This study reports the effects of aqueous extracts obtained from three fern species of Bulgarian origin: Asplenium ceterach L., Asplenium scolopendrium L., and Asplenium trichomanes L. on the contractility and bioelectrogenesis of rat gastric smooth muscle tissues. In the concentration range 0.015–0.150 mg/mL the three extracts contracted smooth muscle tissues in a concentration-dependent manner. The contractions caused by A. ceterach L. and A. scolopendrium L. extracts (0.150 mg/mL) were reduced by ketanserin (5 × 10 −7 and 5 × 10 −6 mol/L), an antagonist of serotonin 5-HT2 receptor. The contraction evoked by A. trichomanes L. (0.150 mg/mL) was significantly reduced by 1 × 10 −6 mol/L atropine, an antagonist of muscarinic receptors, and turned into relaxation against the background of 3 × 10 −7 mol/L galantamine. After combined pretreatment with galantamine and l -arginine (5 × 10 −4 mol/L), this relaxation become more pronounced. The study demonstrates that constituents of A. ceterach L. and A. scolopendrium L. extracts act as agonists of 5-HT2 receptors and cause contraction by activating serotonergic signaling system. A. trichomanes L.-induced reaction is an additive result of two opposite-in-character effects. The dominant contraction is initiated by inhibition of acetylcholinesterase activity. The relaxation develops with pre-inhibited acetylcholinesterase, it is significantly potentiated by l -arginine, and therefore associated with nitrergic signaling pathway.

The use of dietary supplements (DSs) has dramatically increased in recent decades. However, around 20% of these products are reported to contain pharmacologically active undeclared compounds, most of which could expose consumers to serious side effects. According to recent data, some of the most commonly detected undeclared compounds are also considered doping and are prohibited by the World Anti-Doping Agency (WADA). One of the most frequently detected undeclared substances in DSs used for promoting weight loss is sibutramine. In 2011, all medicines containing sibutramine were urgently withdrawn from Europe and US markets because of serious side effects. In the present study, in order to detect and quantify sibutramine in DSs, a rapid, sensitive, and reliable gas chromatography with mass spectrometry (GC-MS) method was developed. The method was validated according to the ICH guidelines and demonstrated good linearity, accuracy, precision, and robustness. The limits of detection and quantification were 0.181 μg/mL and 0.5488 μg/mL, respectively. The method was applied to analyze 50 DSs promoting weight loss, fat burning, and performance enhancement. Sibutramine was detected in six of them in a range of 16.59–14,854.94 μg/per capsule. The high concentrations of sibutramine detected in some samples raise concerns about the potential health risks associated with the use of adulterated DSs. The proposed GC-MS method could be used successfully in the quality control of DSs or in different research programs, contributing to safety and the prevention of associated side effects.

Phytoecdysteroids (PEs) are naturally occurring steroid compounds, that have recently gained significant attention, due to their diverse biological activities and high therapeutic potential. The aim of the present study was to quantify some PEs including 20-hydroxyecdysterone (20-HE), ponasterone A (PA), and turkesterone (TU) in selected plant foods and Rhaponticum carthamoides extract. Furthermore, the effects of 20-HE, TU, and R. carthamoides extract, were investigated with in vitro methods using isolated smooth muscle tissues. The levels of 20-HE in the analyzed samples exhibited significant differences, with kaniwa seed extract containing the highest amount, followed by spinach leaf extract, quinoa seed extract, and asparagus stem extract. The in vitro analyses suggested that R. carthamoides extract exhibits dose-dependent cytotoxic effects on smooth muscle cells, with low doses promoting contraction and higher doses inducing relaxation. Additionally, the extract demonstrated a significant inhibitory effect on ACh-induced contractions, while 20-HE enhanced the contractile response. The current findings highlighted phytoecdysteroids’ potential for modifying gastrointestinal motility.

The influence of accelerated electrons on neuronal structures is scarcely explored compared to gamma and X-rays. This study aims to investigate the effects of accelerated electron radiation on some pivotal neurotransmitter circuits (cholinergic and serotonergic) of rats’ myenteric plexus. Male Wistar rats were irradiated with an electron beam (9 MeV, 5 Gy) generated by a multimodality linear accelerator. The contractile activity of isolated smooth muscle samples from the gastric corpus was measured. Furthermore, an electrical stimulation (200 μs, 20 Hz, 50 s, 60 V) was performed on the samples and an assessment of the cholinergic and serotonergic circuits was made. Five days after irradiation, the recorded mechanical responses were biphasic—contraction/relaxation in controls and contraction/contraction in irradiated samples. The nature of the contractile phase of control samples was cholinergic with serotonin involvement. The relaxation phase involved ACh-induced nitric oxide release from gastric neurons. There was a significant increase in serotonergic involvement during the first and second contractile phases of the irradiated samples, along with a diminished role of acetylcholine in the first phase. This study demonstrates an increased involvement of serotonergic neurotransmitter circuits in the gastric myenteric plexus caused by radiation with accelerated electrons.

Accelerated electron beam, gastric smooth muscles, contractile activity, 5-НТ

Ionizing radiation in radiotherapy can disrupt cellular functions based on radiation type, energy, and dose. However, investigations on the effects of accelerated electrons, particularly on serotonin mediation, are limited. This study aimed to investigate changes in serotonin signal transduction (targeting 5-HT_2A and 5-HT_2B receptors) in gastric smooth muscle (SM) samples isolated from rats irradiated with accelerated electrons (linear accelerator Siemens Primus S/N 3561) and their effects on serotonin-induced reactions. The radiation effects were examined in samples prepared five days after the procedure. The contractile activity of smooth muscle samples was measured using an isometric method. The expression of 5-HT_2A and 5-HT_2B receptors was determined by immunohistochemical assay. Increased contractile reactivity to exogenous serotonin (1.10⁻⁸–1.10⁻⁴ mol/L) was observed in irradiated samples compared to controls. The expression of 5-HT_2A and 5-HT_2B receptors was significantly increased in the irradiated tissue. By selecting appropriate time intervals between equimolar (1.10⁻⁶ mol/L) sequential serotonin exposures, a process of desensitization associated with agonist-induced internalization was established in control samples, which was absent in irradiated samples. In conclusion, irradiation with accelerated electrons affects the agonist-induced receptor internalization of 5-HT_2A and 5-HT_2B receptors and increases their expression in rat gastric SM, which alters their contractile reactivity to exogenous serotonin.