The substantia nigra in the pathology of schizophrenia: A review on post-mortem and molecular imaging findings

Dysregulation of striatal dopamine is considered to be an important driver of pathophysiological processes in schizophrenia. Despite being one of the main origins of dopaminergic input to the striatum, the (dys)functioning of the substantia nigra (SN) has been relatively understudied in schizophrenia. Hence, this paper aims to review different molecular aspects of nigral functioning in patients with schizophrenia compared to healthy controls by integrating post-mortem and molecular imaging studies. We found evidence for hyperdopaminergic functioning in the SN of patients with schizophrenia (i.e. increased AADC activity in antipsychotic-free/-naïve patients and elevated neuromelanin accumulation). Reduced GABAergic inhibition (i.e. decreased density of GABAergic synapses, lower VGAT mRNA levels and lower mRNA levels for GABA_A receptor subunits), excessive glutamatergic excitation (i.e. increased NR1 and Glur5 mRNA levels and a reduced number of astrocytes), and several other disturbances implicating the SN (i.e. immune functioning and copper concentrations) could potentially underlie this nigral hyperactivity and associated striatal hyperdopaminergic functioning in schizophrenia. These results highlight the importance of the SN in schizophrenia pathology and suggest that some aspects of molecular functioning in the SN could potentially be used as treatment targets or biomarkers.

The neuropathology of autism: A systematic review of post-mortem studies of autism and related disorders

Post-mortem studies allow for the direct investigation of brain tissue in those with autism and related disorders. Several review articles have focused on aspects of post-mortem abnormalities but none has brought together the entire post-mortem literature. Here, we systematically review the evidence from post-mortem studies of autism, and of related disorders that present with autistic features. The literature consists of a small body of studies with small sample sizes, but several remarkably consistent findings are evident. Cortical layering is largely undisturbed, but there are consistent reductions in minicolumn numbers and aberrant myelination. Transcriptomics repeatedly implicate abberant synaptic, metabolic, proliferation, apoptosis and immune pathways. Sufficient replicated evidence is available to implicate non-coding RNA, aberrant epigenetic profiles, GABAergic, glutamatergic and glial dysfunction in autism pathogenesis. Overall, the cerebellum and frontal cortex are most consistently implicated, sometimes revealing distinct region-specific alterations. The literature on related disorders such as Rett syndrome, Fragile X and copy number variations (CNVs) predisposing to autism is particularly small and inconclusive. Larger studies, matched for gender, developmental stage, co-morbidities and drug treatment are required.

Animal Models in Forensic Science Research: Justified Use or Ethical Exploitation?

A moral dilemma exists in biomedical research relating to the use of animal or human tissue when conducting scientific research. In human ethics, researchers need to justify why the use of humans is necessary should suitable models exist. Conversely, in animal ethics, a researcher must justify why research cannot be carried out on suitable alternatives. In the case of medical procedures or therapeutics testing, the use of animal models is often justified. However, in forensic research, the justification may be less evident, particularly when research involves the infliction of trauma on living animals. To determine how the forensic science community is dealing with this dilemma, a review of literature within major forensic science journals was conducted. The frequency and trends of the use of animals in forensic science research was investigated for the period 1 January 2012-31 December 2016. The review revealed 204 original articles utilizing 5050 animals in various forms as analogues for human tissue. The most common specimens utilized were various species of rats (35.3%), pigs (29.3%), mice (17.7%), and rabbits (8.2%) although different specimens were favored in different study themes. The majority of studies (58%) were conducted on post-mortem specimens. It is, however, evident that more needs to be done to uphold the basic ethical principles of reduction, refinement and replacement in the use of animals for research purposes.