Attenuation of Corpus Callosum Axon Myelination and Remyelination in the Absence of Circulating Sex Hormones

Sex differences in the structure and organization of the corpus callosum (CC) can be attributed to genetic, hormonal or environmental effects, or a combination of these factors. To address the role of gonadal hormones on axon myelination, functional axon conduction and immunohistochemistry analysis of the CC in intact, gonadectomized and hormone‐replaced gonadectomized animals were used. These groups were subjected to cuprizone diet‐induced demyelination followed by remyelination. The myelinated component of callosal compound action potential was significantly decreased in ovariectomized and castrated animals under normal myelinating condition. Compared to gonadally intact cohorts, both gonadectomized groups displayed more severe demyelination and inhibited remyelination. Castration in males was more deleterious than ovariectomy in females. Callosal conduction in estradiol‐supplemented ovariectomized females was significantly increased during normal myelination, less attenuated during demyelination, and increased beyond placebo‐treated ovariectomized or intact female levels during remyelination. In castrated males, the non‐aromatizing steroid dihydrotestosterone was less efficient than testosterone and estradiol in restoring normal myelination/axon conduction and remyelination to levels of intact males. Furthermore, in both sexes, estradiol supplementation in gonadectomized groups increased the number of oligodendrocytes. These studies suggest an essential role of estradiol to promote efficient CC myelination and axon conduction in both sexes.     

Regulating emotion to improve physical health through the amygdala

The opinion of mind–body interaction has been increasingly acknowledged in recent years, as exemplified by accumulating evidence indicating that physical health (body) is associated with emotion and emotion regulation (mind). Yet, the neural basis linking emotion regulation with physical health remains largely uninvestigated. Here we used magnetic resonance imaging to investigate the neural basis of this pathway in a large population of healthy young adults. With a systematic study revealing the association of self-reported physical health and emotion traits of personality and general affective experiences, we further demonstrated that, for better physical health, individuals needed to regulate their emotion more effectively. Importantly, individuals who had larger gray matter (GM) volume in the amygdala reported not only a higher ability of emotion regulation but also better physical health. Further, GM volume in the amygdala mediated the correlation between emotion regulation ability and physical health. Our findings suggest that the amygdala plays a critical role in the neural circuit through which emotion regulation may influence physical health. Therefore, our study takes the first step toward exploring the neuroanatomical basis for body–mind interaction and may inform interventions aimed at promoting physical health by augmenting skills of emotion regulation.     

A new method for measurement of blood flow,pH, and transmucosal potential difference in rat gastroduodenal mucosa by endoscopy

A method was developed to measure the mucosal blood flow (BF), mucosal pH (pH), and transmucosal potential difference (PD) in various sites from the oral cavity to the duodenum without surgical operation or damage to the subject rats. These measurements were carried out by using three indicator electrodes, which were attached to the various sites through the suction channel of an endoscope. The hydrogen gas clearance method was used for the measurement of BF. BF values obtained at the fundic, pyloric, and duodenal regions were 119±17, 69.9±8.8, and 114±18 ml/min/100 g (mean±se), respectively. The pH values were lowest at the cardiac portion and the forestomach and highest at the duodenum. PD showed higher values at the stomach and lower values at the pharynx and duodenum. Using this technique, it was possible to measure the BF, pH, and PD repeatedly and safely at various sites in the same rat. Therefore, it was suggested that this method is useful in studying the physiological functions of the stomach and duodenum and the pathogenesis of gastroduodenal ulceration and that this method is applicable to measure the change of the above parameters in the healing process of gastric ulcer in rats.     

Fundoplication for gastroesophageal reflux disease: regional variability and factors predicting operative approach

We have recently shown that the majority of patients undergoing fundoplication in the United States are women. Based on these findings, we hypothesized that nonbiological factors contribute to the decisions on surgical reflux therapy. Using State Inpatient Databases of the Agency for Healthcare Research and Quality, we extracted annual fundoplication rates, sex distribution, age cohorts, racial background, and insurance coverage. To account for potential differences in state populations, the results were normalized and correlated with Census data, adult obesity rates, median income, poverty rates, and physician workforce within the state. Fundoplication rates varied fivefold between states, ranging from 4.1 ± 0.1 per 100 000 in New Jersey to 21.8 ± 0.4 per 100 000 in Oregon. Higher poverty rates and a higher fraction of Caucasians within a state independently predicted higher fundoplication rates. While the majority of operations were performed laparoscopically, surgical approaches also differed between states with rates of laparoscopic ranging from 52.3 ± 1.8% in Oklahoma to 87.4 ± 1.7% in Hawaii. A lower number of pediatric and Medicaid‐insured patient and a higher fraction of privately insured patients best predicted higher rates of laparoscopic surgery. Our study shows significant regional variation in surgical reflux management, which cannot be explained by differences in disease mechanisms. Insurance coverage and racial background influenced the likelihood of surgery, suggesting a role of financial incentives.