A novel method for olfactory bulbectomy using photochemically induced lesion

Increased Resting-State Functional Connectivity of the Hippocampus in Rats With Sepsis-Associated Encephalopathy

Background

Sepsis-associated encephalopathy (SAE) has been identified as a frequent complication of sepsis, featured by an aberrant level of cognitive and affective functions. The present study is designed to explore the changes in functional connectivity (FC) of the hippocampus in rats with SAE utilizing resting-state functional magnetic resonance imaging (rs-fMRI).

Methods

Sprague-Dawley rats were randomly assigned to the SAE and control groups. We acquired rs-fMRI data using a 7T MRI to evaluate hippocampal network functional differences between the two groups with a seed-based approach. Behavioral performance was assessed using the open field test and forced swimming test. Statistical analysis was undertaken to evaluate the correlation between the hippocampal FC and behavioral findings.

Results

Compared with the control group, the SAE group showed increased FC between the bilateral hippocampus and thalamus, septum, bed nuclei stria terminalis (BNST), left primary forelimb somatosensory cortex (S1FL), primary motor cortex (M1), and inferior colliculus. Increased FC between the left hippocampus and thalamus, septum, BNST, left S1FL, and inferior colliculus was observed. While with the right hippocampus, FC in thalamus, septum, left S1FL and inferior colliculus was enhanced. Additionally, positive correlations were found between the hippocampal FC and the immobility time in the forced swimming test.

Conclusion

Hippocampus-related brain networks have significant alterations in rats with SAE, and the elevated hippocampal resting-state FC was positively related to affective deficits. Changes in FC between the hippocampus and other brain regions could be a potential neuroimaging biomarker of cognitive or mental disorders triggered by SAE.

The Medial Septum as a Potential Target for Treating Brain Disorders Associated With Oscillopathies

The medial septum (MS), as part of the basal forebrain, supports many physiological functions, from sensorimotor integration to cognition. With often reciprocal connections with a broad set of peers at all major divisions of the brain, the MS orchestrates oscillatory neuronal activities throughout the brain. These oscillations are critical in generating sensory and emotional salience, locomotion, maintaining mood, supporting innate anxiety, and governing learning and memory. Accumulating evidence points out that the physiological oscillations under septal influence are frequently disrupted or altered in pathological conditions. Therefore, the MS may be a potential target for treating neurological and psychiatric disorders with abnormal oscillations (oscillopathies) to restore healthy patterns or erase undesired ones. Recent studies have revealed that the patterned stimulation of the MS alleviates symptoms of epilepsy. We discuss here that stimulus timing is a critical determinant of treatment efficacy on multiple time scales. On-demand stimulation may dramatically reduce side effects by not interfering with normal physiological functions. A precise pattern-matched stimulation through adaptive timing governed by the ongoing oscillations is essential to effectively terminate pathological oscillations. The time-targeted strategy for the MS stimulation may provide an effective way of treating multiple disorders including Alzheimer's disease, anxiety/fear, schizophrenia, and depression, as well as pain.

Modulation of musculoskeletal hyperalgesia by brown adipose tissue activity in mice

Cold exposure and a variety of types of mild stress increase pain in patients with painful disorders such as fibromyalgia syndrome. Acutely, stress induces thermogenesis by increasing sympathetic activation of beta-3 (β3) adrenergic receptors in brown adipose tissue. Chronic stress leads to the hypertrophy of brown adipose, a phenomenon termed adaptive thermogenesis. Based on the innervation of skeletal muscle by collaterals of nerves projecting to brown adipose, we theorized an association between brown adipose tissue activity and musculoskeletal hyperalgesia and tested this hypothesis in mice. Exposure to a cold swim or injection of BRL37344 (β3 adrenergic agonist) each enhanced musculoskeletal hyperalgesia, as indicated by morphine-sensitive decreases in grip force responses, whereas SR59230A (β3 adrenergic antagonist) attenuated swim-induced hyperalgesia. Chemical ablation of interscapular brown adipose, using Rose Bengal, attenuated the development of hyperalgesia in response to either swim stress or BRL37344. In addition, elimination of the gene expressing uncoupling protein-1 (UCP1), the enzyme responsible for thermogenesis, prevented musculoskeletal hyperalgesia in response to either a swim or BRL37344, as documented in UCP1-knockout (UCP1-KO) mice compared with wild-type controls. Together, these data provide a convergence of evidence suggesting that activation of brown adipose contributes to stress-induced musculoskeletal hyperalgesia.

Related expressional change of HIF-1α to the neuroprotective activity of exendin-4 in transient global ischemia

Transient global ischemia induces selective hippocampal pyramidal neuronal death. Under conditions of severe ischemic hypoxia, hypoxia-inducible factor-1α (HIF-1α) induces apoptosis. Exendin-4 (Ex-4), the glucagon-like peptide-1 receptor (GLP-1R) agonist, provides neuroprotection against brain damage after cerebral ischemia. We investigated the relationship between Ex-4 and HIF-1α by examining Ex-4-induced changes in HIF-1α expression in the gerbil hippocampus following global brain ischemia (in vivo) and in neuroblastoma cells (SH-SY5Y) and cortical primary neurons (in vitro). Twice-daily administration of Ex-4 (1 μg/kg) for 3 days after ischemia (30 min before and 30 min after ischemia on the day of surgery and 2 more days) decreased the number of Fluoro-Jade B-stained cells in the CA1 pyramidal region of the hippocampus of the ischemic brain. Western blot analysis indicated a significant decrease in HIF-1α expression in the ischemic compared with the Sham brain following Ex-4 treatment. These in-vivo results were confirmed in vitro in SH-SY5Y cells and primary cortical neurons treated with 100 nM of Ex-4 under hypoxic conditions (0.1%>O2). We found that Ex-4 decreased the HIF-1α expression in the SH-SY5Y cell line and primary cortical neurons under hypoxic conditions, and this effect was reversed by cotreatment with exendin (9-39), a GLP-1R antagonist. These results suggest that HIF-1α may be involved in the neuroprotective effect of Ex-4 in the hypoxia-damaged brain.

A novel animal model for studying pancreatic regeneration by employing photochemical reaction

PURPOSE

We present photochemical-induced pancreatic necrosis (PIPN) as a novel induction method for studying pancreatic regeneration in an animal model.

METHODS

Photosensitive Rose Bengal was injected through the femoral vein in rats, followed by illumination of the surface of the pancreas with a cool halogen light for a period of 20 min. At 3, 6, and 24 h, and 7, 10, 14, and 20 days, experimental animals were sacrificed; all the animals received intravenous injection with 5-bromo-2-deoxyuridine (BrdU) 1 h prior to sacrifice.

RESULTS

At 3-6 h of induction of PIPN, pancreatic necrosis was superficially observed in the illuminated field. At 24 h, there was a slight increase in the depth and width of the lesion along with appearance of vascular congestion and thrombosis in the lesion. On days 7-10, the area of illumination was totally replaced by necrotic pancreatic tissue, inflammatory cell infiltrates, and newly appearing cellular components, including mesenchymal and epithelial cells, which formed tubular complexes. On day 14, clusters of tubular complexes intermingled with acinar cells, which were proven as newly formed acinar tissue by BrdU staining. On day 20, all the lesions had returned to a normal state of pancreatic tissue.

CONCLUSION

This study demonstrates the potential of PIPN as a valuable method for production of an animal model for studying healing processes or regeneration of pancreatic tissue after injury.