Based on the available literature, it can be assumed that in cases of post‐infarct heart failure (HF) and obesity, a significant change in the central regulation of the cardiovascular system takes place with, among others, the involvement of the apelinergic system. The main objective of the present study was to clarify the role of apelin‐13 in the central regulation of the cardiovascular system in Sprague Dawley rats with HF or sham operated (SO) and fed on a normal fat (NFD) or a high fat diet (HFD). The study was divided into two parts: Part I, hemodynamic studies; and Part II, biochemical and molecular studies. The animals were subjected to the following research procedures. Part I and II: feeding NFD or HFD; experimental induction of HF or SO; Part I: intracerebroventricular (ICV) infusion of the examined substances, monitoring of mean arterial blood pressure (MABP) and heart rate (HR); Part II: venous blood and tissue samples collected. ICV infusion of apelin‐13 caused significantly higher changes in ΔMABP in the SO NFD group. No changes were noted in ΔHR in any of the studied groups. Apelin and apelin receptor (APJ) mRNA expression in the brain and adipose tissues was higher in the HF rats. HFD causes significant increase in expression of apelin and APJ mRNA in the left ventricle. In conclusion, HF and HFD appear to play an important role in modifying the activity of the central apelinergic system and significant changes in mRNA expression of apelin and APJ receptor.