Histology and Brain Derived Neurotrophic Factor immunoreaction of the neurons in the corpora quadrigemina of the African grasscutter (Thryonomys swinderianus – Temminck, 1827)

The African grasscutter is the second largest rodent in Africa, thus, a key component of the minilivestock industry. The study described the histological features and probed the distribution of Brain Derived Neurotrophic Factor (BDNF) in the corpora quadrigemina of the African grasscutter at foetal and postnatal developmental periods. Brain samples from foetuses explanted on foetal days 60 (F60) and 90 (F90) and extracted from 3 and 6-days-old pups (P3 and P6, respectively), 72-days-old juveniles (P72) and 450-days-old adults (P450) were used. They were prepared for histology and immunohistochemistry. Three laminae were distinct in the rostral colliculi at the foetal and postnatal periods; an outermost stratum zonale, middle stratum griseum superficiale and an inner stratum griseum profundum. Stratum griseum intermediale and stratum medullarium were not distinct. On F60 and F90, the stratum zonale was made of immature neurons, devoid of neurites; the central nucleus of the caudal colliculus was also made of immature migrating neurons. On P3, the neurons were already mature. The stratum zonale was made of medium-sized neuronal cells and thick processes. The thickness of this layer decreased with age. On P3, the caudal colliculus was made of all the components typical of a developed caudal colliculus. There was no BDNF immunoreactive cell in the stratum zonale at any postnatal period; a moderate BDNF-immunoreactivity in the stratum griseum superficiale on P3, a mild immunoreactivity on P6, none reactivity on P72 and mild on P450. The dorsal and lateral cortices of the caudal colliculus were none reactive to BDNF at any postnatal period. The results suggest a better auditory than visual capacity in the rodent.

Food restriction during lactation suppresses Kiss1 mRNA expression and kisspeptin-stimulated LH release in rats

Among the numerous physiological changes that accompany lactation is the suppression of the reproductive axis. The aim of this study was to investigate a possible role for the kisspeptin system in the restoration of the hypothalamic–pituitary–gonadal axis during late lactation in rats using a food restriction model that allows manipulation of the duration of lactational anovulation. Kiss1 mRNA expression and kisspeptin-immunoreactive cell counts were examined in both food-restricted dams and ad libitum (AL)-fed dams across late lactation when LH concentrations begin to increase. In the arcuate nucleus, Kiss1 mRNA expression and kisspeptin-positive cell counts were suppressed during late lactation. In the anteroventral periventricular (AVPV), day 15 food-restricted dams had significantly lower AVPV Kiss1 mRNA expression and a decreased LH response to exogenous kisspeptin compared with the AL-fed dams. Following 5 days of ad libitum food intake, these values were restored to levels similar to those in dams that had been fed ad libitum throughout lactation. In conclusion, this study shows that delayed restoration of the reproductive axis due to food restriction is associated with a decrease in kisspeptin sensitivity and low AVPV Kiss1 mRNA in late lactation.

Density of ghrelin-producing cells is higher in the gastric mucosa of morbidly obese patients

BackgroundGhrelin is a peptide mainly secreted by gastric mucosa and has been implicated in the regulation of eating behavior and weight balance. Obesity and Helicobacter pylori infection are associated with changes in plasma ghrelin levels.ObjectiveThis study was designed to evaluate the density of ghrelin-producing cells in the gastric mucosa of morbidly obese and dyspeptic non-obese patients, with and without H. pylori infection.MethodsGastric biopsies of the antral and oxyntic mucosa were obtained from 50 morbidly obese patients (BMI >40, 21 with metabolic syndrome (MS)), 17 dyspeptic overweight subjects (25<BMI<30), and 33 lean individuals (BMI<25) and processed for histology and immunohistochemistry.ResultsGhrelin-immunoreactive cell densities in the oxyntic mucosa were similar in morbidly obese patients with MS and in overweight and lean patients, whereas morbidly obese patients without MS presented higher ghrelin-immunoreactive cell density. The number of ghrelin cells in the oxyntic mucosa was significantly lower in obese and non-obese H. pylori-infected subjects. Ghrelin-immunoreactive cells, although sparse in the antral mucosa, were found more frequently in obese patients and their numbers did not seem to be affected by H. pylori infection.ConclusionsThe higher expression of ghrelin-immunoreactive cells in the oxyntic mucosa of morbidly obese patients compared with non-obese subjects or with morbidly obese subjects with MS and the finding of a higher number of small foci of ghrelin cells in the antral mucosa of obese patients may indicate an adaptive mechanism or an individual factor to be considered in the pathogenesis of obesity.