CB2: a cannabinoid receptor with an identity crisis

Design of amino acid- and carbohydrate-based anticancer drugs to inhibit polymerase η

DNA polymerase η (polη) is of significant value for designing new families of anticancer drugs. This protein takes a role in many stages of the cell cycle, including DNA replication, translesion DNA synthesis, and the repairing process of DNA. According to many studies, a high level of expression of polη in most cases has been associated with low rates of patients' survival, regardless of considering the stage of tumor cells. Thus, the design of new drugs with fewer side effects to inhibit polη in cancerous cells has attracted attention in recent years. This project aims to design and explore the alternative inhibitors for polη, which are based on carbohydrates and amino acids. In terms of physicochemical properties, they are similar to the traditional anticancer drugs such as Cytarabine (cytosine arabinose). These alternative inhibitors are supposed to disrupt the DNA replication process in cancerous cells and prevent the tumor cells from mitosis. These newly designed structures, which are based on natural products, are expected to be non-toxic and to have the same chemotherapeutic impact as the traditional agents. The combinatorial use of quantum mechanics studies and molecular dynamic simulation has enabled us to precisely predict the inhibition mechanism of the newly designed structure, which is based on carbohydrates and amino acids, and compare it with that of the traditional chemotherapeutic drugs such as Cytarabine. Our results suggest that the inhibitors containing the natural building blocks of amino acid and carbohydrate could be considered alternative drugs for Cytarabine to block polη.

A Selective Histamine H4 Receptor Antagonist, JNJ7777120, Is Protective in a Rat Model of Transient Cerebral Ischemia

Cerebral ischemia is a multifactorial pathology characterized by different events evolving in time. The acute injury, characterized by excitoxicity, is followed by a secondary brain injury that develops from hours to days after ischemia. Extracellular levels of histamine increase in the ischemic area after focal cerebral ischemia induced by occlusion of the middle cerebral artery (MCAo). The histamine H4 receptor (H4R) is predominantly expressed in cell types of immune system where is involved in the regulation of immunological and inflammatory responses, and in numerous area of the Central Nervous System (CNS) including cortex and striatum. Our aim was to assess the putative neuroprotective effects of the potent and selective H4R antagonist, JNJ7777120 (JNJ), chronically administered (1 mg/kg, i.p., twice/day for 7 days) on damage parameters in a rat model of focal ischemia induced by transient MCAo (tMCAo). Chronic treatment with the H4R antagonist JNJ, significantly protected from the neurological deficit and from body weight loss after tMCAo. Seven days after the ischemic insult, JNJ reduced the volume of the ischemic cortical and striatal damage, the number of activated microglia and astrocytes in the ischemic cortex and striatum and decreased the plasma levels of IL-1β and TNF-α, while increased the levels of IL-10. Two days after ischemia, JNJ has reduced granulocyte infiltration in the ischemic area. Results demonstrate that the selective antagonist of H4R, JNJ, systemically and chronically administered after ischemia, reduces the ischemic brain damage, improves the neurological deficit and decreases blood pro-inflammatory cytokines, suggesting that H4R is a valuable pharmacological target after focal brain ischemia.

Cannabinoid receptor 2 and several digestive system diseases

The endocannabinoid system is made up of endocannabinoid, cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2). A multitude of physiological effects and putative pathophysiological roles have been proposed for the endogenous cannabinoid system in the gastrointestinal tract, liver, pancreas and tumors. This paper aims to review the endocannabinoid system and the relations of CB2 with irritable bowel syndrome, inflammatory bowel disease, pancreatitis, hepatic disease and digestive system tumors.

Central dopaminergic neurotransmission plays an important role in thermoregulation and performance during endurance exercise

Dopamine (DA) has been widely investigated for its potential role in determining exercise performance. It was originally thought that DA's ergogenic effect was by mediating psychological responses. Recently, some studies have also suggested that DA may regulate physiological responses, such as thermoregulation. Hyperthermia has been demonstrated as an important limiting factor during endurance exercise. DA is prominent in the thermoregulatory centre, and changes in DA concentration have been shown to affect core temperature regulation during exercise. Some studies have proposed that DA or DA/noradrenaline (NA) reuptake inhibitors can improve exercise performance, despite hyperthermia during exercise in the heat. DA/NA reuptake inhibitors also increase catecholamine release in the thermoregulatory centre. Intracerebroventricularly injected DA has been shown to improve exercise performance through inhibiting hyperthermia-induced fatigue, even at normal ambient temperatures. Further, caffeine has been reported to increase DA release in the thermoregulatory centre and improves endurance exercise performance despite increased core body temperature. Taken together, DA has been shown to have ergogenic effects and increase heat storage and hyperthermia tolerance. The mechanisms underlying these effects seem to involve limiting/overriding the inhibitory signals from the central nervous system that result in cessation of exercise due to hyperthermia.

Pharmacological role of efflux transporters: Clinical implications for medication use during breastfeeding

The World Health Organisation recommends exclusive breastfeeding for the first six months of an infant’s life and in combination with solid food thereafter. This recommendation was introduced based on research showing numerous health benefits of breastfeeding for both the mother and the infant. However, there is always concern regarding the transfer of medications from mother to their breastfed baby via milk. Pharmacokinetic properties of a drug are usually used to predict its transferability into breast milk. Although most drugs are compatible with breastfeeding, cases of toxic drug exposure have been reported. This is thought to be due to active transport mechanisms whereby efflux transporter proteins expressed in the epithelial cells of the mammary gland actively secrete drugs into milk. An example of such efflux transporters including the breast cancer resistance protein which is strongly induced during lactation and this could result in contamination of milk with the substrates of this transporter which may place the suckling infant at risk of toxicity. Furthermore, there is little known about the substrate specificity of most efflux transporters as we have highlighted in this review. There also exists some degree of contradiction between in vivo and in vitro studies which makes it difficult to conclusively predict outcomes and drug-drug interactions.