Original Research: Orexins A and B stimulate proliferation and differentiation of porcine preadipocytes

Abstract

Orexin A (OXA) and B (OXB) are neuropeptides which regulate appetite, energy expenditure, and arousal via G-protein coupled receptors termed as OXR1 and OXR2. The aim of this study was to characterize the effects of OXA and OXB on proliferation and differentiation of porcine preadipocytes. Porcine preadipocytes express both OXRs. OXA and OXB enhance porcine preadipocyte proliferation by 54.8% or 63.2 %, respectively. OXA and OXB potentiate differentiation of porcine preadipocytes, as judged by the increased lipid accumulation and expression of proadipogenic genes. Cellular lipid content after exposure of preadipocytes for six days to 100 nM OXA or OXB increased by 82.2% or 59.2%, respectively. OXA and OXB suppressed glycerol release by 23.9% or 24.9% in preadipocytes differentiated for six days. OXA (100 nM) increased peroxisome proliferator-activated receptor gamma (PPAR) expression in cells differentiated for 24 h by 100.5%. PPAR expression was also stimulated in preadipocytes differentiated in the presence of 10 nM (58.3%) or 100 nM OXA (50.6%) for three days. OXB potentiated PPAR mRNA expression at 1 nM (59%), 10 nM (53.2%), and 100 nM (73.9%) in cells differentiated for three days. OXA increased CCAAT/enhancer binding protein alpha expression in preadipocytes differentiated for six days by 65%. OXB stimulated CCAAT/enhancer binding protein beta expression in preadipocytes differentiated for three days at 10 nM (149.5%) as well as 100 nM (207.2%). Lipoprotein lipase mRNA expression increased in cells treated with 10 nM OXA by 152.6% and 100 nM OXA by 162%. Lipoprotein lipase expression increased by 134% at 100 nM OXB. Furthermore, OXA (100 nM) and OXB (100 nM) increased leptin mRNA expression in preadipocytes differentiated for three days by 49.9% or 71.3%, respectively. These data indicate that orexin receptors may be relevant in the context of white adipose tissue formation.

Hypocretin/orexin modulates body weight and the metabolism of glucose and insulin

“…It was also shown that the lipoprotein lipase content of adipocytes increased significantly after approximately one-week incubation with 100 nM of either orexin A or orexin B. 87 This observation points to the ability of the orexins to increase the enzyme that degrades fat.…”

“…88 Lipoprotein lipase content was also shown to increase after incubation of WAT with orexin. 87 All of these lead to increased lipolysis, lower fat deposition, and reduction in the fat content of the body.…”

“…Moreover, studies derived from intraventricular injection of Hcrts/orexins showed that orexin A and B receptors are stimulated leading to increased activity of the enzyme lipoprotein lipase and increased firing of the sympathetic nervous system . Lipoprotein lipase content was also shown to increase after incubation of WAT with orexin . All of these lead to increased lipolysis, lower fat deposition, and reduction in the fat content of the body.…”

Comparative analysis of meat sensory quality, antioxidant status, growth hormone and orexin between Anqingliubai and Yorkshire pigs

“…GH (a peptide hormone) promoted the muscle growth and correlated negatively with lipogenesis (Cordoba-Chacon et al 2015). However, orexin regulated food intake and correlated positively with lipid accumulation (Wojciechowicz et al 2016). Therefore, the serum GH and orexin concentrations could partly explain the different IMF content between pig breeds.…”

Orexin system is expressed in avian liver and regulates hepatic lipogenesis via ERK1/2 activation

“…In line with our results, previous studies have shown that orexin stimulated lipid accumulation in primary rat adipocytes and 3T3-L1 cells 23 . Pruszynska-Oszmalek and co-workers reported that orexin stimulated proliferation and differentiation of porcine preadipocytes and regulated lipid metabolism 29,48 . It is noteworthy to mention that, as for orexin system and for the same reasons mentioned above, mRNA and protein levels of lipogenic factors were not correlated.…”