Volume 2, Issue 3

Fetal cardiomyocytes have been utilized in studies on myocardial repair in the damaged hearts of rodents and other species. Changes in angiotensin II (Ang II) receptor expression, especially decline of its type II receptor (AT2), are known to occur during the growth of cardiomyocytes from fetus to adult. However, the extent to which changes in the signaling pathways of Ang II type I (AT1) and AT2 receptors via p42/44 mitogen-activated protein kinase (ERK1/2) activation affect the physiological and pathophysiological functions in cardiomyocytes has not been defined. The roles of these receptors were analyzed by confocal fluorescence microscopy, immunoblot analysis, reverse transcription PCR, measurement of intracellular 3′,5′-cyclic AMP levels and siRNA technology in cultured rat fetal cardiomyocytes. These studies revealed that Gq is required for Ang II-induced ERK1/2 activation via the synergy of AT1 and AT2 receptors. It has also been shown that phospholipase Cβ1, protein kinase Cα and protein kinase A mediate the feedback inhibition of ERK1/2 activation via c-Raf and/or other intermediate signaling molecules. The observed mechanism of Ang II-induced ERK1/2 activation in fetal cardiomyocytes could be relevant to the understanding of cardiomyocyte development and turnover, as well as clinical approaches using protein- and cell-based therapy for diseases such as heart failure.

Background: Both elevated and depressed testosterone (T) levels have been reported in Crohn's disease (CD). In this pilot study, effects of T administration on CD were assessed. Materials and methods: A total of 13 men with CD, aged 45–67 years, had subnormal plasma T (mean±SD=9.0±1.4 nmol/L) (reference >12.0); they were compared to a group of 110 men of similar age with sexual and urological problems whose plasma T was also subnormal: 10.4±1.4 nmol/L (p=0.02). All received treatment with parenteral T undecanoate for 24 months. The Crohn's Disease Activity Index (CDAI) was assessed as an indicator of the severity of the disease every 3 months. Levels of T and C-reactive protein (CRP) were compared between the 13 men with CD and the other men in this study. Values of CDAI and CRP were followed-up. Results: CRP levels were 22.7 mg/dL (95% confidence interval of the mean: 14.9–34.3) in the 13 men with CD vs. 3.5 (2.9–4.1) in 107 control men (p=0.001). Upon normalization of serum T, there was a significant decline of CDAI (from 243±19 to 89±9), CRP levels from 22.7±8.1 to 6.9±2.9 mg/dL, and white blood cell count. Hemoglobin/hematocrit increased significantly. Conclusions: Upon normalization of plasma T the CDAI and CRP levels decreased in hypogonadal patients with CD. The mechanism of this improvement could be through immunosuppressive effects of T, reducing chronic inflammation of the intestinal wall in CD.

5α-Reductases are crucial enzymes involved in the biosynthesis of dihydrotestosterone, the most potent natural androgen. To date, three types of 5α-reductases, chronologically named types 1, 2 and 3 5α-reductases (SRD5a-1, 2 and 3) have been described. In the present paper, we characterized the activity and compared the mRNA expression levels of SRD5a-3 with those of SRD5a-1 and 2 in various human tissues, and determined its sensitivity to finasteride and dutasteride. We have established HEK-293 cell line that stably expressed SRD5a-3 for studying its activity and the inhibitory effect of finasteride, using [ 14 C]labeled steroids. mRNA expression levels were quantified using real-time PCR in many male and female human tissues including the prostate, adipose tissue, mammary gland, as well as breast and prostate cancer cell lines. Incubation of HEK-SRD5a-3 cells with [ 14 C]4-androstenedione and [ 14 C]testosterone allowed us to show that SRD5a-3 can catalyze very efficiently both substrates 4-androstenedione and testosterone into 5α-androstanedione and dihydrotestosterone, respectively. We observed that the affinity of the enzyme for 4-androstenedione is higher than for testosterone. The activity of SRD5a-3 and SRD5a-2 are similarly sensitive to finasteride, whereas dutasteride is a much more potent inhibitor of SRD5a-3 than SRD5a-2. Tissue distribution analysis shows that SRD5a-3 mRNA expression levels are higher than those of SRD5a-1 and SRD5a-2 in 20 analyzed tissues. In particular, it is highly expressed in the skin, brain, mammary gland and breast cancer cell lines, thus suggesting that SRD5a-3 could play an important role in the production of androgens in these and other peripheral tissues.

Objective : To compare mean serum total testosterone, bioavailable-testosterone, and dihydrotestosterone levels between transdermal testosterone and oral testosterone undecanoate treatment. Methods : Multicentre, randomized, cross-over study; 44 men >18 years, testosterone ≤2.5 ng/mL. Two patches (Testopatch ® ) every other day in the morning or two capsules Pantestone ® 40 mg bid in each 22-day period. Hormone serum levels of four blood samples over the first and last 48 h of each treatment period. Results : Mean age 49 years. Mean testosterone before inclusion 1.99 ng/mL. Mean testosterone serum levels over the last 48 h of Testopatch treatment were superior to Pantestone (4.64 vs. 2.58 ng/mL, p<0.001). Testosterone trough levels at the end of each treatment period were significantly higher for Testopatch (3.15 vs. 2.45 ng/mL, p<0.01). Bioavailable-testosterone levels over the first and last 48 h of treatment were significantly greater with Testopatch than with Pantestone (p=0.001 and p<0.01). Dihydrotestosterone levels over the first and last 48 h of treatment (0.71 vs. 1.05 ng/mL and 0.68 vs. 0.89 ng/mL) as well as at trough (0.59 vs. 0.96 ng/mL) were significantly lower with Testopatch than with Pantestone (p<0.001, p<0.05, and p<0.001). SHBG levels decreased by Pantestone but not by Testopatch (p<0.001). Conclusions : Testopatch was superior to Pantestone to increase testosterone and bioavailable-testosterone levels in hypogonadal men from the first days and throughout the three weeks of treatment. Pantestone increased dihydrotestosterone to a larger extent and decreased SHBG.

17β-Hydroxysteroid dehydrogenases (17β-HSDs) are enzymes issued from convergent evolution of activity from various ancestral genes having different functions. Type 12 17β-HSD (17β-HSD12) was described as a bifunctional enzyme, involved in the biosynthesis of estradiol (E2) and the elongation of very long chain fatty acid (VLCFA). It catalyzes selectively the transformation of estrone (E1) into estradiol (E2) in human and primates, whereas in the mouse and Caenorhabditis elegans the enzyme catalyzes the 17β-reduction of both androgens and estrogens. It is also able to catalyze the reduction of 3-keto-acylCoA into 3-hydroxy-acylCoA in the elongation cycle of VLCFA biosynthesis. To further understand the physiological role of 17β-HSD12, we performed targeted disruption of the Hsd17b12 gene by substituting exons 8 and 9 that contain the active site with a neomycin cassette. The data indicate that heterozygous (HSD17B12 +/– ) mice are viable with reduced levels of sex steroids, whereas homozygous (HSD17B12 –/– ) mice show embryonic lethality. The present data are in agreement with the bifunctional activities of 17β-HSD12 suggesting that the VLCFA elongation activity, having its origin in the yeast, is most probably responsible for embryonic lethality in HSD17B12 –/– , whereas the more recently acquired 17β-HSD12 activity is responsible for reduced sex steroid levels in HSD17B12 +/– .