The hyperfunctioning @entity935 hypothesis in the mesocorticolimbic (MCL) system has been addressed by a neurogenetic approach in model systems. Thus, a morphometric analysis was carried out on neurons of origin of Substantia Nigra (SN) and Ventral Tegmental Area (VTA) @entity935 systems of the Naples High-Excitability (NHE), Low-Excitability (NLE) and control lines. Male adult @entity35 were tested in a spatial novelty for indices of activity and non-selective attention. Mesencephalic coronal sections were processed for @entity669 hydroxylase (TH) immunohistochemistry and cytochromoxidase (C.O.) histochemistry. Image analysis in the rostro-caudal plane showed (i) a higher neuron size of TH+ elements in the VTA of NHE and NLE, across the entire structure in the NHE, and only in the middle portion in the NLE; (ii) a higher expression of TH in the neuropil of the VTA in NHE; (iii) a lower C.O. activity in both NLE and NHE; (iv) no differences in the SN. The larger neuron size in both NHE and NLE @entity35 as compared with control @entity35 , along with higher TH expression mainly in the NHE, in absence of any relevant alteration in the SN, reveals an unbalance between the two @entity935 systems and a subsequent alteration in limbic (reward, motivation, sustained attention) functions. The decreased C.O. activity might be due to reduced feedback inhibition by striatal @entity1246 neurons and interneurons leading to increased DA neuron firing. In conclusion, the increased behavioral activity and impaired attention observed in the NHE @entity35 are associated to hyperfunctioning MCL system in this genetic model of @entity71 ( @entity71 ).

A morphometric evidence for a hyperfunctioning mesolimbic system in an animal model of XXXX .

@entity1246 :: ('MESH:D005680', 'Chemical') :: ['GABA'] @entity935 :: ('MESH:D004298', 'Chemical') :: ['dopamine'] @entity71 :: ('MESH:D001289', 'Disease') :: ['Attention-Deficit Hyperactivity Disorder', 'ADHD'] @entity35 :: ('10116', 'Species') :: ['rats'] @entity669 :: ('CHEBI:18186', 'Chemical') :: ['tyrosine']
@entity71 :: (MESH:D001289,Disease) :: ['ADHD']
