Regulation of Hepatic Gluconeogenesis by Nuclear Receptor Coactivator 6

Nuclear receptor coactivator 6 (NCOA6) is a transcriptional coactivator of nuclear receptors and other transcription factors. A general Ncoa6 knockout mouse was previously shown to be embryonic lethal, but we here generated liver-specific Ncoa6 knockout (Ncoa6 LKO) mice to investigate the metabolic function of NCOA6 in the liver. These Ncoa6 LKO mice exhibited similar blood glucose and insulin levels to wild type but showed improvements in glucose tolerance, insulin sensitivity, and pyruvate tolerance. The decrease in glucose production from pyruvate in these LKO mice was consistent with the abrogation of the fasting-stimulated induction of gluconeogenic genes, phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose-6-phosphatase (G6pc). The forskolin-stimulated inductions of Pck1 and G6pc were also dramatically reduced in primary hepatocytes isolated from Ncoa6 LKO mice, whereas the expression levels of other gluconeogenic gene regulators, including cAMP response element binding protein (Creb), forkhead box protein O1 and peroxisome proliferator-activated receptor γ coactivator 1α, were unaltered in the LKO mouse livers. CREB phosphorylation via fasting or forskolin stimulation was normal in the livers and primary hepatocytes of the LKO mice. Notably, it was observed that CREB interacts with NCOA6. The transcriptional activity of CREB was found to be enhanced by NCOA6 in the context of Pck1 and G6pc promoters. NCOA6-dependent augmentation was abolished in cAMP response element (CRE) mutant promoters of the Pck1 and G6pc genes. Our present results suggest that NCOA6 regulates hepatic gluconeogenesis by modulating glucagon/cAMP-dependent gluconeogenic gene transcription through an interaction with CREB.

Evaluation of androgens in the scalp hair and plasma of patients with male-pattern baldness before and after finasteride administration

BACKGROUND

Finasteride, a competitive inhibitor of the enzyme 5alpha-reductase II, is widely used as a medical treatment for patients with male-pattern baldness (MPB), which is affected by the distribution of androgenic steroids. It is also notable that the androgenic effect in MPB is different for each region of the head.

OBJECTIVES

To study the effect of the drug finasteride, we quantified androgenic steroids in the vertex and occipital scalp hair and in the plasma of patients with MPB.

METHODS

The patients with MPB, aged 23-52 years, were treated with finasteride 1 mg daily for 5 months. The hair and plasma samples were hydrolysed, extracted with n-pentane, and derivatized with MSTFA:NH4I:DTE (1000:4:5, v/w/w). We analysed the concentrations of dihydrotestosterone (DHT) and testosterone (T) in the hair and plasma using gas chromatography-mass spectrometry (GC-MS).

RESULTS

In the hair, the ratio of DHT/T was decreased in the vertex scalp hair after the individual received finasteride (P < 0.005). However, we found no significant difference in the ratio of DHT/T in the occipital scalp hair before and after individuals received finasteride. Like the results in the vertex scalp hair, the ratio of DHT/T in the plasma was remarkably decreased after finasteride administration (P < 0.001).

CONCLUSIONS

This study supports the effect of finasteride in patients with MPB by examining the decreased level of DHT/T in scalp hair and in plasma. Thus, in view of the androgenic effect in the different hair regions, the vertex scalp hair plays a more important role for patients with MPB treated with finasteride than does the occipital hair.