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Adrenergic innervation plays an important role in the control of electric activity and circulatory parameters of the gut. Importance of adrenergic system as a modulator of motor, neural and metabolic activity of the intestine is studied extensively but still not well understood. We use 6-OHDA a neurotoxin and a blocking agent of adrenergic fibers, to evaluate their exact role in the control of vital parameters of the intestine and vagal nerves. 50 Wistar rats were used. Animals were fasted 24 h prior to experiment with free access to water allowed. Acute experiments were performed on 30 rats, divided in the three groups. Four experimental groups were established. I--sham operated. II and III--pretreated with 6-ODHA (25 mg//kg/24 h s.c.) 3 days before experiment. IV group were used for chronic procedure. Thiopental anesthesia (Vetbutal Biovet) was applied. Animals were artificially ventilated with positive pressure rodent ventilator (Ugo Basile), and heated with continuous temperature control by rectal thermistor (FST). Left carotid artery was cannulated and connected with electro manometer--arterial pressure (AP) was expressed in mm Hg. Right jugular vein was cannulated for continuous saline administration 0.2 ml/h. Mesenteric blood flow (MBF) was recorded with use of ultrasonic probe (Transonic systems T206). Microcirculatory blood Flow (LDBF) was estimated by laser Doppler flowmetry (Periflux 2001 Master). Arterio-venous difference (AVO2) was estimated from whole blood (AVOXimeter 1000 E). Oxygen uptake was calculated from MBF and AVO2 and expressed in ml/min/100 g tissue. Chronic experiments were performed on conscious animals with electrodes implanted to the serosal surface of the intestinal wall. Measurements of intestinal myoelectric parameters were performed one, two and three weeks after 6-OHDA administration. Vagal activity was recorded in left vagus nerve in the neck with suction electrodes (one month after 6-OHDA). 6-OHDA pretreatment evoked increase of dominant slow wave frequency by 0.1 Hz from 0.62 +/- 0.10 to 0.74 (+/- 0.03) Hz in the first week after treatment (p < 0.05). Slow wave frequency was no markedly influenced in acute experiments. In the chronic experiments after initial increase gradual decrease of slow wave frequency was observed reaching control values of 0.62 +/- 0.17 Hz after 28 days. After 6-OHDA administration in chronic experiments no substantial changes in slow waves amplitude was observed. Frequency and amplitude of spikes activity in vagus nerve after sympatectomy increased from 7.96 +/- 1.3 to 10.3 +/- 2/min and 0.18 +/- 0.09 to 1.13 +/- 0.8/mV. Chemical denervation evoked increase of MBF and LDBF by 18 +/- 3.6% and 22 +/- 6.4% respectively. Intestinal oxygen uptake (VO2) was increased by 10.2 +/- 1.2% in comparison to control. Heart rate and arterial pressure was decreased by 18 +/- 4% and 12 +/- 2.4% respectively in comparison to control. Adrenergic system plays profound role in the modulation of both myoelectric and motor activity of the intestine in the rat. Continuous activity of adrenergic neurons affects vascular conductance, capillary density and oxygen diffusion parameters.

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.

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.

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.