Long-term effects of a single adult methamphetamine challenge: minor impact on dopamine fibre density in limbic brain areas of gerbils.
BACKGROUND
The aim of the study was to test long-term effects of (+)-methamphetamine (MA) on the dopamine (DA) innervation in limbo-cortical regions of adult gerbils, in order to understand better the repair and neuroplasticity in disturbed limbic networks.


METHODS
Male gerbils received a single high dose of either MA (25 mg/kg i.p.) or saline on postnatal day 180. On postnatal day 340 the density of immunoreactive DA fibres and calbindin and parvalbumin cells was quantified in the right hemisphere.


RESULTS
No effects were found in the prefrontal cortex, olfactory tubercle and amygdala, whereas the pharmacological impact induced a slight but significant DA hyperinnervation in the nucleus accumbens. The cell densities of calbindin (CB) and parvalbumin (PV) positive neurons were additionally tested in the nucleus accumbens, but no significant effects were found. The present results contrast with the previously published long-term effects of early postnatal MA treatment that lead to a restraint of the maturation of DA fibres in the nucleus accumbens and prefrontal cortex and a concomitant overshoot innervation in the amygdala.


CONCLUSIONS
We conclude that the morphogenetic properties of MA change during maturation and aging of gerbils, which may be due to physiological alterations of maturing vs. mature DA neurons innervating subcortical and cortical limbic areas. Our findings, together with results from other long-term studies, suggest that immature limbic structures are more vulnerable to persistent effects of a single MA intoxication; this might be relevant for the assessment of drug experience in adults vs. adolescents, and drug prevention programs.
Department of Neuroanatomy, Faculty of Biology, University of Bielefeld, Universitätsstr, 25, D-33615 Bielefeld, Germany. susanne.brummelte@uni-bielefeld.de
Susanne
S
Brummelte
Thorsten
T
Grund
Andrea
A
Czok
Gertraud
G
Teuchert-Noodt
Jörg
J
Neddens