[Effect of chemical sympathectomy on myoelectric activity of the small bowel]. / Wplyw sympatektomi chemicznej na aktywnosc mioelektryczna jelit.

UNLABELLED: Central and peripheral noradrenergic system modulates myoelectric activity of the small bowel. Aim of this study was to evaluate the role of peripheral noradrenergic system in modulation of slow waves activity. Recordings of slow waves were performed on 20 conscious rats chronically fitted with 2 unipolar electrodes. After controls recording the animals were injected i.p. with 6-hydroxydopamine (6-OHDA--Sigma H8523) and the recording were performed on daily basis through the period of one month. RESULTS: The increase of frequency slow waves during the first week after 6-OHDA from 0.61 (+/- 0.11) to 0.71 (+/- 0.03), (p. < 0.05), and amplitude from 14468 +/- 11196 to 19128 +/- 5282 (microV)2 (p > 0.05) were observed. Variability in control recording was higher (SD +/- 0.11) than after 6-OHDA (SD 0.03). Next day diarrhoea after 6-OHDA occurred, persisted despite return normal myoelectric activity. Slow waves frequency gradually returns to control value after the fourth week. CONCLUSION: Peripheral noradrenergic system has a significant effect on the frequency and variability of slow wave and minor role on its amplitude but no on diarrhoea pattern.

[The role of leptin in metabolic regulation]. / Rola leptyny w regulacji metabolizmu.

Leptin discovery--the hormone derived from adipose tissue became a challenging event in understanding food intake and energy balance regulation. Leptin serum level correlates with fat stores and reacts according to changes in energy balance. Although leptin is thought of as a factor preventing obesity, in most of the cases obesity develops in association with increase in serum leptin level which indicates leptin resistance. It may be possible that the primary role of leptin is to mediate the signal for the switch between the starved and fed state. There is a lot of evidence that leptin has systemic effects apart from those related to energy homeostasis, including regulation of neuroendocrine, immune and reproductive function.

Involvement of nitric oxide in central histaminergic stimulation of the hypothalamic-pituitary-adrenal axis.

Brain histamine participates in central regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Endogenous nitric oxide (NO) modulates signal transduction of some neurotransmitters involved in activation of the HPA axis. In the present study we investigated whether endogenous NO and histaminergic systems in the rat brain interact in their regulation of ACTH and corticosterone secretion. Histamine (50 microg), histamine-trifluoromethyl-toluidide derivative (HTMT, 75 microg) a selective and potent H1-receptor agonist, and amthamine (75 microg) a H2-receptor agonist given intracerebroventricularly (i.c.v.) considerably increased ACTH and corticosterone secretion 1 h after administration. A potent and competitive inhibitor of rat brain neuronal NO synthase, (NOS), 7-nitroindazole (7-NI), given i.p. 15 min before histamine moderately increased the histamine-induced ACTH secretion and did not substantially alter the histamine-induced corticosterone secretion. Pretreatment with 7-NI totally abolished the HTMT-induced increase in ACTH and corticosterone secretion. The amthamine-evoked rise in ACTH secretion was moderately diminished and the amthamine-induced corticosterone secretion was not substantially altered by preatreatment with 7-NI. These results suggest that the histamine H -receptor transmited central stimulation of the HPA axis is considerably mediated by endogenous NO, whereas stimulation by histamine and via H2-receptor does not significantly depend on endogenous NO mediation.