deficit in hippocampal PV (Zhang and Reynolds 2002) is
one of the most robust neurochemical findings in the disease,
which also demonstrates a substantial, if less severe,
decrement in frontal cortical PV–IR neurons (Beasley and
Reynolds 1997; Beasley et al. 2002), with additional defi-
cits in CB- but not CR–IR cells (Beasley et al. 2002).
Consistent with these findings, a previous report of a nonpharmacological
developmental intervention, isolation
rearing, resulting in enduring behavioural deficits considered
to model aspects of schizophrenia, has also found
significant depletions in PV- and CB- but not CR–IR
neurons in the hippocampus (Harte et al. 2007).
This study showed a reduction of CR–IR neurons in the
frontal cortex in ED and ED-Binge groups. Such areduction is not usually observed in schizophrenia or its
NMDA antagonist rodent models, suggesting that the
chronic METH regime may induce a more generalized
GABAergic pathology in the frontal cortex, although the
pattern of hippocampal CBP loss remains selective. There
are limitations to the current study; ethical and pragmatic
reasons limited the numbers of animals studied, and
resources restricted the number of sections stained to two
or three for each CBP in each animal; although cell density
in both hemispheres in each section was determined.
Nevertheless, the findings appear robust with generally
high levels of statistical significance
neurotoxic mechanism remains unclear. These results add
to other evidence indicating deficits in cortical GABA after
METH administration, reviewed by Hsieh et al. (2014).
There is also evidence of losses in glutamatergic neurons,
which may be a consequence of deficits of inhibitory
GABAergic interneurons (Jiao et al. 2015). Consistent with
this is the observation that CB–IR neuronal deficits are
found to precede the loss of pyramidal cells (Kuczenski
et al. 2007). It may be that METH exerts these effects via
excessive dopamine-mediated activation of glutamate
release leading to excitotoxic GABAergic neuronal damage
(Hsieh et al. 2014). An alternative neurotoxic mechanism,
not necessarily inconsistent with an excitotoxic
process, is one of the METH-induced oxidative damages,