Improved risk-benefit ratio for topical triamcinolone acetonide in Transfersome in comparison with equipotent cream and ointment: a randomized controlled trial.

BACKGROUND: Transfersome is a drug delivery technology based on highly deformable, ultraflexible lipid vesicles which penetrate the skin when applied non-occlusively. OBJECTIVES: To assess the advantages of this carrier-based formulation in humans, the efficacy and the atrophogenic potential of triamcinolone acetonide (TAC) in Transfersome was compared with commercially available TAC-containing cream and ointment. METHODS: Healthy volunteers were enrolled in double-blind, placebo-controlled clinical trials with random study medication assignment to the test areas. RESULTS: A 10-fold lower dose of TAC in Transfersome(R) (2.5 micro g cm-2) was bioequivalent to 25 micro g cm-2 TAC in conventional formulations as measured by erythema suppression (cream: P = 0.01, ointment: P < 0.001). A skin blanching assay revealed different kinetics of the formulations, with a delayed onset of action of the Transfersome and ointment preparations. Ultrasonic measurements revealed a significantly reduced atrophogenic potential. There was a 12.1% reduction in skin thickness given by TAC in Transfersome compared with a 21.1% reduction given by a bioequivalent dose in TAC cream after a 6-week treatment period (P = 0.007). CONCLUSIONS: Transfersome may significantly improve the risk-benefit ratio of topically applied glucocorticosteroids.

Ontogeny of the GNRH-, glutaminase- and glutamate decarboxylase-gene expression in the hypothalamus of female rats.

Amino acid neurotransmitters like gamma-aminobutyric acid (GABA) and glutamate (GLU) are involved in the regulation of hypothalamic gonadotropin releasing hormone (GnRH) release. We investigated, whether there are changes of gene expression in the rat hypothalamus for GnRH, GnRH receptor, as well as glutaminase and glutamate decarboxylase, two enzymes regulating neurotransmitter concentrations of GLU and GABA in the brain during the ontogeny. After reverse transcription-polymerase chain reaction (RT-PCR) we used an ELISA method to quantify PCR products. In 15-day old animals high plasma luteinizing hormone (LH) levels with pronounced variations were found. In 25-day old animals LH values were low, whereas in 35-day old rats LH levels increased significantly indicating the reactivation of the GnRH-pulse generator at the beginning of puberty. In parallel to these changes, the mRNA levels of the GnRH receptor in the mediobasal hypothalamus were high at day 15, significantly lower at day 25 and again high at day 35 after birth (ELISA O.D. GnRH-R day 15: 0.46+/-0.07, day 25: 0.16+/-0.04, day 35: 0.36+/-0.04; p<0.01), but no changes of GnRH receptor gene expression were found in the preoptic area. The mRNA of GnRH in the preoptic area as well as mRNA levels of glutaminase and glutamate decarboxylase in the mediobasal hypothalamus and the preoptic area did not change during ontogeny. We conclude that hypothalamic GnRH receptors are involved in the characteristic changes of LH secretion patterns during sexual maturation. Major changes of GnRH receptor gene expression occurred in the mediobasal hypothalamus and correlated well with plasma LH levels, whereas hypothalamic mRNA levels of GnRH, glutaminase and glutamate decarboxylase did not change within the different age groups. Thus the activity of the GABA- and glutamatergic system during ontogeny may be regulated at the receptor or postreceptor level.

Regulation of steroid production and its function within the corpus luteum.

During the second half of the luteal phase, the human corpus luteum becomes responsive to regular luteinizing hormone (LH) pulses. These LH pulses stimulate progesterone secretion tonically, and during this tonic stimulation, additional LH-independent progesterone pulses occur, which are particularly pronounced in women with human chorionic gonadotropin-stimulated luteal function. No progesterone pulses are seen in women suffering from corpus luteum deficiency due to absent LH pulses. The corpus luteum thus has a progesterone pulse generator turned on by gonadotropins but functioning for several hours without further gonadotropic support. This pulse generator appears to be regulated by intraluteal auto-/paracrine mechanisms, which we have investigated in a porcine model using molecular, cellular, and in vivo tools. Luteal oxytocin and progesterone release occurs in tightly coupled pulses. In vivo, oxytocin and prostaglandin F2 alpha(PGF2 alpha) stimulate estradiol and progesterone release and estradiol itself further stimulates progesterone release. Analysis of the different luteal cell compartments (large luteal cells, small luteal cells, fibroblasts) suggests an intraluteal circuit that involves paracrine effects of estradiol, oxytocin, and PGF2 alpha. At the time of luteolysis, the luteotropic effects of estradiol are inhibited by tumor necrosis factor derived from invading macrophages and the intraluteal circuit is thereby disrupted, leading to luteolysis.

Immune-endocrine interactions affecting luteal function in pigs.

The formation, normal function and destruction of corpora lutea are essential features of normal reproduction. Although the formation of corpora lutea from follicles is largely dependent on pituitary gonadotrophins, the process of luteolysis is locally regulated and poorly understood. The corpus luteum consists of several steroidogenic and nonsteroidogenic cell types that interact with each other in a paracrine manner. Under cell culture conditions, large luteal cells that stem from follicular granulosa cells can be identified easily under the microscope and collected individually for single cell RT-PCR. As each of the 120 large luteal cells express the gene encoding 3 beta-hydroxysteroid dehydrogenase, it appears that all large luteal cells are steroidogenic. Large luteal cells also express the oestrogen receptor gene and as they are known to produce oestradiol, it can be concluded that the steroid acts in an auto- or intracrine manner in large luteal cells. Since we showed previously that oestradiol stimulates progesterone release under in vitro and in vivo conditions, it can be concluded that the steroid is an important intraluteally acting luteotrophic signal. At the time of luteal regression, macrophages invade the corpora lutea and their cytokine products, particularly tumour necrosis factor alpha (TNF alpha), appear to be involved in reduced steroid secretion. Indeed, TNF alpha inhibits production of progesterone and oestradiol from cultivated luteal cells. In sows, oestradiol is a strong luteotrophic factor and the production of oestradiol and of its receptor is downregulated by TNF alpha. Thereby, TNF alpha not only exerts direct luteolytic effects but also prevents the luteotrophic effects of oestradiol. Hence, it has an anti-luteotrophic action. In most species, functional luteolysis is accompanied by morphological regression of the corpus luteum. This structural luteolysis also appears to involve TNF alpha, as we have shown in pigs that expression of TNF alpha gene is high during luteolysis. Furthermore, TNF alpha stimulates programmed cell death (apoptosis) in luteal cells kept under culture conditions.