Effects of endokinin A/B, endokinin C/D, and endomorphin-1 on the regulation of mean arterial blood pressure in rats

[PI3K/Akt signaling pathway mediates the protective effect of endomorphin-1 postconditioning against myocardial ischemia-reperfusion injury in rats]

OBJECTIVE

To investigate the role of PI3K/Akt signaling pathway in mediating the protective effect of endomorphin-1 against myocardial ischemia-reperfusion (IR) injury.

OBJECTIVE

Fifty SD male rats were randomly divided into sham operation group, myocardial IR group, endomorphin-1 post-treatment group (EM50 group), endomorphin-1+wortmannin (a PI3K/Akt signaling pathway inhibitor) treatment group (EM50+Wort group), and wortmannin treatment group (Wort group). Rat models of myocardial IR injury were established by ligation of the left anterior descending coronary artery for 30 min followed by reperfusion for 120 min. The heart rate and mean arterial pressure were monitored during the experiment. Plasma levels of LDH, CK-MB, cTnI, IL-6, TNF-α, SOD and MDA were measured after reperfusion. The mRNA expression of Bax and Bcl-2 was detected using RT-PCR, and the expression of apoptosis-related protein cleaved caspase-3, phosphorylated Akt protein and total Akt protein in myocardial tissue was detected using Western blotting.

OBJECTIVE

Myocardial IR injury significantly decreased heart rate and blood pressure of the rats in comparison with the sham operation (P < 0.05). Compared with those in the IR group, the rats in EM50 group showed significantly increased heart rate and blood pressure (P < 0.05) with decreased plasma LDH, CK-MB, cTnI, IL-6, TNF-α and MDA levels (P < 0.05), increased SOD activity (P < 0.05), increased expression of p-Akt protein and Bcl-2 mRNA (P < 0.05), and decreased expression of Bax mRNA and cleaved caspase-3 protein (P < 0.05). In EM50+Wort group, the heart rate and blood pressure were significantly lowered (P < 0.05), plasma LDH, CK-MB, cTnI, IL-6, TNF-α and MDA levels increased (P < 0.05), SOD activity decreased (P < 0.05), the expression of p-Akt protein and Bcl-2 mRNA was reduced (P < 0.05), and the expression of Bax mRNA and cleaved caspase-3 protein increased (P < 0.05) as compared with those in EM50 group.

OBJECTIVE

EM-1 postconditioning can regulate cardiac myocyte apoptosis and reduce myocardial IR injury in rats. The PI3K/Akt signaling pathway may play a role in mediating the myocardial protective effects of EM-1 postconditioning.

Role of hemokinin-1 in health and disease

Hemokinin-1 (HK-1), the newest tachykinin encoded by the Tac4 gene was discovered in 2000. Its name differs from that of the other members of this peptide family due to its first demonstration in B lymphocytes. Since tachykinins are classically found in the nervous system, the significant expression of HK-1 in blood cells is a unique feature of this peptide. Due to its widespread distribution in the whole body, HK-1 is involved in different physiological and pathophysiological functions involving pain inflammation modulation, immune regulation, respiratory and endocrine functions, as well as tumor genesis. Furthermore, despite the great structural and immunological similarities to substance P (SP), the functions of HK-1 are often different or the opposite. They both have the highest affinity to the tachykinin NK1 receptor, but HK-1 is likely to have a distinct binding site and signalling pathways. Moreover, several actions of HK-1 different from SP have been suggested to be mediated via a presently not identified own receptor/target molecule. Therefore, it is very important to explore its effects at different levels and compare its characteristics with SP to get a deeper insight in the different cellular mechanisms. Since HK-1 has recently been in the focus of intensive research, in the present review we summarize the few clinical data and experimental results regarding HK-1 expression and function in different model systems obtained throughout the 16years of its history. Synthesizing these findings help to understand the complexity of HK-1 actions and determine its biomarker values and/or drug development potentials.

Endogenous opiates and behavior: 2011

This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

Effects of endokinin A/B and endokinin C/D on the antinociception properties of hemopressin in mice

The current study evaluated the effects of hemopressin (HP) on pain modulation by endokinin A/B (EKA/B) and endokinin C/D (EKC/D) at the supraspinal level in mice. Intracerebroventricular administration of HP (10 nmol) fully antagonized the hyperalgesia induced by EKA/B (10, 30, and 100 pmol), and induced a dose-dependent potent analgesic effect. HP at different concentrations (10 pmol, 100 pmol, and 1 nmol) showed varying effects on the analgesic effect of EKA/B (3 nmol). HP extended the duration of the analgesic effect of EKC/D (3 nmol). Moreover, HP at different concentrations (10 pmol, 5 pmol, 1 pmol, and 100 fmol) co-administered with EKC/D (30 pmol) induced significant analgesia at two different time points: 5 min and 50 min. To investigate the antinociceptive mechanism, we used SR140333B and SR142801. HP (1 pmol) potentiated the analgesic effect of SR140333B (100 pmol)+EKA/B (30 pmol) in 5-10 min, while HP (100 pmol) had no effect in the analgesia induced by SR140333B (3 nmol)+EKA/B (3 nmol). HP (1 nmol) fully inhibited the analgesic effect of SR140333B (3 nmol)+EKC/D (3 nmol) or SR142801 (3 nmol)+EKC/D (3 nmol). HP (1 pmol) weakened the analgesic effect of SR142801 (100 pmol)+EKA/B (30 pmol), but HP (100pmol) strengthened the analgesic effect of SR142801 (3 nmol)+EKA/B (3 nmol). These findings may pave the way for a new strategy on investigating the interaction between tachykinins and opioids on pain modulation.