Cannabinoid and Serotonergic Systems: Unraveling the Pathogenetic Mechanisms of Stress-Induced Analgesia.

The perception of "stress" triggers many physiological and behavioral responses, collectively called the stress response. Such a complex process allows for coping with stress and also triggers severe pathology. Because of the multidirectional effect of stress on the body, multiple systems participate in its pathogenesis, with the endogenous cannabinoid and the serotoninergic ones among them. These two systems also take part in the pain perception decrease, known as stress-induced analgesia (SIA), which can then be taken as an indirect indicator of the stress response. The aim of our study was to study the changes in cold SIA (c-SIA) resulting from the exogenous activation of cannabinoid receptor type 1 (CB1) and 5-hydroxytryptamine (5-HT, serotonin) receptor type 1A (5-HT1A). Various combinations of agonists and/or antagonists of CB1 and 5-HT1A, before or after 1 h of cold exposure, were applied, since we presumed that the exogenous activation of the receptors before the cold exposure would influence the pathogenesis of the stress response, while their activation after the stressful trigger would influence the later development. Our results show that the serotonergic system "maintained" c-SIA in the pre-stress treatment, while the cannabinoids' modulative effect was more prominent in the post-stress treatment. Here, we show the interactions of the two systems in the stress response. The interpretation and understanding of the mechanisms of interaction between CB1 and 5-HT1A may provide information for the prevention and control of adverse stress effects, as well as suggest interesting directions for the development of targeted interventions for the control of specific body responses.

Synthesis, Hydrolytic Stability and In Vivo Biological Study of Bioconjugates of the Tetrapeptides FELL Containing Pyrrole Moiety.

BACKGROUND: Bioconjugates are promising alternatives for the multiple targeting of any disease. Pyrrole heterocycle is well known with many activities and is a building block of a lot of medical drugs. On the other hand, peptides are short molecules with many advantages such as small size, ability to penetrate the cell membrane and bond-specific receptors, vectorizing potential, etc. Thus, hybrid molecules between peptide and pyrrole moiety could be a promising alternative as an anti-pain tool. METHODS: New bioconjugates with a general formula Pyrrole (α-/ß-acid)-FELL-OH (NH2) were synthesized using Fmoc/OtBu peptide synthesis on solid support. HPLC was used to monitor the purity of newly synthesized bioconjugates. Their structures were proven by electrospray ionization mass spectrometry. The Paw Pressure test (Randall-Selitto test) was used to examinate the analgesic activity. Hydrolytic stability of targeted structures was monitored in three model systems with pH 2.0, 7.4 and 9.0, including specific enzymes by means of the HPLC-UV method. RESULTS: The obtained results reveal that all newly synthesized bioconjugates have analgesic activity according to the used test but free pyrrole acids have the best analgesic activity. CONCLUSIONS: Although free pyrrole acids showed the best analgesic activity, they are the most unstable for hydrolysis. Combination with peptide structure leads to the hydrolytic stabilization of the bioconjugates, albeit with slightly reduced activity.

Synthesis, In Silico Logp Study, and In Vitro Analgesic Activity of Analogs of Tetrapeptide FELL.

BACKGROUND: The inflammatory process represents a specific response of the organism's immune system. More often, it is related to the rising pain in the affected area. Independently of its origin, pain represents a complex and multidimensional acute or chronic subjective unpleasant perception. Currently, medical doctors prescribe various analgesics for pain treatment, but unfortunately, many of them have adverse effects or are not strong enough to suppress the pain. Thus, the search for new pain-relieving medical drugs continues. METHODS: New tetrapeptide analogs of FELL with a generaanalgesic-Glu-X3-X4-Z, where X = Nle, Ile, or Val and Z = NH2 or COOH, containing different hydrophobic amino acids at positions 3 and 4, were synthesized by means of standard solid-phase peptide synthesis using the Fmoc/OtBu strategy in order to study the influence of structure and hydrophobicity on the analgesic activity. The purity of all compounds was monitored by HPLC, and their structures were proven by ESI-MS. Logp values (partition coefficient in octanol/water) for FELL analogs were calculated. Analgesic activity was examined by the Paw-pressure test (Randall-Selitto test). RESULTS: The obtained results reveal that Leu is the best choice as a hydrophobic amino acid in the FELL structure. CONCLUSIONS: The best analgesic activity is found in the parent compound FELL and its C-terminal amide analog.

The Endogenous Cannabinoid and the Nitricoxidergic Systems in the Modulation of Stress Responses.

The effects on stress-induced analgesia (SIA) from endogenous cannabinoid system (ECS) and nitric oxide (NO) interaction after 1 h of restraint stress were evaluated in male Wistar rats. The animals were subjected to 1 h of restraint and then injected with different combinations of cannabinoid receptor type 1 agonist anandamide (AEA) or antagonist AM251 along with an NO donor, NO precursor, or inhibitor of NO synthase. Nociception was evaluated using paw pressure (PP) or hot plate (HP) tests. AEA was administered immediately after the end of restraint-SIA (r-SIA). Administration of NO precursor reversed the pronociceptive effect of the CB1 agonist on r-SIA. Both the CB1 antagonist and the NOS inhibitor neutralized the pro-analgesic effect of L-arginine (L-arg). Administration of an NO donor, instead, increased r-SIA. Our experiments confirmed that the endogenous cannabinoid and the NO-ergic systems interact in the modulation of r-SIA. This interaction probably implies NO as a second messenger of the ECS.

Butane-induced acute global myocardial ischemia without coronary artery pathology.

The case report describes a case of acute myocardial ischemia precipitated by propane butane inhalation. The dependency of this substance around the world is still moderate but is increasing due to the easy availability of the substance and the facility with which the effects can be concealed. The toxicity of the substance is significant; affecting the heart, the brain and the liver. The most common outcome is sudden death. In this article, we describe a survivor after an episode of acute poisoning and his interesting cardiac pathology.

[Comparative Clinical and Ultrastructural Analysis of the Results from Ranibizumab and Aflibercept in Patients with PDR]. / Ultrastruktureller und klinischer Vergleich des Ergebnisses bei PDR-Patienten, behandelt mit Ranibizumab oder Aflibercept ­ von Grundlagenforschungen zu den klinischen Therapien.

PURPOSE: Diabetic retinopathy is one of the worst complications of diabetes and can threaten sight. The aim of our study is to compare the clinical outcomes and ultrastructural changes in diabetic retinopathy patients after intravitreal admission of either ranibizumab (Lucentis) or aflibercept (Eylea). METHODS: In our prospective study, 27 patients with PDR were enrolled. They were divided into two groups - 14 PDR patients treated with ranibizumab and 13 PDR patients treated with aflibercept. In both groups, a complete ophthalmological examination was performed, including OCT. In 12 patients (6 from each group), pars plana vitrectomy was performed with excision of epiretinal membranes. Transmission and scanning electron microscopy of the membranes was performed. RESULTS: Clinical findings - in both groups there was a decrease in the neovascular proliferation and macular oedema. CRT was reduced with approximately 100 - 120мk. In the Eylea group, there was general shrinking of neovascular proliferation with lower risk of bleeding. The ultrastructural analysis showed more significant reduction in endothelial fenestration after Eylea application, with clustering of platelets and erythrocytes in the capillary lumen. Increased numbers of macrophages were found in the membranes of both groups. CONCLUSION: Our results show that aflibercept is very effective in treating PDR. It causes more significant reduction of endothelial fenestration and more evident thrombotic microangiopathy than other anti-VEGF drugs, and thus diminishes macular oedema and prevents neovascular tissue from bleeding. Eylea inhibits both VEGF and placental growth factor and thus modifies the whole pathophysiology of DR. It is therefore more effective than other treatment medications.

Synthesis and analgesic effects of novel ß2-tryptophan hexapeptide analogs.

Aiming to develop more potent analgesic substances a new series of hexapeptides containing ß(2)-tryptophan analogues was synthesized. The Trp in position 4 and 5, respectively in Ac-Arg-Phe-Met-Trp-Met-Lys-NH2 (opioid receptor antagonist) and Ac-Arg-Tyr-Tyr-Arg-Trp-Lys-NH2 (highly potent and selective NOP-receptor agonist) was substituted by the (S)-2-(1-methyl-1H-indol-3-yl)propionic residue or the (S)-2-(5-methoxy-1H-indol-3-yl)propionic residue. The analgesic effect of the four newly synthesized compounds has been evaluated in male Wistar rats by PP- and HP tests and compared to the native templates. Further estimation of the mechanisms of action of each compound was achieved using specific antagonists-naloxone for opioid and JTC801 for the NOP receptor. Replacement of Trp with ß(2)-tryptophan analogues in 4th position (Ac-Arg-Phe-Met-Trp-Met-Lys-NH2) led to increased and longer lasting analgesic effect. The results obtained permit us to assume that both opioid and NOP receptors take part in the newly synthesized compounds analgesic effects.