Iron and n-3 fatty acid depletion, alone and in combination, during early development provoke neurochemical changes, anhedonia, anxiety and social dysfunction in rats

Objectives: Both iron and omega-3 (n-3) fatty acids (FA) play important roles in the development and functioning of the brain. We investigated the effects of n-3 FA and iron deficiencies, alone and in combination, during early development on behaviour and brain monoamines in rats. Methods: Using a 2-factorial design, female Wistar rats were randomly allocated to one of four diet groups: Control, n-3 FA deficient (n-3 FAD), iron deficient (ID), or n-3 FAD + ID. Females received these diets throughout mating, pregnancy and lactation. Offspring (n = 24/group; male:female = 1:1) continued on the same diet until post-natal day 42-45, and underwent a sucrose preference test (SPT), novel object recognition test, elevated plus maze (EPM) and social interaction test (SIT). Results: ID offspring consumed less sucrose in the SPT and spent more time in closed arms and less time in open arms of the EPM than non-ID offspring. In female offspring only, ID and n-3 FAD reduced time approaching and together in the SIT, with an additive effect of ID and n-3 FAD for even less time approaching and spent together in the n-3 FAD + ID group compared to controls. ID offspring had higher striatal dopamine and norepinephrine and lower frontal cortex dopamine concentrations. N-3 FAD and ID affected frontal cortex serotonin concentrations in a sex-specific manner. Conclusions: Our results suggest that ID and n-3 FAD during early development provoke anhedonia, anxiety and social dysfunction in rats, with potential additive and attenuating effects when combined. These effects may in part be attributed to disturbances in brain neurochemistry and may be sex-specific.

Accelerated aging in people living with HIV: The neuroimmune feedback model

People living with HIV (PLWH) experience earlier onset of aging-related comorbidities compared to their counterparts without HIV. This paper lays out a theoretical model to explain why PLWH experience accelerated aging. Briefly, the model is structured as follows. PLWH experience disproportionately heavy burdens of psychosocial stress across the life course. This psychosocial stress increases risks for depressive symptoms and problematic substance use. Depressive symptoms and problematic substance use interfere with long-term adherence to antiretroviral therapy (ART). Lower ART adherence, in turn, exacerbates the elevated systemic inflammation stemming from HIV infection. This inflammation increases risks for aging-related comorbidities. Systemic inflammation also reduces connectivity in the brain's central executive network (CEN), a large-scale brain network that is critical for coping with stressful circumstances. This reduced capacity for coping with stress leads to further increases in depressive symptoms and problematic substance use. Together, these changes form a neuroimmune feedback loop that amplifies the impact of psychosocial stress on aging-related comorbidities. In this paper, I review the existing evidence relevant to this model and highlight directions for future research.

Putative neural mechanisms underlying release-mode-specific abnormalities in dopamine neural activity in a schizophrenia-like model: The distinct roles of glutamate and serotonin in the impaired regulation of dopamine neurons

Abnormalities in dopamine function might be related to psychiatric disorders such as schizophrenia. Even at the same concentration, dopamine exerts opposite effects on information processing in the prefrontal cortex depending on independent dopamine release modes known as tonic and phasic releases. This duality of dopamine prevents a blanket interpretation of the implications of dopamine abnormalities for diseases on the basis of absolute dopamine levels. Moreover, the mechanisms underlying the mode-specific dopamine abnormalities are not clearly understood. Here, I show that the two modes of dopamine release in the prefrontal cortex of a schizophrenia-like model are disrupted by different mechanisms. In the schizophrenia-like model established by perinatal exposure to inflammatory cytokine, epidermal growth factor, tonic release was enhanced and phasic release was decreased in the prefrontal cortex. I examined the activity of dopamine neurons in the ventral tegmental area (VTA), which sends dopamine projections to the prefrontal cortex, under anaesthesia. The activation of VTA dopamine neurons during excitatory stimulation (local application of glutamate or N-methyl-d-aspartic acid [NMDA]), which is associated with phasic activity, was blunt in this model. Dopaminergic neuronal activity in the resting state related to tonic release was increased by disinhibition of the dopamine neurons due to the impairment of 5HT2 (5HT2A) receptor-regulated GABAergic inputs. Moreover, chronic administration of risperidone ameliorated this disinhibition of dopaminergic neurons. These results provide an idea about the mechanism of dopamine disturbance in schizophrenia and may be informative in explaining the effects of atypical antipsychotics as distinct from those of typical drugs.

[Touch, a crucial sense in social interactions to improve homeostasis in aging and promote healthy longevity]

Aging is associated with the generalized deterioration of the organism, being of great relevance experienced by homeostatic systems such as the nervous, immune, and endocrine systems, which increases the risk of morbidity and mortality. Among the lifestyle strategies that have been researched to improve these systems and achieve greater healthy longevity, this review will focus on the social environment. In order to verify the effectiveness of these both in the improvement of homeostasis and in life expectancy, the research carried out with experimental animals that have allowed this to be done will be discussed. In addition, as it has been observed that physical contact is crucial for the positive outcomes of social interaction on homeostatic systems and longevity to occur, we will focus on that mechanism, as well as some of the possible molecular pathways underlying the effects found.

Schizophrenia Animal Modeling with Epidermal Growth Factor and Its Homologs: Their Connections to the Inflammatory Pathway and the Dopamine System

Epidermal growth factor (EGF) and its homologs, such as neuregulins, bind to ErbB (Her) receptor kinases and regulate glial differentiation and dopaminergic/GABAergic maturation in the brain and are therefore implicated in schizophrenia neuropathology involving these cell abnormalities. In this review, we summarize the biological activities of the EGF family and its neuropathologic association with schizophrenia, mainly overviewing our previous model studies and the related articles. Transgenic mice as well as the rat/monkey models established by perinatal challenges of EGF or its homologs consistently exhibit various behavioral endophenotypes relevant to schizophrenia. In particular, post-pubertal elevation in baseline dopaminergic activity may illustrate the abnormal behaviors relevant to positive and negative symptoms as well as to the timing of this behavioral onset. With the given molecular interaction and transactivation of ErbB receptor kinases with Toll-like receptors (TLRs), EGF/ErbB signals are recruited by viral infection and inflammatory diseases such as COVID-19-mediated pneumonia and poxvirus-mediated fibroma and implicated in the immune-inflammatory hypothesis of schizophrenia. Finally, we also discuss the interaction of clozapine with ErbB receptor kinases as well as new antipsychotic development targeting these receptors.