Neuroscience
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Targeting reconsolidation with propranolol, a blocker of β-adrenergic receptors (β-ARs), emerged as a potential treatment for maladaptive memories such as those involved in posttraumatic stress disorder (PTSD). Reconsolidation targeting treatments for PTSD are becoming a common practice in the clinic and it is important to unveil any side effects upon 'non-targeted' memories. While previous studies have focused on propranolol's effects on the reconsolidation of emotional/distressful memories, the present study asked whether propranolol is involved in the reconsolidation of recognition memories - by assessing its effects on distinct memory components and the role of the dorsal hippocampus. ⋯ Propranolol infusions consistently impaired the addition of novel information to the previously consolidated memory trace regardless of dose, and the retention of familiar objects was not affected. Higher doses of propranolol also hindered memory of a familiar object that was not presented during the reactivation session, but was previously placed at the same location where novel information was presented during reactivation. The present results shed light on the role of β-ARs on the reconsolidation of different memory components and argue for the need for further studies examining possible recognition memory deficits following propranolol treatment.
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The unpredictable chronic mild stress (UCMS) model has been used to induce depressive-like symptoms in animal models, showing adequate predictive validity. Our work aims to evaluate the effects of environmental enrichment (EE) on resilience in this experimental model of depression. We also aim to assess changes in brain connectivity using cytochrome c oxidase histochemistry in cerebral regions related to cognitive-affective processes associated with depressive disorder: dorsal hippocampus, prefrontal cortex, amygdala, accumbens, and habenula nuclei. ⋯ EE induced a functional reorganization of brain activity. The EE + UCMS and UCMS groups showed different patterns of connections between brain regions. Our results showed that EE favors greater resilience and could reduce vulnerability to disorders such as depression and anxiety, modifying metabolic brain activity.
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Mitogen activated protein kinase interacting kinases (MNK) 1 and 2 are serine/threonine protein kinases that play an important role in translation of mRNAs through their phosphorylation of the RNA 5'-cap binding protein, eukaryotic translation initiation factor (eIF) 4E. These kinases are downstream targets for mitogen activated protein kinases (MAPKs), extracellular activity regulated protein kinase (ERK) and p38. MNKs have been implicated in the sensitization of peripheral nociceptors of the dorsal root and trigeminal ganglion (DRG and TG) using transgenic mouse lines and through the use of specific inhibitors of MNK1 and MNK2. ⋯ We sought to characterize mRNA expression in human DRG and TG (N = 3 ganglia for both DRG and TG) for both MNK1 and MNK2. Our results show that both genes are expressed by nearly all neurons in both human ganglia with expression in other cell types as well. Our findings provide evidence that MNK1 and MNK2 are expressed by human nociceptors of males and females and suggest that efforts to pharmacologically target MNKs for pain would likely be translatable due its conserved expression in both species.
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In mammals, adult neurogenesis was first demonstrated in the subventricular zone of the lateral ventricle (SVZ) and the dentate gyrus of the hippocampal formation. Further research showed that adult neurogenesis persists in other brain structures, such as the cerebral cortex, piriform cortex, striatum, amygdala, and hypothalamus. However, the origin of newly generated cells in these structures is not clear. ⋯ Based on comparative and functional approaches, we synthesize the knowledge of newly generated cells in the adult hypothalamus. The aim of this review is to provide new insights on adult neurogenesis in the mammalian hypothalamus, with particular attention given to marsupial species. We highlight the number of adult-born neurons in various hypothalamic nuclei, debating whether their low number has an impact on hypothalamic function.