Age-Dependent Changes in Calretinin Immunoreactivity and its Protein Level in the Gerbil Hippocampus

Abstract

Calretinin (CR)-immunoreactive interneurons are well known as the interneuron specific interneurons in the hippocampus. CR-immunoreactive neurons form cellular network and regulate the activity of other GABAergic inhibitory interneurons in the hippocampus. In the present study, we investigated age-related changes in CR-immunoreactive neurons and protein levels in the gerbil hippocampus during normal aging. In all subregions of the gerbil hippocampus, the number of CR-immunoreactive neurons was significantly decreased in the postnatal month 6 (PM 6) group compared to that in the PM 1 group. Thereafter, CR-immunoreactive neurons were decreased with age. In addition, the number of CR-immunoreactive cells in the subgranular zone were significantly decreased in the PM 6 group. We also observed that CR protein levels were decreased gradually with age. These results indicate that both CR immunoreactivity and its protein level were decreased with age in the gerbil hippocampus during normal aging.

Melatonin maintains calcium-binding calretinin-positive neurons in the dentate gyrus during aging of Balb/C mice

“…1A). In accordance with the images, we confirmed that CR-distribution was not limited to the nucleus of immunoreactive cells located at the GCL of the DG (Lee et al, 2010;Toth et al, 2010). Besides, the antibody used for immunohistochemistry but tested in whole protein extracts of hippocampus by immunoblotting showed a protein band of~29 kDa, which corresponded to the expected molecular weight of CR (Fig.…”

“…Thus, CR is present during immature stages of hippocampal neuronal development, but its expression stops when newborn cells are functionally integrated in the DG (Brandt et al, 2003;Ge et al, 2006). Here, we confirmed that CR-cells showed a well-stained nucleus within oval and round somas, but also the protein is located at the dendrites of newborn granular cells in the DG, expression that is associated with the more mature dendrite morphology identified by the coexpression of CR with doublecortin (Brandt et al, 2003;Lee et al, 2010;Plumpe et al, 2006).…”

“…Similarly, a decline in CR-positive cells was reported in C57Bl6 mice (Mirochnic et al, 2009). In this regard, the density of CR-neurons in the hippocampus decreases in old humans (Bu et al, 2003) and during aging of gerbils (Lee et al, 2010). In the same sense, adult hippocampal neurogenesis (Couillard-Despres et al, 2009;Jinno, 2011;Kuhn et al, 1996) and plasma melatonin levels are reduced during aging (Brusco et al, 2000;Liu et al, 1999;Waldhauser et al, 1993).…”

“…This protein acts as a calcium-buffer/binding (Schwaller, 2014) and is essential for murine hippocampal neurogenesis (Brandt et al, 2003;Todkar et al, 2012). During aging CR-protein expression and the number of CR-neurons decrease in the whole hippocampus (Bu et al, 2003;Lee et al, 2010;Mirochnic et al, 2009). This evidence is in line of both the decline in adult hippocampal neurogenesis (Couillard-Despres et al, 2009;Jinno, 2011) and reduced plasma levels of melatonin in some neuropsychiatric disorders including neurodegenerative diseases (i.e.…”

Differential Effects of Treadmill Exercise on Calretinin Immunoreactivity in Type 2 Diabetic Rats in Early and Chronic Diabetic Stages

“…As a result of the comparison between the Co12-ZDF and Co30-ZDF groups, we can conclude that, as diabetes progressed, the number of CR-immunopositive neurons and the intensity of the immunoreactivity in the DG were reduced. An agedependent decrease in the number of CR-immunoreactive neurons was also reported previously [23,45], and we observed a decrease in the Co30-ZLC group compared to the Co12-ZLC group. This suggests that both diabetes progression and aging can affect the level of CR expression in the DG.…”