The thermogenic actions of natriuretic peptide in brown adipocytes: The direct measurement of the intracellular temperature using a fluorescent thermoprobe

Abstract

In addition to the various effects of natriuretic peptides (NPs) on cardiovascular systems, increasing attention is being paid to the possibility that NPs induce adipose tissue browning and activate thermogenic program. We herein established a direct intracellular temperature measurement system using a fluorescent thermoprobe and investigated the thermogenic effects of A-type NP (ANP) on brown adipocytes. The thermoprobe was successfully introduced into rat brown adipocytes, and the temperature dependent change in fluorescence intensity ratio was measured using a fluorescence microscope. After one-hour incubation with ANP, the degree of the change in fluorescence intensity ratio was significantly higher in ANP-treated (P < 0.01) adipocytes compared to untreated controls. The ANP treatment increased uncoupling protein-1 (UCP1) mRNA levels, which is one of the markers of thermogenesis in adipocytes, while the intracellular ATP content was not changed, indicating mitochondrial uncoupled respiration. Intriguingly, these thermogenic actions of ANP were more prominent when brown adipocytes were incubated at 35 °C than at 37 °C. Moreover, the increase in the intracellular temperature and the expression of UCP1 induced by ANP were cancelled by p38MAPK inhibition. Taken together, this study directly demonstrated the thermogenic actions of ANP in brown adipocytes through the use of a novel method of intracellular temperature measurement.

Therapeutic hypothermia after cardiac arrest increases the plasma level of B-type natriuretic peptide

“…Recent evidence indicates that NP/cGMP-dependent protein kinase cascades also regulate the energy balance and glucose homeostasis 12 . We also demonstrated the thermogenic actions of NP in rat brown adipocytes through the p38 mitogen-activated protein kinase (MAPK)-uncoupling protein 1 (UCP1) pathway by increasing the intracellular temperature 13 . These findings suggested that NPs have a novel self-protective function when the core body temperature or the local tissue (including the heart itself) temperature decreases to a level that results in severe hemodynamic conditions, such as serious heart failure.…”

Induction of Adipose Tissue Browning as a Strategy to Combat Obesity

“…However, identification of NP receptors (NPRs) expression in adipose tissue shed new light on ANP/BNP pathways’ role in the whole-body homeostasis. Subsequently, ANP was found to induce lipolysis in white adipocytes and thermogenesis in BAT, while both NPs, via the cGMP-PKG-mTORC1 pathway, can increase UCP1 expression and mitochondrial content in adipocytes leasing to WAT browning [ 41 , 42 , 43 ]. Accordingly, mice with npra knockout suffer from cardiac hypertrophy and have significantly higher adipose tissue content than wild-type animals [ 41 ].…”

Cardiac ischemia–reperfusion injury under insulin-resistant conditions: SGLT1 but not SGLT2 plays a compensatory protective role in diet-induced obesity

“…Immunoblotting was performed as previously described [7,[26][27][28] with rabbit polyclonal anti-SGLT1 (1:200, #H-85; Santa Cruz Biotechnology, CA, USA), anti-GLUT4 (1:1000, #ab33780; Abcam, Cambridge, MA, USA), anti-GLUT1 (1:1000, #12939; Cell Signaling Technology, Tokyo, Japan), or mouse monoclonal anti-α1 Na-K-ATPase (1:1000, #ab7671; Abcam). The signals were detected using chemiluminescence.…”

“…Total RNA was extracted from the frozen tissues using TRIzol reagent (Invitrogen) and a quantitative real-time PCR was performed using a StepOnePlus Real-time PCR System and the StepOne Software program (Applied Biosystems), as described previously [28]. The real-time PCR protocol consisted of one cycle at 95 °C for 20 s followed by 40 cycles at °C for 1 s and 60 °C for 20 s using the primers for Slc5a2 (Mm00453831_m1; Applied Biosystems) and GAPDH (Mn03302249_g1; Applied Biosystems).…”