Odor discrimination learning in the Indian greater short-nosed fruit bat (Cynopterus sphinx): differential expression of Egr-1, C-fos and PP-1 in the olfactory bulb, amygdala and hippocampus

Abstract

Activity-dependent expression of immediate-early genes (IEGs) is induced by exposure to odour. The present study was designed to investigate whether there is differential expression of IEGs (, ) in the brain region mediating olfactory memory in the Indian greater short-nosed fruit bat, We assumed that differential expression of IEGs in different brain regions may orchestrate a preference odour (PO) and aversive odour (AO) memory in We used preferred (0.8% w/w cinnamon powder) and aversive (0.4% w/v citral) odour substances, with freshly prepared chopped apple, to assess the behavioural response and induction of IEGs in the olfactory bulb, hippocampus and amygdala. After experiencing PO and AO, the bats initially responded to both, later only engaging in feeding bouts in response to the PO food. The expression pattern of EGR-1 and c-Fos in the olfactory bulb, hippocampus and amygdala was similar at different time points (15, 30 and 60 min) following the response to PO, but was different for AO. The response to AO elevated the level of c-Fos expression within 30 min and reduced it at 60 min in both the olfactory bulb and the hippocampus, as opposed to the continuous increase noted in the amygdala. In addition, we tested whether an epigenetic mechanism involving protein phosphatase-1 (PP-1) acts on IEG expression. The observed PP-1 expression and the level of unmethylated/methylated promoter revealed that expression is possibly controlled by odour-mediated regulation of PP-1. These results in turn imply that the differential expression of in the hippocampus and amygdala may contribute to olfactory learning and memory in.

Role of Probiotic Strain Lactobacillus acidophilus in the Reversal of Gut Dysbiosis Induced Brain Cognitive Decline

“…These synthesized neurotransmitters may positively regulate the calcium influx (CI), adenyl cyclase (AC), PKA, and cAMP levels in a stress-free environment. Regulation of these abovementioned molecules results in the phosphorylation of CREB followed by the activation of IEGs and PSD proteins (Mukilan et al 2015;Mukilan et al 2018a;Thangaleela et al 2018;Mukilan 2023). However, an imbalance in the regulation and phosphorylation of these neuronal signaling molecules may result in cognitive memory decline.…”

“…Further phosphorylated and activated CREB-1 initiates the induction of immediate-early genes (especially Egr-1, C-fos, and C-jun) responsible for forming post-synaptic density proteins. Cumulative expression of these neuronal signaling proteins results in the LTM formation (Ganesh et al 2010;Rajan et al 2011;Ganesh et al 2012;Mendez et al 2015;Mukilan et al 2015;Mukilan et al 2018a;Thangaleela et al 2018;Mukilan 2023). This formed LTM is majorly impaired due to stress, gut-microbiota dysbiosis, and poor oral hygiene (Evans et al 2021;Lin et al 2021;Dai et al 2022;Mukilan 2023).…”

Effects of Probiotics, Prebiotics and Synbiotic Supplementation on Cognitive Impairment: A Review

“…The learning process is associated with activity-dependent changes and results in neurotransmitters' release (Lovinger 2010;Bai and Suzuki 2020). Neurotransmitter release results in the activation of neuronal signaling pathway with the help of several proteins like protein kinase A (PKA), extracellular signal-regulated kinase-1/2 (ERK-1/2), mitogen-activated protein kinase (MAPK), and cyclic AMP response element-binding protein-1 (CREB-1) (Yoon and Seger 2006;Ganesh et al 2010;Ganesh et al 2012;Mukilan et al 2015;García-Pardo et al 2016;Mukilan et al 2018aMukilan et al , 2018b. Activation of ERK-1/2 results in the phosphorylation of CREB-1 (Peng et al 2010).…”

“…Activation of ERK-1/2 results in the phosphorylation of CREB-1 (Peng et al 2010). Further, phosphorylated CREB-1 results in the activation of the immediate early gene (IEG) cascade and other postsynaptic density protein (PSD), which results in the formation of LTM (Ganesh et al 2010;Ganesh et al 2012;Mukilan et al 2015;Mukilan et al 2018aMukilan et al , 2018b.…”

“…paradigm(Ganesh et al 2010;Ganesh et al 2012;Mukilan et al 2015;Mukilan et al 2018a;Mukilan et al 2018b). Compared to the ERK cascade, BDNF is also involved in long-term memory formation.…”