N-Methyl-5-tert-butyltryptamine: A novel, highly potent 5-HT1D receptor agonist.

It has been observed that reported 5-HT1D receptor agonists have at least one heteroatom (N, O, or S) on the 5-substituent of the indole. This has led to the hypothesis that a 5-substituent capable of participating in hydrogen bonding is critical for conveying high affinity. This article describes the synthesis and biological evaluation of a new series of 5-alkyltryptamine analogues, which does not have a heteroatom in the 5-substituent group. In contrast to the hypothesis, 5-alkyltryptamines all exhibit high binding affinities for the human 5-HT1D receptor. The size of the lipophilic alkyl group at the 5-position of the indole has significant impact on the 5-HT1D binding affinity. Compounds with a tert-butyl group at the 5-position such as 9d, 10, and 11 were identified. These analogues display high binding affinity (Ki < 1 nM) and moderate receptor selectivity in comparison with known antimigraine agents such as sumatriptan, naratriptan, rizatriptan, and VML-251.

Culture of marmoset blastocysts on matrigel: a model of differentiation during the implantation period.

BACKGROUND: The objective was to develop an experimental model for studying the differentiation of trophoblast and inner cell mass (ICM) during the early stages of implantation in primates. METHODS: Marmoset monkey blastocytes were used in these studies. Ovulation was timed by plasma progesterone assays in ovarian cycles initiated by administering a luteolytic agent to mating marmosets. Embryos were recovered from the uterus usually at the eight-cell stage and cultured in minimum essential medium containing fetal calf serum, insulin, and transferrin. The embryos that formed hatched blastocysts by about day 11 after ovulation were transferred for further development in Matrigel-coated culture chambers. After 2, 4, and 6 days of development, two blastocysts were processed at each interval and serially sectioned for light and electron microscopy. RESULTS: All blastocysts adhered to the Matrigel at their embryonic pole within 24 hours. Adherent polar cytotrophoblast was differentiating to syncytiotrophoblast at all time intervals, but syncytium was not detected in mural trophoblast until day 4 after attachment. By day 2 syncytial microvilli and processes had penetrated the Matrigel surface, whereas by days 4 and 6 cytotrophoblast that was differentiating to syncytiotrophoblast had invaded the matrix. Since all blastocysts maintained their structural integrity progressive differentiation of the ICM, endoderm and presumptive mesoderm was observed. A small amniotic cavity was observed at 2 days and by 6 days a distinct cavity separated polarized epiblast and amnion cells. Visceral and parietal endoderm were present at 2 days, and a completed primary yolk sac was observed by 4 days after attachment. In all blastocysts a basal lamina lined the inner surface of mural and polar trophoblast and the basal surface of the differentiating ICM. CONCLUSIONS: The developmental time sequence of the cultured blastocysts closely resembled the time frame reported for marmoset embryos implanting in utero. An effective model for studying trophoblast invasion and differentiation of embryonic germ cell layers has been established.

Sodium requirement for capacitation and membrane fusion during the guinea-pig sperm acrosome reaction.

Guinea-pig spermatozoa, incubated in a minimal culture medium (MCM-PL) containing 150 mM-Na+ and no added K+, capacitate within 2 h and respond to added Ca2+ with maximal percentage of acrosome reactions. When spermatozoa, initially capacitated in Medium MCM-PL, were washed and resuspended in saline-based media, the motile spermatozoa showed acrosome reactions only in response to added Ca2+ at an extracellular pH greater than 7.4. In contrast, resuspension of capacitated spermatozoa into isotonic sucrose or choline-based media containing no added Na+ and K+ (pH 7.8) did not support acrosome reactions in response to the addition of Ca2+. Examination under the electron microscope showed that these spermatozoa responded to added Ca2+ with swelling or cavitation of the acrosomal matrix but fusion of the plasma membrane and acrosomal membrane did not occur. Treatment of spermatozoa with monensin, a monovalent cationic ionophore, induced rapid acrosome reactions in the presence of extracellular Ca2+ and Na+. In contrast, spermatozoa incubated for 3 h in a sucrose-based Na+-deficient medium or Medium MCM-PL containing 10 mM-KCl failed to give a significant percentage of acrosome reactions in response to the addition of Ca2+, but the addition of ouabain (0.1 mM) prevented the K+ inhibition. Amiloride, a sodium channel blocker in various other tissues, retarded the development of acrosome reactions of spermatozoa incubated in Medium MCM-PL. Based on these data, it appears that an increase in intracellular Na+ has a functional role in acquisition of guinea-pig sperm fertilizing ability.