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of ethyl (imidazolidine-2-ylidene)acetate with aromatic esters bearing labile halogen in ortho-position leads to fused heterocycles, which is formed by substitution of halogen atom with α-carbon atom of cyclic ketene aminal and binding of nitrogen atom with carbonyl carbon atom of aromatic ester. [ABSTRACT FROM AUTHOR]

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG), due to binding to the LH/hCG receptor, activate the adenylyl cyclase (AC) system which regulates testosterone (T) production. Long-term administration of LH and hCG causes desensitization of this system and attenuates the steroidogenic response, thereby necessitating the search for new agonists of the LH/hCG receptor. The aim of the work was to explore, in comparison with hCG, the stimulatory effects of the previously developed thieno[2,3-d]pyrimidines, TP03 and TP04, and a new thieno[2,3-d]pyrimidine derivative, 5-amino-N-(tert-butyl)-4-(3-(4-aminopyrimidine-5-carboxamido)-phenyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxamide (TP37), on AC activity in rat testicular membranes, as well as on T production and gene expression of the LH/hCG receptor and the key testicular steroidogenic proteins under conditions of a single and 3-day administration to male rats. hCG increased AC activity in testicular membranes more efficiently compared to thieno[2,3-d]pyrimidines, and after a single injection (50 and 100 IU/rat) was superior to TP03 and TP04 (15–50 mg/kg) in its steroidogenic effect. After a 3-day administration, the steroidogenic effect of hCG was attenuated compared to that for TP03 and TP04. After 3 days of treatment with gonadotropin, testicular expression of genes encoding the StAR protein and cytochrome P450scc was considerably increased, but expression of the Lhr and Cyp17a1 genes encoding LH/hCG receptor and cytochrome P450-17α was suppressed. TP03 and TP04 slightly increased StAR gene expression but did not affect expression of other genes. TP37, which was active in vitro, after a short stimulation of T production, suppressed the steroidogenic function at a dose of 50 mg/kg, probably due to its degradation and the ability to suppress Cyp17a1 gene expression. Our data indicate significant differences in the mechanisms underlying the effect of gonadotropins and thieno[2,3-d]pyrimidines with an activity of LH/hCG receptor agonists on testicular steroidogenesis. We also demonstrate that long-term administration of thieno[2,3-d]pyrimidines to stimulate T production does not attenuate steroidogenesis and induces no LH resistance. [ABSTRACT FROM AUTHOR]

In clinical practice, luteinizing hormone (LH) and chorionic gonadotropin (CG) are used as activators of the LH receptor, leading to the stimulation of gonadal steroidogenesis. However, high doses of gonadotropin preparations cause a number of side effects. Here we demonstrate that the pretreatment of male rats with TP03, an allosteric agonist of the LH receptor, at doses of 7.5–25 mg/kg significantly increases the testosterone production-stimulating effect of CG administered at a dose of 50 IU/rat, which is twice as low as that inducing a maximum steroidogenic effect. We assume that this is due to additivity of the CG and TP03 effects, as well as the potentiating effect of TP03 on CG signaling pathways. Three hours after CG administration to TP03-pretreated rats, the activation pattern of the genes of steroidogenic enzymes and LH receptor exhibits specific changes which mainly concern 3p-dehydrogenase gene expression. The obtained data indicate a prospectivity of TP03 and CG co-application allowing the effective dose of gonadotropin preparations to be reduced. [ABSTRACT FROM AUTHOR]

The luteinizing hormone (LH) and human chorionic gonadotropin (hCG) stimulate the testosterone (T) production in Leydig cells via specifical binding to the LH/hCG receptor extracellular domain. The LH/hCG receptor can also be activated by low-molecular-weight (LMW) agonists that bind to the allosteric site located inside the transmembrane receptor channel. Since the allosteric sites in the LH/hCG and thyroid-stimulating hormone (TSH) receptors share a similar structure, LMW agonists of the LH/hCG receptor can affect activity of the TSH receptor and the synthesis of thyroid hormones which depend on this receptor. When designing selective activators of steroidogenesis, it is necessary to rule out this possibility. The aim of this study was to explore the effect of the seven previously synthesized thienopyrimidines (TPs), LMW agonists of the LH/hCG receptor, on the basal and hCG- and TSH-stimulated adenylyl cyclase (AC) activity in plasma membranes isolated from the rat testes and thyroid as well as on the basal and luliberin- and thyroliberin-stimulated levels of T and thyroid hormones following intraperitoneal (i.p.) TP administration to male rats. All seven TPs (10−4 M) increased the AC basal activity in rat testicular membranes, and in the case of combined action of TPs and hCG their stimulatory effects were additive. TPs did not affect the basal and TSH-stimulated AC activity in thyroid membranes. When administered to male rats, TPs (i.p., 25 mg/kg) increased the T level. The effect of TP03, a most active LH/hCG receptor LMW agonist, persisted under luliberin-induced activation of the gonadal axis. The nicotinamide moiety of TP21, in contrast to the structurally similar TP03, contains an additional methoxy group which alters receptor specificity of this compound. Thus, with the exception of TP21, all TPs sharing LH/hCG receptor agonistic activity, both under in vitro and in vivo conditions, do not affect the TSH receptor, indicative of their selectivity toward the gonadal axis. [ABSTRACT FROM AUTHOR]

Abstract—It was shown that the thienopyrimidine derivative TP03, a low-molecular-weight agonist of the luteinizing hormone receptor (LHR), during the treatment of male rats for 7 days steadily increased the production of testosterone (T), whose elevated level was retained for 7 days, and increased the expression of the gene for LHR, which indicates the maintenance of the sensitivity of Leydig cells to gonadotropins. At the same time, the steroidogenic effect of human chorionic gonadotropin (hCG), which significantly increased the T level on the first day of administration, was further weakened, which was accompanied by a decrease in the expression of the gene for LHR in the testes, indicating the development of resistance of Leydig cells to hCG. Along with this, in the case of hCG administration, a compensatory increase in the expression of genes of the steroidogenic enzymes, such as cytochrome P450scc and dehydrogenase 3β-HSD, was shown in the testes, while in the case of TP03 administration this effect was absent. [ABSTRACT FROM AUTHOR]

The article presents chemical reactions for cyclocondensation of ethyl (imidazolidine-2-ylidene)acetate with aromatic esters bearing labile halogen in ortho-position.

Human chorionic gonadotropin that is widely used for improving spermatogenesis. The effect of chorionic gonadotropin is mediated through luteinizing hormone receptor. Treatment with gonadotropin is associated with undesirable effects due to hyperactivation of testosterone production and luteinizing hormone receptor desensitization. A promising alternative could be low-molecular-weight agonists of luteinizing hormone receptors, but their effects on spermatogenesis have not been investigated. Here we analyzed the effect of a thieno[2,3-d]pyrimidines (TP), 4-((3-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno [2,3-d]pyrimidine-4-yl) phenyl)carbamoyl)pyridine 1-oxide (TP22), an allosteric agonist of luteinizing hormone receptors, on the seminiferous tubules and spermatogenic cells in 4- and 18-month-old male rats and in animals with diabetes mellitus. TP22 and gonadotropin were administered in daily doses of 15 mg/kg and 20 U/rat for 5 days. Blood testosterone level, morphology of the seminiferous tubules, and the number of germ cells in them were estimated. Being comparable by the efficiency to gonadotropin, TP22 increased the testosterone level in all the studied groups of rats and restored epithelium thickness in the seminiferous tubules and the number of spermatogonia and pachytenic spermatocytes that are reduced in aging and diabetes, but, unlike gonadotropin, did not suppress the expression of luteinizing hormone receptor. The efficacy of TP22 as a stimulator of testicular spermatogenesis has been demonstrated both under normal conditions and in age-related and diabetes-associated reproductive dysfunctions. [ABSTRACT FROM AUTHOR]