Neuroscience
-
Cortical spreading depolarization (CSD) is the electrophysiological substrate of migraine aura, and a putative trigger of trigeminovascular activation and migraine headache. Many migraineurs report stress or relief after a stress triggers an attack. We tested whether various stress conditions might modulate CSD susceptibility and whether this is dependent on genetic factors. ⋯ Stress status did not affect CSD propagation speed, duration or amplitude. In summary, relief after chronic stress, but not acute or chronic stress alone, augments CSD in genetically susceptible mice. Therefore, enhanced CSD susceptibility may explain why, in certain patients, migraine attacks typically occur during a period of stress relief such as weekends or holidays.
-
Addiction to prescribed opioids including oxycodone has reached tragic levels. Herein, we investigated the relevance of fibroblast growth factors (FGFs) and immediate early genes (IEGs) to withdrawal-induced incubation of drug craving following escalated oxycodone self-administration (SA). Rats were trained to self-administer oxycodone for 4 weeks. ⋯ Similarly, striatal c-fos and junB mRNA levels showed greater increases in LgA rats. The observations that fgf mRNA levels were more altered in the dorsal striatum than in the NAc of LgA rats suggest that changes in striatal FGF expression may be more salient to incubation of oxycodone craving than alterations in the NAc. Targeting FGF signaling pathways might offer novel strategies against opioid addiction.
-
Exposure to commonly used anesthetics is associated with widespread neuroapoptosis in neonatal animals. Vulnerability of developing hippocampal dentate gyrus granule cells to anesthetic neurotoxicity peaks approximately 2 weeks after cell birth, as measured by bromodeoxyuridine birth dating, regardless of the age of the animal. The present study examined whether the vulnerable window can be further characterized by utilizing a transgenic approach. ⋯ Apoptotic EGFP- granule cells more frequently expressed the immature neuronal marker calretinin (75.4% vs 45.0%, P < 0.001) and less frequently the late progenitor marker NeuroD1 (21.9% vs 87.9%, P < 0.001) than EGFP+ granule cells. Although EGFP- granule cells were more mature in immunostaining than EGFP+ granule cells, their electrophysiological properties partially overlapped in terms of input resistance, resting membrane potential and action potential amplitude. Our results revealed the POMC stage, when GABA acts as an excitatory neurotransmitter, only partly captures susceptibility to anesthetic neurotoxicity, suggesting the vulnerable window of anesthesia-induced neuroapoptosis extends from the end of POMC+ stage to the post-POMC+ stage when depolarizing glutamatergic inputs emerge.
-
Temporal lobe epilepsy is triggered by an initial insult, such as status epilepticus, that initiates the process of epilepsy development. Heat shock protein 70 (Hsp70) is a ubiquitously expressed molecular chaperone, involved in the inflammatory response that is upregulated after status epilepticus. Hsp70 has been described as an endogenous intracellular ligand of Toll-like receptor 4. ⋯ No colocalization with the astrocytic marker GFAP or the microglia marker Iba1 was found. The intense neuronal Hsp70 upregulation during the early post-insult phase might contribute to the onset of excessive inflammation triggering molecular and cellular reorganization and generation of a hyperexcitable epileptic network. Therefore, development of multi-targeting strategies aiming at prevention of epileptogenesis should consider Hsp70 modulation in the early days following an epileptogenic insult.
-
Hypoxia inducible factor-1α (HIF-1α) is a key transcription factor that maintains oxygen homeostasis. Hypoxic stress is related to the pathogenesis of amyotrophic lateral sclerosis (ALS), and impaired HIF-1α induces motor neuron degeneration in ALS. Dimethyloxalylglycine (DMOG) upregulates the stability of HIF-1α expression and shows neuroprotective effects, but has not been used in ALS as an anti-hypoxic stress treatment. ⋯ DMOG treatment significantly ameliorated the decrease in HIF-1α expression, the degeneration of both spinal motor neurons and myofibers in lower limbs, gliosis and apoptosis in the spinal cord. This was accompanied by prolonged survival. The present study suggests that in vivo bioluminescence resonance energy transfer (BRET) HIF-1α imaging is useful for evaluating hypoxic stress in ALS, and that the enhancement of HIF-1α is a therapeutic target for ALS patients.