 males, 19 females; mean age 9y 11mo; range 6y 1mo–12y 11mo) with CP (Gross Motor Function Classification System [GMFCS]) level I 62%, level II 22%, level III–IV 16%; 33.3% hemiplegia, 29.6% diplegia, 25.9% quadriplegia, 11.2% other) who could complete the Preferences for Activities of Children (PAC) were recruited. Results Social and recreational activities were most preferred, and self‐improvement activities were least preferred. Younger age, higher motivation, and IQ predicted interest in active–physical activities (r²=0.39). Negative reaction to failure was associated with less preference for social activities (r²=0.16), whereas increased prosocial behaviours were related to greater preference for recreational (r²=0.13) and self‐improvement activities; the latter is also predicted by older age (r²=0.24). Interest in skill‐based activities was greater in females and in children who were highly motivated, younger, and had greater motor limitations (r²=0.51). The findings suggest that personal factors and functional abilities influence leisure activity preferences. High preference for certain activities was not always associated with involvement in these activities. Interpretation Determination of preferences is inherent to child‐centred practice and should, therefore, be part of the evaluation process. Rehabilitation strategies can minimize barriers to leisure participation, such as fear of failure, low motivation, or environmental obstacles.     

Impact of early life stress on alcohol consumption and on the short- and long-term responses to alcohol in adolescent female rats

We examined the interaction between early life stress and vulnerability to alcohol in female rats exposed to prenatal restraint stress (PRS rats). First we studied the impact of PRS on ethanol preference during adolescence. PRS slightly increased ethanol preference per se, but abolished the effect of social isolation on ethanol preference. We then studied the impact of PRS on short- and long-term responses to ethanol focusing on behavioral and neurochemical parameters related to depression/anxiety. PRS or unstressed adolescent female rats received 10% ethanol in the drinking water for 4 weeks from PND30 to PND60. At PND60, the immobility time in the forced-swim test did not differ between PRS and unstressed rats receiving water alone. Ethanol consumption had no effect in unstressed rats, but significantly reduced the immobility time in PRS rats. In contrast, a marked increase in the immobility time was seen after 5 weeks of ethanol withdrawal only in unstressed rats. Hippocampal levels of neuropeptide Y (NPY) and mGlu1a metabotropic glutamate receptors were increased at the end of ethanol treatment only in unstressed rats. Ethanol treatment had no effect on levels of corticotropin-releasing hormone (CRH) in the hippocampus, striatum, and prefrontal cortex of both groups of rats. After ethanol withdrawal, hippocampal levels of mGlu1 receptors were higher in unstressed rats, but lower in PRS rats, whereas NPY and CRH levels were similar in the two groups of rats. These data indicate that early life stress has a strong impact on the vulnerability and responsiveness to ethanol consumption during adolescence.     

Detecting neuroinflammation in the brain following chronic alcohol exposure in rats: A comparison between in vivo and in vitro TSPO radioligand binding

Excessive alcohol consumption is associated with neuroinflammation, which likely contributes to alcohol‐related pathology. However, positron emission tomography (PET) studies using radioligands for the 18‐kDa translocator protein (TSPO), which is considered a biomarker of neuroinflammation, reported decreased binding in alcohol use disorder (AUD) participants compared to controls. In contrast, autoradiographic findings in alcohol exposed rats reported increases in TSPO radioligand binding. To assess if these discrepancies reflected differences between in vitro and in vivo methodologies, we compared in vitro autoradiography (using [³H]PBR28 and [³H]PK11195) with in vivo PET (using [¹¹C]PBR28) in male, Wistar rats exposed to chronic alcohol‐vapor (dependent n = 10) and in rats exposed to air‐vapor (nondependent n = 10). PET scans were obtained with [¹¹C]PBR28, after which rats were euthanized and the brains were harvested for autoradiography with [³H]PBR28 and [³H]PK11195 (n = 7 dependent and n = 7 nondependent), and binding quantified in hippocampus, thalamus, and parietal cortex. Autoradiography revealed significantly higher binding in alcohol‐dependent rats for both radioligands in thalamus and hippocampus (trend level for [³H]PBR28) compared to nondependent rats, and these group differences were stronger for [³H]PK11195 than [³H]PBR28. In contrast, PET measures obtained in the same rats showed no group difference in [¹¹C]PBR28 binding. Our in vitro data are consistent with neuroinflammation associated with chronic alcohol exposure. Failure to observe similar increases in [¹¹C]PBR28 binding in vivo suggests the possibility that a mechanism mediated by chronic alcohol exposure interferes with [¹¹C]PBR28 binding to TSPO in vivo. These data question the sensitivity of PBR28 PET as a methodology to assess neuroinflammation in AUD.     

Early life diets with prebiotics and bioactive milk fractions attenuate the impact of stress on learned helplessness behaviours and alter gene expression within neural circuits important for stress resistance

Manipulating gut microbes may improve mental health. Prebiotics are indigestible compounds that increase the growth and activity of health‐promoting microorganisms, yet few studies have examined how prebiotics affect CNS function. Using an acute inescapable stressor known to produce learned helplessness behaviours such as failure to escape and exaggerated fear, we tested whether early life supplementation of a blend of two prebiotics, galactooligosaccharide (GOS) and polydextrose (PDX), and the glycoprotein lactoferrin (LAC) would attenuate behavioural and biological responses to stress later in life. Juvenile, male F344 rats were fed diets containing either GOS and PDX alone, LAC alone, or GOS, PDX and LAC. All diets altered gut bacteria, while diets containing GOS and PDX increased Lactobacillus spp. After 4 weeks, rats were exposed to inescapable stress, and either immediately killed for blood and tissues, or assessed for learned helplessness 24 h later. Diets did not attenuate stress effects on spleen weight, corticosterone and blood glucose; however, all diets differentially attenuated stress‐induced learned helplessness. Notably, in situ hybridization revealed that all diets reduced stress‐evoked cfos mRNA in the dorsal raphe nucleus (DRN), a structure important for learned helplessness behaviours. In addition, GOS, PDX and LAC diet attenuated stress‐evoked decreases in mRNA for the 5‐HT_1A autoreceptor in the DRN and increased basal BDNF mRNA within the prefrontal cortex. These data suggest early life diets containing prebiotics and/or LAC promote behavioural stress resistance and uniquely modulate gene expression in corresponding circuits.