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Objectives: Addresses the role that psychological distress (ie depression and anxiety) plays in mediating the relationship between workplace harassment (ie sexual and generalized workplace harassment) and increased alcohol problems among employed college students., Participants: Two waves of data were collected from 905 study participants sampled from eight colleges and universities in the Midwestern United States., Methods: A mediation analysis was conducted using Hayes's PROCESS macro with bootstrapping., Results: The findings indicated that that workplace harassment predicts increased alcohol problems, and that the association between harassment and alcohol problems is mediated by psychological distress., Conclusions: Workplace harassment is a prevalent problem associated with increased alcohol problems and poor mental health for both genders in the U.S. collegiate workforce. Mental health practitioners and counselors at colleges can help students identify such issues and determine which steps a student might take to address them.

The study examined the relationship between perfectionism (categorized by adaptive, maladaptive, and non-perfectionist clusters), substance use (i.e., drinking and smoking), and mental health in a large sample of college student ( N  = 841; M  = 19.6 years of age) in a time-lagged design. Students were classified using a two-step cluster analysis where subscales are used in hierarchical and k -means cluster analysis. Results revealed that adaptive perfectionists reported better mental health compared to non-perfectionists and maladaptive perfectionists. Additionally, adaptive perfectionists reported lower levels of alcohol use compared to non-perfectionists. Differences between mental health and alcohol use by cluster were found over time, but not for smoking behaviors. Across all participants, substance use did not mediate the relationship between perfectionism and mental health. Future research directions as well as practical implications are discussed.

Food intake and body weight are tightly regulated by neurons within specific brain regions, including the brainstem, where acute activation of dorsal raphe nucleus (DRN) glutamatergic neurons expressing the glutamate transporter Vglut3 (DRN Vglut3 ) drive a robust suppression of food intake and enhance locomotion. Activating Vglut3 neurons in DRN suppresses food intake and increases locomotion, suggesting that modulating the activity of these neurons might alter body weight. Here, we show that DRN Vglut3 neurons project to the lateral hypothalamus (LHA), a canonical feeding center that also reduces food intake. Moreover, chronic DRN Vglut3 activation reduces weight in both leptin-deficient (ob/ob) and leptin-resistant diet-induced obese (DIO) male mice. Molecular profiling revealed that the orexin 1 receptor (Hcrtr1) is highly enriched in DRN Vglut3 neurons, with limited expression elsewhere in the brain. Finally, an orally bioavailable, highly selective Hcrtr1 antagonist (CVN45502) significantly reduces feeding and body weight in DIO. Hcrtr1 is also co-expressed with Vglut3 in the human DRN, suggesting that there might be a similar effect in human. These results identify a potential therapy for obesity by targeting DRN Vglut3 neurons while also establishing a general strategy for developing drugs for central nervous system disorders., (© 2022. The Author(s).)

Employees who feel the urge and preoccupation to respond to workplace asynchronous communication quickly may be suffering from workplace telepressure (WPT). Although information and communication technologies have many organizational benefits, it is imperative to understand the cost of blurring work and family roles. Using the Job Demands-Resources model, the relationship between WPT and key outcomes, such as strain, work-family conflict, family-work conflict (FWC), and burnout was examined. In Study 1, a sample of 220 working students supported the mediation of strain in the WPT and work-family and family-work relationship. Additionally, Study 2 expanded this model using a sample of 269 working individuals. Specifically, the relationship between WPT and burnout was sequentially mediated by strain and either work-family or FWC. Implications are discussed., (© 2021 John Wiley & Sons Ltd.)

The pace of scientific progress over the past several decades within the biological, drug development, and the digital realm has been remarkable. The'omics revolution has enabled a better understanding of the biological basis of disease, unlocking the possibility of new products such as gene and cell therapies which offer novel patient centric solutions. Innovative approaches to clinical trial designs promise greater efficiency, and in recent years, scientific collaborations, and consortia have been developing novel approaches to leverage new sources of evidence such as real-world data, patient experience data, and biomarker data. Alongside this there have been great strides in digital innovation. Cloud computing has become mainstream and the internet of things and blockchain technology have become a reality. These examples of transformation stand in sharp contrast to the current inefficient approach for regulatory submission, review, and approval of medicinal products. This process has not fundamentally changed since the beginning of medicine regulation in the late 1960s. Fortunately, progressive initiatives are emerging that will enrich and streamline regulatory decision making and deliver patient centric therapies, if they are successful in transforming the current transactional construct and harnessing scientific and technological advances. Such a radical transformation will not be simple for both regulatory authorities and company sponsors, nor will progress be linear. We examine the shortcomings of the current system with its entrenched and variable business processes, offer examples of progress as catalysts for change, and make the case for a new cloud based model. To optimize navigation toward this reality we identify implications and regulatory design questions which must be addressed. We conclude that a new model is possible and is slowly emerging through cumulative change initiatives that question, challenge, and redesign best practices, roles, and responsibilities, and that this must be combined with adaptation of behaviors and acquisition of new skills., Competing Interests: All authors are employees and shareholders in the pharmaceutical company Pfizer., (Copyright © 2021 Macdonald, Isom, Evans and Page.)

Caregivers are responsible for the care of another, such as a young adult, disabled child, elderly parent, or sick spouse. Individuals who have caregiving responsibilities must blend the often-contradictory behavioral expectations from the different roles in which they reside. Building on the theoretical foundations of Conservation of Resources theory, this study tests a mediational model explicating the process through which caregiver burden impacts mental health through work-family conflict among a community sample of 1,007 unpaid caregivers in the greater Chicago area who responded to a mail survey at three time points. Structural equation modeling analyses indicate strain-based conflict as being a consistent mediator between caregiver burden and mental health at baseline and two years later. These findings can inform practice and policy for workers with caregiving responsibilities.

Although the caregiver literature has explored a wide array of different variables, there is a gap in research on how demographics of the care recipient affect their caregiver. Using data from a diverse sample of 1,007 unpaid caregivers, individuals were separated into four groups based on care recipient age; childcare, adultcare, eldercare, and those with care recipients from multiple age categories. Then, following previous literature, childcare was split into four groups based on the age of the youngest child cared for (0-2 years; 3-5 years; 6-12 years; and 13-17 years). Group differences were found in work-family conflict (time) and five types of caregiver burden. Specifically, time-dependence burden differed most between groups with caregivers of children (0-2 years) having the highest levels and caregivers of children (13-17) having the lowest levels. There were no differences found between groups for job satisfaction, turnover intentions, or family-work conflict. Additional differences were found when considering caregivers' gender. This research is an exploratory step in understanding how age of care recipient relates to different outcomes for caregivers. Implications are discussed., Competing Interests: There is no conflict of interest for any of the authors.

An important gap in work-family literature is the understanding of how socio-demographic variables, such as sex, age, hours worked, age of youngest child, and household income may relate to work-family conflict. Using data from 667 individuals and longitudinal data from 1,007 caregivers, separate exploratory cluster analysis by gender provided a three cluster solution for caregiving men, non-caregiving men, and caregiving women and a four cluster solution for non-caregiving women. Differences in work interfering with family were found in the caregiving men, caregiving women, and non-caregiving women clusters. Non-caregiving men, non-caregiving women, and caregiving women had differential levels of family interfering with work by cluster. Cohen's D revealed that age had the largest effect size between clusters for individuals and caregivers. Findings and implications are discussed.

Prostate cancer is the most common cancer and the second leading cause of cancer deaths among males in most Western countries. Autologous cellular immunotherapy for the treatment of cancer seeks to induce tumor-specific immunity in the patient and is consequently dependent on a suitable target antigen and effective presentation of that antigen to the patient's immune system. Prostatic acid phosphatase (PAP) has been tested as a target antigen due to its high and apparently specific expression in the prostate. We used a variety of approaches to analyze PAP expression, including immunohistochemistry, in situ hybridization, and quantitative polymerase chain reaction. We complemented these laboratory-based techniques with an in silico analysis of reported PAP expression in human cDNA libraries. Our studies confirmed that, while PAP expression is not restricted to prostate tissues, its expression in other human tissues is approximately 1-2 orders of magnitude less than that observed in the prostate. The relative specificity of PAP expression in the prostate supports its use as a target of autologous cellular immunotherapy. The approach described here, involving the use of multiple correlates of tissue-specific expression, is warranted as a prerequisite in selecting any suitable target for immunotherapy.

The physiological role of the duodenal peptide secretin is as a potent stimulant of electrolyte and water movement in pancreatic and biliary epithelium, via activation of G protein-coupled secretin receptors (hSCTR). However, the distribution and potential function of hSCTR in human lung has not previously been addressed. Using real-time quantitative reverse transcriptase-polymerase chain reaction profiling, in situ hybridization, and immunohistochemistry, we demonstrated that the hSCTR is abundantly expressed within the distal regions of human lung (tertiary bronchus and parenchyma), with negligible expression detected in more proximal regions (trachea, primary, and secondary bronchus). Expression was observed predominantly on the basolateral membrane of the bronchial epithelial layer, with some expression also observed in bronchial smooth muscle. In primary cultures of human tertiary bronchial epithelial cells, secretin was demonstrated to potently stimulate channel-mediated Cl- efflux in a concentration-dependent manner. Secretin was also shown to cause concentration-dependent relaxation of human tertiary bronchial smooth muscle. In summary, these data demonstrate that secretin receptors are present in human lung, and that activation of these receptors with human secretin potently stimulates concentration-dependent Cl- efflux from bronchial epithelial cells and bronchorelaxation.

Malonate is an inhibitor of cellular metabolism, which, following intrastriatal injection, induces a striatal pathology similar to that seen in Huntington's disease. In two parallel studies, we have investigated the suggested relationship between the neuronal vulnerability to metabolic toxicity and the decline in metabolic function with increasing age. The first experiment investigated malonate-induced neuronal loss in animals aged from 6 weeks up to 27 months, and the second assessed the activities of two mitochondrial enzymes, succinate dehydrogenase and cytochrome oxidase (CYTOX) in animals aged 6 weeks, 3, 8 and 18 months. In the first study, male Lister-Hooded rats received intrastriatal stereotaxic injections of malonate (0.5 or 1.0 M). Animals were killed 10 days after surgery, and the brains were stained with cresyl violet and processed for NADPH-diaphorase activity and glial fibrillary-acidic-protein (GFAP) immunohistochemistry. Animals aged 6 months and older exhibited over 60% striatal neuronal loss. However, the degree of neuronal loss did not show any age-related increase in rats between 6 and 27 months of age, indicating that the extent of malonate-induced toxicity does not increase with age in animals older than 6 months. Infusion of 0.5 M malonate produced smaller lesions, which also demonstrated a consistent extent of neuronal loss from 6 months onwards. Metabolic enzyme activities were decreased in the striatum with increasing age, although this effect was only significant for CYTOX activity. Thus, the pattern of malonate-induced neuronal loss in aged animals partially reflects the changes in metabolic activity during ageing.

It has been demonstrated that withdrawal from chronic treatment with haloperidol is associated with a long-lasting increase in the number of striatal dopamine D(2) receptors and variable changes in D(1) receptors. We have investigated the effect of withdrawal from sub-chronic administration of haloperidol on the density of dopamine receptors, dopamine receptor gene expression, and spontaneous locomotor activity. Following a 3-week treatment period with haloperidol (1.5 mg/kg, i.p.), spontaneous locomotor activity measurements, autoradiography of D(1) and D(2) receptors and in situ hybridisation histochemistry of D(1) and D(2) mRNA were performed. Using [3H]raclopride as the ligand, sub-chronic haloperidol administration produced a robust upregulation in D(2) binding in the striatum of rats which correlated with parallel increases in spontaneous locomotor activity from 24 h to 4 weeks. Using, [3H]SCH23390 as the ligand, D(1) binding was largely unaffected by the drug treatment. Non-significant changes were measured in the striatal expression of D(1) receptor mRNA or the nigral or striatal expression of D(2) receptor mRNA. Our findings have implications for the use of dopaminergic ligands in positron emission tomography (PET) imaging of patients under regimens of chronic neuroleptics in particular in the context of forthcoming trials of neural grafts in Huntington's disease (HD) striatum.

Systemic administration of 3-nitropropionic acid (3NPA) in experimental animals produces bilateral striatal lesions similar to those seen in Huntington's disease (HD) caudate and putamen. 3H[-CP55,940 binding to cannabinoid receptors in human basal ganglia nuclei has been shown to be highly susceptible to the earliest pathological changes in the HD brain. In this study, to assess further the suitability of 3NPA-induced striatal lesions as a model for HD neuropathology, we examined the effects of striatal lesions induced by the systemic administration of 3NPA on the binding of 3H[-CP55,940 to pre- and postsynaptic cannabinoid receptors in striatum, globus pallidus, entopeduncular nucleus and substantia nigra pars reticulata and also the effect of 3NPA-induced striatal lesions on the binding of 3H[-DAMGO to mu-opioid receptors in striatal striosomes. Systemic administration of 3NPA induced bilateral and symmetrical lesions in dorsolateral striatum. Within the lesion core, 3H[-CP55,940 and 3H[-DAMGO binding density was reduced to background levels. Beyond the immediate borders of the central core of the 3NPA-induced lesion, striatal binding density was not significantly different from that measured in unlesioned rats. 3H[-CP55,940 binding in globus pallidus, entopeduncular nucleus and substantia nigra in 3NPA-lesioned rats was significantly reduced compared to controls, and the individual decreases were similar for each site. However, these reductions were statistically marginal. These data suggest that, while producing striatal lesions which bear some similarity to those seen in HD, the consequences of 3NPA for striatopallidal and striatonigral efferent projections do not reflect the reported neurodegenerative changes seen in the HD brain.

Systemic administration of 3-nitropropionic acid (3NPA) in rats produces bilateral striatal lesions which are similar to those seen in Huntington's disease (HD). We examined the effects of systemic 3NPA on the expression of cytochrome oxidase (COX-II and COX-IV), succinate dehydrogenase (SDH) and astrocytic glial fibrillary acidic protein (GFAP) mRNAs and on the activity of COX and SDH as assessed by the density of histochemical staining. COX-II and COX-IV mRNA was reduced in rats with 3NPA-induced lesions, but not in those without, whereas SDH, but not COX, staining was significantly and dose-dependently reduced in both 3NPA treated groups. GFAP mRNA expression was increased in both intact striatum and cortex but was absent from the lesion core.

The epsilon4 allele of apolipoprotein E is associated with increased risk for developing Alzheimer's disease. To further understand the anatomical distribution of apolipoprotein E and its native receptors in the brain, we studied their messenger RNA expression in the adult rat brain under normal conditions and in response to an excitotoxic lesion to the hippocampus. In situ hybridization using oligonucleotide probes for apolipoprotein E, apolipoprotein J, the low density lipoprotein receptor, very low density lipoprotein receptor, low density lipoprotein receptor related protein, 39,000 mol. wt receptor-associated protein and glycoprotein 330/Megalin messenger RNA were performed on adjacent sections throughout the rat forebrain. Apolipoprotein E messenger RNA was abundantly expressed in the rat brain in both white and gray matter localizing to astrocytes but not neurons. Low density lipoprotein receptor-related protein and receptor-associated protein messenger RNA had a similar regional distribution but low density lipoprotein receptor-related protein messenger RNA was expressed by both neurons and glia, while the expression of receptor-associated protein messenger RNA was more highly expressed in neurons. Apolipoprotein J messenger RNA was expressed by neurons, glia and choroid plexus. The low density lipoprotein receptor and very low density lipoprotein receptor messenger RNA were found in both neurons and glia. Glycoprotein 330/Megalin messenger RNA was not detectable in the adult rat brain. In response to hippocampal lesions, apolipoprotein E and apolipoprotein J messenger RNAs were significantly up-regulated seven and 11 days post-lesion but the expression of low density lipoprotein receptor, low density lipoprotein receptor-related protein, receptor-associated protein, glycoprotein 330/Megalin, and very low density lipoprotein receptor messenger RNAs were unchanged. The expression of apolipoprotein E messenger RNA increased gradually beginning at three days while the expression of apolipoprotein J messenger RNA began to increase at seven days post-lesion. These findings further implicate apolipoproteins in the response of the brain to injury in vivo and suggest that transcriptional up-regulation of the apolipoprotein receptors studied is not a prominent feature in the response.

Using radioactive in situ hybridization, we have mapped the expression of Huntingtin-associated protein (HAP1) mRNA in rat brain at developmental stages (E12-E19, PO-P21), in adult rats (3 months) and in 'aged' (19-21 months) rats. Using two pairs of 45mer oligonucleotide probes specific for HAP1A and a probe which recognizes regions of both the HAP1A and HAP1B mRNA sequences (panHAP1), we find that the expression of HAP1 mRNA is specific to the CNS and restricted predominantly to anatomically connected limbic structures, particularly the amygdala (medial and corticomedial nuclei), the hypothalamus (arcuate, preoptic, paraventricular and lateral hypothalamic area), bed nucleus of the stria terminalis (BNST) and the lateral septal nuclei. HAP1 mRNA was detected in embryos at E12 and displayed a prevalent distribution in the developing limbic structures by E15. In aged, 19-21-months-old, rats there is a downregulation of HAP1 mRNA expression across all CNS loci where HAP1 was previously abundant. The lowest levels of HAP1 mRNA expression corresponded with the areas of greatest pathological cell loss in Huntington's disease (HD); the caudate putamen, globus pallidus and neocortex. These observations support the suggestion that HAP1 plays an important role in the neuropathology of HD.

N-methyl-D-aspartate (NMDA) and non-NMDA receptor-mediated manipulations of the cortical cholinergic input arising from the basal forebrain differentially affect cognitive function. We used [14C]-2-deoxyglucose autoradiography in conscious rats to map the effects of excitatory amino acid agonist infusions into the nucleus basalis magnocellularis (NBM) on cerebral functional activity, as reflected by local rates of glucose utilization. Acute stimulation of NBM neurones by local infusion of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), 15 min before glucose use measurement, resulted in glucose use reductions in nine cortical regions innervated by NBM efferents including prefrontal, frontal, sensorimotor and cingulate cortices. NMDA infusions altered glucose use in two cortical areas. Both AMPA and NMDA markedly increased glucose use in the striatum and globus pallidus, with concomitant perturbations in striato-pallidal projection targets including the substantia nigra, entopeduncular nucleus, subthalamic nucleus and lateral habenular nucleus. In contrast, the GABAA agonist muscimol did not affect glucose use in the NBM or neocortical regions, but induced glucose use increases in several subcortical nuclei including the substantia nigra and entopeduncular nucleus. The delayed effects of excitotoxic lesions were assessed 3 weeks after basal forebrain infusions of AMPA, NMDA, ibotenate or quisqualate. Statistically significant glucose use changes only occurred in the hypothalamus after NMDA, and the NBM after ibotenate infusions, although reduced cortical metabolism was apparent following AMPA-induced lesions of the NBM. Results support a dissociation between the functional sequelae of NMDA and non-NMDA receptor-mediated events in the basal forebrain, and long-term compensatory functional adaptation following cortical denervation.

The PDAPP transgenic mouse overexpresses human amyloid precursor protein V717F (PDAPP minigene) and develops age-related cerebral amyloid-beta protein (Abeta) deposits similar to senile plaques in Alzheimer's disease. We find age-related cortical and limbic Abeta deposition that begins at 8 months and progresses to cover 20-50% of the neuropil in cingulate cortex, entorhinal cortex, and hippocampus of 18-month-old heterozygotic animals. The regional patterns of transgene expression and amyloid deposition suggest that Abeta deposits occur at the terminals of overexpressing neurons. Amyloid deposition is associated with dystrophic neurites and extensive gliosis. However, stereological analysis shows that there is no overt neuronal loss in entorhinal cortex, CA1 hippocampal subfield, or cingulate cortex through 18 months of age. In addition, there is no apparent loss of mRNA encoding neuronal synaptic, cytoskeletal, or metabolic proteins. Thus, widespread Abeta deposition in 18-month-old heterozygotic mice produces neuritic alterations and gliosis without widespread neuronal death.

Neurofibrillary tangles in Alzheimer's disease are composed of hyperphosphorylated forms of the microtubule-associated protein tau. Based on biochemical criteria, several enzymes have emerged as potential tau protein kinases, including the extracellularly regulated kinases 1, 2 and 3. In situ hybridization was used to map the messenger RNA distribution of extracellularly regulated kinase 1, 2 and 3 in the adult rat brain and their response to excitotoxic hippocampal lesions was examined. Extracellularly regulated kinase 1 messenger RNA was uniformly expressed by glia, but was also present in the dentate gyrus and some other neuronal populations. Extracellularly regulated kinase 2 was exclusively neuronal and concentrated within the cortical laminae and the CA subfields of the hippocampal formation. Extracellularly regulated kinase 3 messenger RNA expression was similar to extracellularly regulated kinase 2 and was also present in neurons but the level of expression was lower. Extracellularly regulated kinases 2 and 3 messenger RNA expression was lost following excitotoxic injury, further supporting a neuronal localization. Extracellularly regulated kinase 1 messenger RNA expression appeared unaltered, suggesting a non-neuronal localization and lack of responsiveness to lesion at the level of transcription. By contrast, messenger RNA of sgk, a recently described serine/threonine kinase, was up-regulated by glial cells following excitotoxic injury. Based on their messenger RNA distribution, cellular localization and response to lesion, it is clear that each kinase may function differently in various signaling pathways. Extracellularly regulated kinase 2, however, is the only kinase with the proper messenger RNA distribution to contribute to neurofibrillary tangle formation in Alzheimer's disease.

Mutations in two recently identified genes appear to cause the majority of early-onset familial Alzheimer's disease (FAD). These two novel genes, presenilin 1 (PS1) and presenilin 2 (PS2) are members of an evolutionarily conserved gene family. The normal biological role(s) of the presenilins and the mechanism(s) by which the FAD-associated mutations exert their effect remain unknown. Employing in situ hybridization, we demonstrate that the expression patterns of PS1 and PS2 in the brain are extremely similar to each other and that messages for both are primarily detectable in neuronal populations. Immunochemical analyses indicate that PS1 and PS2 are similar in size and localized to similar intracellular compartments (endoplasmic reticulum and Golgi complex). FAD-associated mutations in PS1 and PS2 do not significantly modify either their migration patterns on SDS-polyacrylamide gel electrophoresis or their overall subcellular localization, although subtle differences in perinuclear staining were noted for mutant PS1.

The regional distribution of neurons containing alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor (GluR1-4) subunit immunoreactivity, relative to the distribution of cholinergic neurons within the basal forebrain of rats, was assessed using single- and dual-antigen immunocytochemistry. Analysis of serial sections stained with antibodies to nerve growth factor receptor (NGFr) and antibodies against each of the AMPA receptor subunits, GluR1-4, revealed a regional codistribution between NGFr- and GluR1- and GluR4-immunoreactive neurons in the medial septum, diagonal band nuclei and nucleus basalis magnocellularis. Quantitative dual-labelling immunocytochemistry using NGFr in combination with each of the GluR antibodies revealed > 65% colocalization between NGFr and GluR4 in each of the major cholinergic nuclei in the basal forebrain and 10-15% colocalization between NGFr, GluR1 and GluR2-3. The reticular nucleus of the thalamus, a structure known to be highly susceptible to AMPA-induced neurotoxicity, expressed GluR4 immunoreactivity exclusively. The observation that cholinergic neurons of the basal forebrain are also highly sensitive to AMPA and express the GluR4 subunit suggests that GluR4 may be important in AMPA receptor-mediated excitotoxicity.

The direct and transynaptic effects of lesions of the basal forebrain induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and ibotenic acid were investigated using quantitative in situ hybridization histochemistry. Probes complementary to the sequences of choline acetyltransferase mRNA, glutamate decarboxylase mRNA and preproenkephalin mRNA were used to assess direct lesion effects within the basal forebrain and probes for postsynaptic M-1 and M-3 muscarinic receptors were used to assess long-term changes in neocortical muscarinic receptor mRNA expression following cholinergic deafferentation. AMPA-induced basal forebrain lesions destroyed significantly more neurons that expressed choline acetyltransferase mRNA than ibotenic acid-induced lesions (90 versus 60%), but significantly fewer neurons which expressed either glutamate decarboxylase or preproenkephalin mRNA (61 versus 83% reduction in glutamate decarboxylase mRNA and 56 versus 79% reduction in preproenkephalin mRNA). AMPA-induced lesions did, however, destroy a significant proportion of the neurons which expressed glutamate decarboxylase and preproenkephalin mRNA (approximately 60%). The neurons spared following AMPA-induced lesions were typically situated dorsolaterally within the dorsal pallidum, although neurons expressing glutamate decarboxylase or preproenkephalin mRNA were frequently observed within the areas of greatest cholinergic neuronal loss, i.e. the region of the nucleus basalis magnocellularis. These findings suggest that there is a population of non-cholinergic pallidal neurons which are insensitive to AMPA but not to ibotenic acid, reflecting a possibly heterogeneous distribution of NMDA and non-NMDA subtypes of glutamate receptors within the rat basal forebrain. AMPA-induced lesions of the basal forebrain were, however, without significant effect on the levels of expression of M-1 and M-3 muscarinic receptor mRNAs in the cerebral neocortex.

A substantial body of literature has suggested that the memory and learning deficits associated with Alzheimer's disease are attributable to degeneration of the cholinergic magnocellular neurons of the nucleus basalis of Meynert (nbM). Subsequently, lesion-induced damage to the cholinergic projections from the nbM to the neocortex has been utilized extensively as an animal model of dementia. Ibotenic acid lesions of the basal forebrain have been found, for example, to produce deficits in a wide variety of tasks involving learning and memory. However, recently, with the availability of more potent cholinergic excitotoxins such as AMPA, it has become apparent that nbM lesions do not provide a simple animal model of the cognitive deficits in ageing and Alzheimer's disease. Further analysis suggests that many of the learning and memory impairments traditionally attributed to the cholinergic corticopetal system are due not to destruction of cholinergic neurons in the nbM, but instead result from the disruption of cortico-striatal outputs passing through the dorsal and ventral globus pallidus. Furthermore, experiments utilizing quisqualic acid and AMPA have revealed that the most convincing deficit observed as a result of such lesions is in visual attention. This role for the basal forebrain-cortical cholinergic system in attentional function is further supported by results obtained from complementary pharmacological studies. This does not exclude a role for acetylcholine in learning and memory processes. Rather, such cognitive processes appear to depend not upon the integrity of the nbM itself, but upon more rostral elements of the cholinergic basal forebrain system.

In these experiments, induction of the immediate early gene c-fos following excitation of striatal neurons has been used to investigate the organization of the ventral and dorsal striatopallidal systems and the relationship between striatal neurons and cholinergic neurons of the nucleus basalis magnocellularis (of Meynert, nbM). The results demonstrate that FOS immunoreactivity (ir) can be detected in ventral and dorsal striatal neurons following infusions of the non-N-methyl-D-aspartic acid (NMDA) glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA). This activation and increased expression of FOS in striatal neurons was itself associated with the sustained appearance of FOS-ir in neurons of the ipsilateral ventral and dorsal pallidum, subthalamic nucleus and some thalamic nuclei. Infusions of AMPA into the ventral striatum (VS), but not the dorsal striatum (DS), also resulted in the appearance of FOS-ir in a proportion (17%) of the cholinergic neurons of the nbM. By combining the retrograde transport of Fluoro-Gold with FOS immunocytochemistry, it was also possible to demonstrate that approximately 46% and 58% of the pallidal neurons containing FOS-ir after infusions of AMPA into the VS or DS, respectively, directly project to the subthalamic nucleus. Taken together, these observations suggest that visualizing the protein product of transsynaptic c-fos induction provides an effective way to study the topographic and transsynaptic, within-system consequences of striatal activation.

These experiments investigated, by studying patterns of c-fos expression, the distribution of neurons activated or destroyed by the infusion into the basal forebrain of various excitatory amino acids at toxic and subtoxic doses. The results of experiment 1 showed that N-methyl-D-aspartic acid (NMDA), quisqualic acid and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) differentially increased the expression of c-fos in magnocellular cholinergic nucleus basalis, dorsal and ventral pallidal neurons. AMPA was the most, and NMDA the least, effective in inducing FOS in nucleus basalis magnocellularis (nbM) neurons, with quisqualic acid having an intermediate effect, whereas the reverse was true in terms of the induction of FOS in pallidal neurons. In experiment 2, it was demonstrated that, in animals with ibotenic acid-induced lesions of the basal forebrain that were targetted on the nbM, virtually no pallidal neurons could be visualized that expressed FOS following AMPA-induced excitation of the dorsal and ventral striatum. By contrast, in animals with AMPA-induced lesions of the nbM, excitation of the striatum was followed by the expression of FOS in many dorsal and ventral pallidal neurons. Thus, infusions of AMPA into the basal forebrain appears preferentially to activate or destroy, depending on the concentration infused, cholinergic nbM neurons, whereas ibotenic acid or NMDA preferentially destroys or activates neurons of the dorsal and ventral pallidum. These results provide novel and complementary information regarding the organization of the basal forebrain and allow a clearer understanding of the different behavioural consequences of NMDA agonist-induced and non-NMDA agonist-induced excito-toxic lesions of this area.

Excitotoxic lesions of the basal forebrain were made by infusing either alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) or ibotenic acid. Acquisition and performance of spatial learning in the Morris water maze, over a ten day, two trials per day, training regimen were unaffected by the AMPA-induced lesions which reduced cortical choline acetyltransferase activity by 70%. However, acquisition was significantly impaired in rats with ibotenic acid-induced lesions that reduced cortical choline acetyltransferase by 50%. Additionally, ibotenic acid-lesioned rats swam further than either sham or AMPA-lesioned rats, in the "training" quadrant during a probe trial, in which the escape platform was removed, suggesting a perseverative search strategy. Lesions induced with AMPA, but not ibotenate, significantly impaired the acquisition of "step-through" passive avoidance. Both AMPA- and ibotenate-induced lesions significantly impaired the 96 h retention of passive avoidance, but the effect of AMPA was greater on latency measures. Histological analysis revealed that AMPA infusions destroyed more choline acetyltransferase-immunoreactive neurons than did ibotenate infusions but, unlike ibotenate, spared the overlying dorsal pallidum and also parvocellular, non-choline acetyltransferase-immunoreactive neurons in the ventral pallidal/substantia innominata region of the basal forebrain. The impairment in acquisition of the water maze following ibotenate-induced basal forebrain lesions therefore appears unrelated to damage to cholinergic neurons of the nucleus basalis of Meynert and to depend instead on damage to pallidal and other neurons in this area. The AMPA- and perhaps also the ibotenate-induced impairment in the retention of passive avoidance appears to be more directly related to destruction of cholinergic neurons of the nucleus basalis. These data are discussed in the context of cortical cholinergic involvement in mnemonic processes.

Two experiments tested the hypothesis that the deficits in conditional discrimination learning produced by ibotenic acid-induced lesions of the ventral pallidum and substantia innominata are produced by loss of the magnocellular cholinergic cells in the nucleus basalis and adjacent regions. Experiment 1 replicated the previously reported deficit in conditional learning produced by ibotenate-induced lesions of the ventral pallidum/substantia innominata, but failed to demonstrate any restoration of learning by a subchronic regimen of the acetylcholinesterase inhibitor physostigmine sufficient to produce significant (30%), but equivalent, degrees of inhibition in the frontal cortex of ventral pallidum/substantia innominata-lesioned or sham-operated rats. Experiment 2 examined the effects of quisqualic acid-induced lesions of the ventral pallidum/substantia innominata. According to most of the measures of learning employed, the quisqualic acid-induced lesion of the ventral pallidum/substantia innominata failed to impair conditional learning, even though the quisqualate-induced lesion produced greater degrees of cholinergic neuron destruction than the ibotenate-induced lesion, as measured in terms of reductions in cortical choline acetyltransferase activity (44% vs 27%). Although consideration of individual data suggested that very high (60%) levels of choline acetyltransferase reduction in Experiment 2 might have detrimental effects of conditional learning, the overall failure of the quisqualate-induced lesions of the ventral pallidum/substantia innominata to impair learning is to be contrasted with the significant behavioural effects of ibotenate-induced lesions. Histological and immunocytochemical analysis showed that the quisqualate-induced lesion, unlike that produced by ibotenate, tended to produce less damage to the overlying dorsal globus pallidus and to parvocellular neurons of the ventral pallidum/substantia innominata, thus implicating these nonspecific effects of ibotenate-induced lesions in their behavioural effects. The present results question previous interpretations of the behavioural effects of ibotenate-induced lesions of the ventral pallidum/substantia innominata in terms of damage inflicted on the cortically-projecting cholinergic cells of the nucleus basalis, and suggest that quisqualic acid, although also nonspecific in its excitotoxic effects, is nevertheless more selective for producing damage to cholinergic neurons in the ventral pallidum/substantia innominata than ibotenic acid.

Two experiments examined the effects of excitotoxic lesions of the substantia innominata on cholinergic activity in the neocortex and on performance in a paradigm measuring selective attention in the rat. In Expt. 1, ibotenate-induced lesions produced approximately 30% reductions in cortical choline acetyltransferase (ChAT) activity, and damage to wide regions of the substantia innominata and ventral pallidum. The rats were impaired in their ability to localize brief visual targets in a serial reaction time task, as measured by reduced choice accuracy. This impairment was particularly evident at short stimulus durations, but the lesioned rats did not exhibit evidence of primary visual sensory dysfunction and exhibited only minor deficits when the stimuli were presented unpredictably. The deficit was exacerbated when distracting white noise was interpolated into the task. The rats with lesions were also slower to respond correctly, probably resulting partly from the adoption of a speed/error trade-off strategy, and were slower to collect earned food pellets, although they made no more errors of omission than controls. In Expt. 2, quisqualate-induced lesions produced fewer signs of non-specific damage and 50% reductions in cortical ChAT activity. This lesion produced generally qualitatively similar, but weaker effects to those of ibotenate-induced lesions. It was notable that many of the deficits following either ibotenate- or quisqualate-induced lesions lasted for several months after surgery. The results are discussed in terms of the cholinergic hypothesis of cognitive dysfunction. It is argued that lesions of the substantia innominata, including the magnocellular cholinergic neurons of the nucleus basalis of Meynert, produce deficits in attentional processing, which may not result from damage specifically to cholinergic cells. However, the longevity of the effects makes these preparations suitable for further exploration of the restorative effects of cholinergic treatments.