Autophagy regulates the release of exercise factors and their beneficial effects on spatial memory recall

Exercise promotes learning and memory recall as well as rescues cognitive decline associated with aging. The positive effects of exercise are mediated by circulatory factors that predominantly increase Brain Derived Neurotrophic Factor (BDNF) signaling in the hippocampus. Identifying the pathways that regulate the release of the circulatory factors by various tissues during exercise and that mediate hippocampal Mus musculus Bdnf expression will allow us to harness the therapeutic potential of exercise. Here, we report that two weeks of voluntary exercise in male mice activates autophagy in the hippocampus by increasing LC3B protein levels (p = 0.0425) and that autophagy is necessary for exercise-induced spatial learning and memory retention (p < 0.001; exercise + autophagy inhibitor chloroquine CQ versus exercise). We place autophagy downstream of hippocampal BDNF signaling and identify a positive feedback activation between the pathways. We also assess whether the modulation of autophagy outside the nervous system is involved in mediating exercise's effect on learning and memory recall. Indeed, plasma collected from young exercise mice promote spatial learning (p = 0.0446; exercise versus sedentary plasma) and memory retention in aged inactive mice (p = 0.0303; exercise versus sedentary plasma), whereas plasma collected from young exercise mice that received the autophagy inhibitor chloroquine diphosphate failed to do so. We show that the release of exercise factors that reverse the symptoms of aging into the circulation is dependent on the activation of autophagy in young animals. Indeed, we show that the release of the exercise factor, beta-hydroxybutyrate (DBHB), into the circulation, is autophagy-dependent and that DBHB promotes spatial learning and memory formation (p = 0.0005) by inducing hippocampal autophagy (p = 0.0479). These results implicate autophagy in peripheral tissues and in the hippocampus in mediating the effects of exercise on learning and memory recall and identify DBHB as a candidate endogenous exercise factor whose release and positive effects are autophagy-dependent.

Exercise and Dietary Factors Mediate Neural Plasticity Through Modulation of BDNF Signaling

The term “neural plasticity” was first used to describe non-pathological changes in neuronal structure. Today, it is generally accepted that the brain is a dynamic system whose morphology and function is influenced by a variety of factors including stress, diet, and exercise. Neural plasticity involves learning and memory, the synthesis of new neurons, the repair of damaged connections, and several other compensatory mechanisms. It is altered in neurodegenerative disorders and following damage to the central or peripheral nervous system. Understanding the mechanisms that regulate neural plasticity in both healthy and diseased states is of significant importance to promote cognition and develop rehabilitation techniques for functional recovery after injury. In this minireview, we will discuss the mechanisms by which environmental factors promote neural plasticity with a focus on exercise- and diet-induced factors. We will highlight the known circulatory factors that are released in response to exercise and discuss how all factors activate pathways that converge in part on the activation of BDNF signaling. We propose to harness the therapeutic potential of exercise by using BDNF as a biomarker to identify novel endogenous factors that promote neural plasticity. We also discuss the importance of combining exercise factors with dietary factors to develop a lifestyle pill for patients afflicted by CNS disorders.

Peripheral insulin and brain structure in early Alzheimer disease

OBJECTIVE

Accumulating evidence suggests insulin and insulin signaling may be involved in the pathophysiology of Alzheimer disease (AD). The relationship between insulin-mediated glucoregulation and brain structure has not been assessed in individuals with AD.

METHODS

Nondemented (Clinical Dementia Rating [CDR] 0, n = 31) and early stage AD (CDR 0.5 and 1, n = 31) participants aged 65 years and older had brain MRI to determine whole brain and hippocampal volume and 3-hour IV glucose tolerance tests to determine glucose and insulin area under the curve (AUC). Linear regression models were used to assess the relationship of insulin and glucose with brain volume, cognition, and dementia severity.

RESULTS

In early AD, insulin and glucose AUCs were related to whole brain (insulin beta = 0.66, p < 0.001; glucose beta = 0.45, p < 0.01) and hippocampal volume (insulin beta = 0.42, p < 0.05; glucose beta = 0.46, p < 0.05). These relationships were independent of age, sex, body mass index, body fat, cardiorespiratory fitness, physical activity, cholesterol, and triglycerides. Insulin AUC, but not glucose, was associated with cognitive performance in early AD (beta = 0.40, p = 0.04). Insulin AUC was associated with dementia severity (Pearson r = -0.40, p = 0.03). Glucose and insulin were not related to brain volume or cognitive performance in nondemented individuals.

CONCLUSIONS

Increased peripheral insulin is associated with reduced Alzheimer disease (AD)-related brain atrophy, cognitive dysfunction, and dementia severity, suggesting that insulin signaling may play a role in the pathophysiology of AD.

[Branchial paraganglioma. A case of carotid paraganglioma and review of the literature]

We report the case of a 58-year-old man hospitalized for generalized seizures. A grade II glioma of the left frontotemporal region was diagnosed on brain CT scan and stereotaxic biopsy results. Radiotherapy was successful in treating this glioma. A glomus tumor of the left carotid was discovered by duplex Doppler examination of the carotid and confirmed on arteriography. Resection was performed to the adventitia. Branchial glomus tumors are rare, often benign tumors. The carotid is a common localization. Surgery is often indicated due to the risk of local invasion. Surgical procedure varies according to the size and localization of the tumor. This case demonstrates that glomus tumor of the carotid can coexist with a frontotemporal glioma.

Pentigetide nasal solution: a multicenter study evaluating efficacy and safety in patients with seasonal allergic rhinitis

The safety and efficacy of pentigetide (Pentyde) nasal solution, administered as 1 mg into each nostril four times daily, was compared with placebo for controlling symptoms associated with seasonal allergic rhinitis. This was a randomized, multicenter, double-blind, parallel-group trial involving 431 patients divided equally between pentigetide and placebo treatment. The study was conducted during the 1986 spring allergy season and consisted of 1 week of baseline followed by 2 weeks of treatment. Physicians evaluated the frequency and severity of nasal symptoms at study entry (day 1) and the final visit (day 22). Physicians and patients assessed the global condition of the patient at the end of the study and patients also recorded the severity of symptoms in a daily diary. Pentigetide-treated patients showed a statistically significant greater reduction in the frequency (P = .004) and severity (P = .05) of total nasal symptom score (sneezing, nasal congestion, and rhinorrhea) and in the individual nasal symptom scores compared with placebo-treated patients. Diary results showed consistently lower total nasal symptom scores on each treatment day for pentigetide-treated patients (P = .02). Both the physicians and patients globally rated more pentigetide-treated patients improved than placebo-treated patients. The incidence and types of adverse experiences were similar between treatment groups and there were no reports of sedation or fatigue in the pentigetide group. No clinically significant changes occurred for laboratory tests, physical examination parameters or vital sign measurements. Pentigetide nasal solution was safe and effective for the treatment of seasonal allergic rhinitis.

Doubling time and annual doubling rate of human prostatic cancer

The doubling time (DT) of human prostatic cancer is calculated for the first time; its various parameters and the relative importance of each are reviewed. A crude volume-doubling time (DTcv), a theoretical doubling of the number of cells (DTt), and an annual doubling rate (ADR), are defined and calculated for each of 12 patients who had undergone needling of the prostate for diagnostic purposes and in whom tumor cells were implanted in the track of the biopsy needle and had grown into a subcutaneous perineal nodule. The harmonic average DTcv was six days and DTt eight days, and the average ADR was 45 doublings per year. From the study of the calculated DTs and ADRs, it became obvious that the 12 patients fell into three distinct groups: Group I = slow tumor growth rate, an average ADR of 9 doublings per year, and a harmonic average DTt of forty days; Group II = medium tumor growth rate, an average ADR of 35 doublings/year, and a harmonic average DTt of ten days; and Group III = rapid tumor growth rate, an average ADR of 100 doublings/year, and a harmonic average DTt of four days.