Steroidogenic enzyme expression in estrogen production in the goat gastrointestinal (GI) tract and the effect of castration

Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function

Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.

New perspectives on the role of the neurosteroid pregnenolone as an endogenous regulator of type-1 cannabinoid receptor (CB1R) activity and function

Pregnenolone is a steroid with specific characteristics, being the first steroid to be synthesised from cholesterol at all sites of steroidogenesis, including the brain. For many years, pregnenolone was defined as an inactive precursor of all steroids because no specific target had been discovered. However, over the last decade, it has become a steroid of interest because it has been recognised as being a biomarker for brain-related disorders through the development of metabolomic approaches and advanced analytical methods. In addition, physiological roles for pregnenolone emerged when specific targets were discovered. In this review, we highlight the discovery of the selective interaction of pregnenolone with the type-1 cannabinoid receptor (CB1R). After describing the specific characteristic of CB1Rs, we discuss the newly discovered mechanisms of their regulation by pregnenolone. In particular, we describe the action of pregnenolone as a negative allosteric modulator and a specific signalling inhibitor of the CB1R. These particular characteristics of pregnenolone provide a great strategic opportunity for therapeutic development in CB1-related disorders. Finally, we outline new perspectives using innovative genetic tools for the discovery of original regulatory mechanisms of pregnenolone on CB1-related functions.

Estrogen synthesis in the stomach of Sprague-Dawley rats: comparison to Wistar rats

Aromatase, an estrogen synthase, exists in the gastric parietal cells of Wistar rats. The stomach synthesizes large amounts of estrogens and secretes them into the portal vein. We have been particularly studying gastric estrogen synthesis using Wistar rats. However, estrogen synthesis in the stomach of Sprague-Dawley (SD) rats, which are used as frequently as those of the Wistar strain, has not been clarified. We examined steroid synthesis in the stomach of SD rats using immunohistochemistry, in situ hybridization, Western blotting, real-time PCR, and LC-MS/MS. Aromatase also exists in the stomach of SD rats. Its distribution was not found to be different from that of Wistar rats. Results show that H+/K+-ATPase β-subunit and aromatase colocalized in double immunofluorescence staining. Each steroid synthase downstream from progesterone was present in the gastric mucosa. These results suggest that steroid hormones are synthesized in the parietal cells in the same pathway as Wistar rats. Although mRNA expression of steroid synthases were higher in SD, no significant difference was found in the amount of protein and each steroid hormone level in the portal vein. Although differences between strains might exist in steroid hormone synthesis, results show that SD rats are as useful as Wistar rats for gastric estrogen synthesis experimentation.

Cortisol, DHEA, and Sexual Steroid Concentrations in Fattening Pigs' Hair

Simple Summary

The rearing of heavy pigs in Italy is an important part of the production of Protected Designation of Origin (PDO) hams. Along with the standard quality characteristics, the quality of products with animal origin is also assessed by the level of animal welfare. Evaluation of hair steroid concentrations has been considered an effective approach to assess stress in mammals. The advantage of using hair for this process is that it provides an integrated measure of hormone concentrations over medium- and long-term periods, it can be simply and non-invasively collected, and it does not require any special expedient for storage. The aim of this study was to evaluate the hair cortisol, dehydroepiandrosterone (DHEA), and sexual steroid concentrations in fattening pigs at 36 weeks of age before slaughtering through a non-invasive approach. Females had significantly higher cortisol levels, significantly lower concentrations of DHEA, and significantly higher cortisol/DHEA ratios than barrows. Progesterone was significantly higher in gilts than in barrows. Testosterone and 17β-estradiol were significantly higher in barrows than in gilts. These results will allow us to plan future research with the aim of identifying threshold values in order to set up strategies to control the allostatic load and to increase the resilience of fattening pigs.

Abstract

The aim of this study was to analyze the feasibility and reliability of using hair as a matrix to determine the dehydroepiandrosterone (DHEA) and sexual steroid concentrations and the cortisol/DHEA ratio in fattening pigs. The results could be also used to plan future research to identify threshold values in order to set up strategies to control the allostatic load and increase the resilience of fattening pigs before slaughter. The study was conducted on 107 commercial crossbred rearing pigs. The hair samples were taken by shaving at the age of 36 weeks, and concentrations of the hormones were measured using a solid-phase microtiter radioimmunoassay. Females had significantly higher cortisol levels (p < 0.01), significantly lower DHEA concentrations (p < 0.05) and significantly higher cortisol/DHEA ratios (p < 0.01) than barrows. Progesterone was significantly higher in gilts than in barrows (p < 0.01). Testosterone and 17β-estradiol were significantly higher in barrows than in gilts (p < 0.05). If future research can produce threshold values for the different markers examined, the evaluation of animals under subclinical stress conditions will be possible.