NPY-mRNA expressions in the nucleus accumbens, caudate putamen and cerebral cortex of apomorphine-susceptible and apomorphine-unsusceptible rats

Abstract

Using the apomorphine-induced stereotyped gnawing response as a selection criterion, two distinct groups of rats can be distinguished, apomorphine-susceptible (APO-SUS) and apomorphine-unsusceptible (APO-UNSUS) rats. These two lines differ in several components of both striatal and extrastriatal areas. This study deals with the expression of neuropeptide Y (NPY)mRNA-expressing neurons in the nucleus accumbens, caudate putamen and cerebral cortex of both rat lines, using non-radioactive in situ hybridisation. The morphology of the neurons in the three regions is similar, viz. oblong, rectangular or triangular, with two or three processes. The neurons are homogeneously distributed in all regions, and in the nucleus accumbens they are particularly numerous ventrally to the anterior commissure. Using automated image analysis, the mean numerical density of NPYmRNA-positive neurons per brain region and the mean NPYmRNA expression level per neuron per brain region were determined. No differences appear in the numerical densities of NPYmRNA-containing neurons in the nucleus accumbens, caudate putamen and cortex between APO-SUS and APO-UNSUS rats. However, distinct differences between the rat lines are present in the level of NPYmRNA expression per neuron in the nucleus accumbens and in the caudate putamen, showing that NPY contributes to the differential neurochemical make-up of these rat lines that is responsible for their obvious differences in behaviour, physiology and immune competence.

On the relevance of the NPY2-receptor variation for modes of action cascading processes

“…parallel) mode of action cascading (Stock et al, 2014a(Stock et al, , 2014b, we expect G allele carriers to show a more parallel (inefficient) mode of action cascading than homozygous A allele carriers. Due to the findings that NPY affects striatal functioning (Caberlotto et al, 2000;Roubos et al, 2003;Stanic et al, 2006;Tepper et al, 2010) and that alterations in fronto-striatal loops affect mechanisms mediating between stimulus evaluation and responding during action cascading (Beste and Saft, 2013), we expect especially these aspects to be affected. Neurophysiologically, these processes are reflected by the P3 event-related potential (ERP) (Mückschel et al, 2013;Polich, 2007;Verleger et al, 2005;Sigman and Dehaene, 2008).…”

“…One of these is neuropeptide Y (NPY). NPY is highly expressed in the striatum (Caberlotto et al, 2000;Roubos et al, 2003;Stanic et al, 2006;Tepper et al, 2010), and it is one of the most abundant peptides in the mammalian brain. NPY and dopamine neurons are in close juxtaposition in the striatum (Adewale et al, 2007;Aoki and Pickel, 1990) and may therefore mutually influence their respective neurotransmission.…”