Adipocytes as a new source of catecholamine production

Abstract

a b s t r a c tCatecholamines are an important regulator of lipolysis in adipose tissue. Here we show that rat adipocytes, isolated from mesenteric adipose tissue, express genes of catecholamine biosynthetic enzymes and produce catecholamines de novo. Administration of tyrosine hydroxylase inhibitor, alpha-methyl-p-tyrosine, in vitro significantly reduced concentration of catecholamines in isolated adipocytes. We hypothesize that the sympathetic innervation of adipose tissues is not the only source of catecholamines, since adipocytes also have the capacity to produce both norepinephrine and epinephrine.

Continuous cold exposure induces an anti-inflammatory response in mesenteric adipose tissue associated with catecholamine production and thermogenin expression in rats

“…NE that is produced mostly by the sympathetic nerves remained unchanged probably due to the quick physiological mechanisms of NE supplies maintenance consisting of NE turnover regulation. Due to a very high concentration of sympathetic NE stores within the mWAT compared to NE produced by adipose tissue cells such as macrophages or adipocytes (Vargovic et al 2011), it is probably impossible to distinguish the changes in non-sympathetic NE unless the mWAT is separated into the cell fractions (Vargovic et al 2011). However, in our previous study we have described cold-induced elevations of NE and EPI levels in adipocytes and stromal/vascular fractions, obtained from the mWAT by collagenase digestion (Kvetnansky et al 2012).…”

“…TH, which is the fi rst and rate-limiting enzyme involved in catecholamine biosynthesis, showed increased protein level in response to 1 day (p<0.05) or 7 days (p<0.01) cold exposure. In order to assess de novo synthesis of CAs in the mWAT, we analyzed TH and PNMT gene expression, which may refl ect non-sympathetic sources of CA production in macrophages and adipocytes, as it has been described previously (Nguyen et al 2011;Vargovic et al 2011;Vargovic et al 2013). Real time RT-PCR analysis revealed that 7 days cold induced a rise of TH (p<0.01) and PNMT (p<0.05) expression.…”

“…Catecholamines were analyzed in the mWAT samples, which were homogenized in 0.01 M HCl. Homogenates supernatants were used for the catecholamine measurements using 2-CAT ELISA kits (Labor Diagnostica Nord, Nordhorn, Germany) as described previously (Vargovic et al 2011). Th e values were normalized to proteins in homogenate, determined by bicinchoninic acid (BCA) Protein Assay (Th ermo Scientifi c, Rockford, IL).…”

“…Total RNA from the mWAT samples was isolated by TRI Reagent (MRC Ltd., Cincinnati, OH, USA), as described previously (Vargovic et al 2011). Reverse transcrip-tion and real time PCR were also performed, as described previously (Vargovic et al 2013).…”

“…We have identifi ed CA biosynthetic enzymes expression in the brown and white adipose tissues and described the stimulation of CA production in the cell fractions of the mesenteric adipose tissue in response to immobilization or cold stress (Vargovic et al 2011;Kvetnansky et al 2012;Vargovic et al 2013;Vargovic et al 2016). Since only the mWAT showed stress-inducible cell-specifi c CA production, from all the investigated adipose tissues (brown, epididymal, retroperitoneal, subcutaneous), we suppose that the mWAT may represent another active site of the beige adipogenesis, similarly as it has been described in the case of the scWAT.…”