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Effects of BDNF and NT‐4/5 on Striatonigral Neuropeptides or Nigral GABA Neurons In Vivo
Author(s) -
Arenas Ernest,
Åkerud Peter,
Wong Vivien,
Boylan Carolyn,
Person Håkan,
Lindsay Ronald M.,
Altar C. Anthony
Publication year - 1996
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1996.tb01314.x
Subject(s) - neuroscience , neuropeptide , in vivo , psychology , biology , medicine , receptor , microbiology and biotechnology
Supranigral infusions of the TrkB‐receptor‐preferring neurotrophins BDNF or NT‐4/5 augment locomotor behaviours, pars compacta firing rates and striatal dopamine metabolism. However these actions of BDNF or NT‐4/5 may involve other neurotransmitter systems in addition to dopamine neurons in the substantia nigra. We thus investigated the effects of 2‐week supranigral infusions of BDNF or NT‐4/5 on rat peptidergic striatonigral neurons and nigral GABAergic neurons. Radioimmunoassay revealed that BDNF and NT‐4/5 elevated substantia nigra levels of substance P (by 46 and 57% respectively) and substance K (by 64 and 81%). In addition, BDNF elevated substance K by 59% in a nigral projection area, the superior colliculus. NT‐4/5 elevated dynorphin A in the substantia nigra (by 52%) and met ‐enkephalin in substantia nigra and globus pallidus (by 89%). None of these neuropeptides were altered in the striatum. Consistent with these findings, supranigral infusions of BDNF elevated the mRNA for preprotachykinin A in striatal neurons. In the same animals, glutamic acid decarboxylase (GAD) 67 mRNA was increased by 48% in the substantia nigra. The cross‐sectional area of GAD 67 ‐positive neuronal somata in the BDNF‐infused nigra was increased by 59%, and 70% of nigral GABAergic neurons had a cross‐sectional area >550 μm 2 , whereas 95% of the neurons in vehicle‐infused animals had cross‐sectional areas <550 μm 2. Thus, supranigral infusions of BDNF or NT‐4/5 increase tachykinin mRNA and protein levels within striatonigral neurons and increase the size and GAD 67 mRNA expression levels of nigral GABAergic neurons. These results suggest that BDNF or NT‐4/5 may modify the output of the basal ganglia not only through effects on dopamine neurons but also by increasing neurotransmission in striatonigral peptidergic and nigral GABAergic pathways.