Neuropeptide‐E‐1 Antagonizes the Action of Melanin‐Concentrating Hormone on Stress‐Induced Release of Adrenocorticotropin in the Rat

Abstract

The physiological role of melanin-concentrating hormone (MCH) in mammals is still very elusive, but this peptide might participate in the central control of the hypothalamopituitary adrenal (HPA) axis during adaptation to stress. Cloning and sequencing of the rat MCH (rMCH) cDNA revealed the existence of additional peptides encoded into the MCH precursor. Among these peptides, neuropeptide (N) glutamic acid (E) isoleucine (I) amide (NEI) is co-processed and secreted with MCH in rat hypothalamus. In the present work we examined: (1) The pattern of rMCH mRNA expression during the light and dark conditions in the rat hypothalamus and (2) The effect of intracerebroventricular (ICV) injections of rMCH and NEI in the control of basal or ether stress-modified release of corticotropin (ACTH), prolactin (PRL) and growth hormone (GH) secretion in vivo in light-on and light-off conditions. Our data indicate that rMCH mRNA levels do not change during the light-on period, but increase after the onset of darkness. Either alone or co-administered, rMCH and NEI do not modify basal secretion of GH and PRL at any time tested nor do they alter ether stress-induced changes in these two hormonal secretions. At the end of the light on period corresponding to the peak of the circadian rhythm in ACTH, administration of rMCH but not NEI leads to a decrease in ACTH levels while MCH is not effective during the light off period of the cycle (i.e. when basal ACTH levels are already low). Using a moderate ether induced stress, ACTH levels are only stimulated during the dark phase of the cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Melanin-concentrating hormone 1 receptor-deficient mice are lean, hyperactive, and hyperphagic and have altered metabolism

“…Plasma corticosterone levels were significantly greater in 6-7-month-old male Mch1r Ϫ/Ϫ mice relative to wild-type littermates (Table 1). This result is consistent with the finding that MCH administration reduces basal and stress-induced plasma adrenocorticotropic hormone levels in rats (24) and suggests that MCH1R may be involved in the regulation of adrenal function. Ci͞g of tissue; n ϭ 5 per genotype).…”

A possible role of neuropeptide Y, agouti-related protein and leptin receptor isoforms in hypothalamic programming by perinatal feeding in the rat

“…Trunk blood was collected in heparinised tubes, centrifuged immediately and the plasma separated and kept frozen at −20°C until assayed. Due to the presence of circadian changes in hypothalamic mRNA content of the neuropeptides evaluated in this study [26][27][28][29][30], the animals (NL, SL and LL) from each experiment (two independent experiments) were killed on the same day (18.00-20.00 hours), just before the dark phase (20.00 hours). In order to completely avoid any possible circadian effect, the animals were killed in an alternate manner, i.e., one rat from each group (NL, SL, LL), rather than all the animals from one experimental group before starting the next group.…”

Functional state of rat cardiomyocytes and blood antioxidant system under psycho-emotional stress

“…Apart from the processes described above, changes in many other metabolic processes also take places, which are vital for normal functionality of an organism. It has been found that stress results in quantitative changes in some hormones, such as glucocorticoid, catecholamin and melatonin [35,36]. Therefore, the objective of our current research is to establish the quantitative changes of the hormones under psycho-emotional stress, such as isolation and violation of circadian rhythm.…”