Repeated amphetamine administration induces Fos in prefrontal cortical neurons that project to the lateral hypothalamus but not the nucleus accumbens or basolateral amygdala.
BACKGROUND
The development of sensitization to amphetamine (AMPH) is dependent on increases in excitatory outflow from the medial prefrontal cortex (mPFC) to subcortical centers. These projections are clearly important for the progressive enhancement of the behavioral response during drug administration that persists through withdrawal.


OBJECTIVE
The objective of this study was to identify the mPFC subcortical pathway(s) activated by a sensitizing regimen of AMPH.


METHODS
Using retrograde labeling techniques, Fos activation was evaluated in the predominant projection pathways of the mPFC of sensitized rats after a challenge injection of AMPH.


RESULTS
There was a significant increase in Fos-immunoreactive cells in the mPFC, nucleus accumbens (NAc), basolateral amygdala (BLA), and lateral hypothalamus (LH) of rats treated repeatedly with AMPH when compared to vehicle-treated controls. The mPFC pyramidal neurons that project to the LH but not the NAc or BLA show a significant induction of Fos after repeated AMPH treatment. In addition, we found a dramatic increase in Fos-activated orexin neurons.


CONCLUSIONS
The LH, a region implicated in natural and drug reward processes, may play a role in the development and persistence of sensitization to repeated AMPH through its connections with the mPFC and possibly through its orexin neurons.
Morshedi
Maud M
MM
Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA. maud.morshedi@students.rosalindfranklin.edu
Meredith
Gloria E
GE
D000661:Amphetamine / Q000494:pharmacology*; D000679:Amygdala / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D009714:Nucleus Accumbens / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000068797:Orexins; D010477:Perfusion; D017397:Prefrontal Cortex / Q000166:cytology / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000235:genetics; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013266:Stilbamidines
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D000697:Central Nervous System Stimulants; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos; D013266:Stilbamidines; D000661:Amphetamine