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Histamine, serum prolactin and growth hormone in rats with long-term portacaval anastomosis
SELECTIVE
DETECTION
DEPENDENT TISSUE
G
OF HISTAMINE
PROTEIN
ACTIVITY
H, RECEPTORIN
RAT
HISTAMINE, SERUM PROLACTIN AND GROWTH HORMONE IN RATS WITH LONG-TERM PORTACAVAL ANASTOMOSIS V. Lozeva’, R. K. Tuominen3, E. Anttila’, M. Laitiner?, P. T. Miinnistb’, and L. Tuomisto’ 1Department of Pharmacology and Toxicology, ‘Department of Clinical Chemistry, University of Kuopio, 3Department of Pharmacy, University of Helsinki, Finland
BRAIN
SECTIONS
J.T. Laitinen Depamnent
and M. Jokinen of Physiology.
University
of Kuopio,
Finland
Histamine (HA) elicits its biological effects via three distinct G protein-coupled receptors, termed H,, HZ and H,. A novel approach of GTPy[“S] autoradiography was used here in order to visualize HA receptor-dependent G protein activity in rat brain tissue sections. In basal conditions, adenosine was present in sufficient concentrations to generate a prominent and widelydistributed adenosine A, receptor-dependent GTPy[?S] signal. Further incubations therefore contained DPCPX (IO” M), a selective A, receptor antagonist. HA (10~9-10~6M) elicited dosedependent increments in GTPy[?S] binding to discrete brain structures, most notably the striatum, cerebral cortex, and substantia nigra. The anatomical distribution of the HA-evoked binding response closely reflects known distribution of H, receptor binding sites and was fully mimicked by N”-methylHA, (R)a-methyl-HA and immepip, three H,-selective agonists. In all regions, the HA-evoked GTPy[%] signal was reversed with thioperamide and clobenpropit, two potent and selective H, antagonist whereas the H, antagonist mepyramine and the H2 antagonist cimetidine exhibned no potency. These data indicate that GTPy[“S] autoradiography selectively detects H, receptordependent signaling in response to HA stimulation. As this technique selectively reveals responses to G,,,-coupled receptors, our data suggest that the brain H, receptors signal through this inhibitory class of G proteins. Besides allowing more detailed studies on H, signaling within anatomically restricted regions of the CNS, GTP$%] autoradiography offers a novel approach for functional in vitro screening of novel H, ligands as well.
HISTAMINE AND NEOCORTICAL ACTIVITY IN RATS WITH ANASTOMOSIS V. Lozeva,
A. Valjakka,
E. Anttila,
Brain levels of histamine (HA) are dramatically increased after portacaval anastomosis (PCA) in the rat. Since HA is thought to modulate hormone release and feeding behaviour, we attempted to examine whether the weight loss and the possible changes in serum hormone levels in rats that six months previously had undergone PCA operation are HA related. Hypothalamus HA level was assayed by HPLC, serum prolactin (PRL) and growth hormone (GrH) levels by RIA. HA was significantly elevated in the PCA group (29.5 k 3.9 nmol/g vs. 4.9 + 0.3 nmol/g, p
THE EFFECT OF VASOACTIVE INTESTINAL PEPTIDE (VII’) ON THE LEVEL OF HISTAMINE AND I-METHYLHISTAMINE OF GASTRIC TISSUE OF RATS EXPOSED TO COLD-RESTRAINT STRESS. N. Tunpel , N. Erkasap’ , M. Tuncel” University f of Osmangazi Fat. of Medicine Dept. of Physiology , Universityof Anadolu Fat. of Pharmacy Dept. of Analytical Chemishy”, Eskipehir TURKEY
SLOW-WAVE PORTACAVAL
and L. Tuomisto
Department qf Pharmacology and Toxicology, University of Kuopio, Kuopio, Finland
??
Sleep disturbance is a classic symptom of portal-systemic encephalopathy (PSE) in humans. To assess the effects of experimental PSE on sleep patterns, we studied frontal cortex (FC) EEG properties in rats with portacaval anastomosis (PCA) six months after the operation. The levels of histamine (HA) and t-methylHA (t-MeHA) in FC were also assayed. A significant, nine-fold increase in the level of HA was observed in the PCA rats, accompanied by a less pronounced elevation in the concentration of tMeHA. PCA reduced the overall duration and spectral power of the synchronized, low frequency high amplitude FC EEG activity (delta waves and spindles). Whereas the PCA operation decreased the spectral power of both delta waves and thalamus regulated EEG spindles, only the duration of spindles was significantly reduced. Furthermore, a significant negative correlation existed between the levels of HA and the duration of spindles in the PCA group. We conclude that PCA in the rat results in increased arousal and alertness during the light period. We also suggest that, along with other factors, HA may play a role in the development of sleep disturbances in PSE.
Our previous study showed that cold-restraint stress induces gastric lesions and mast cell degranulation and also increases lipid peroxidation in gastric tissue of rats. However superoxide dismutase and catalase activities of tissue did not change. VIP prevented stress-induced ulcers, inhibited mast cell degranulation and protected gastric tissue from lipid peroxidation. In the present study, histamine and lmethylhistamine concentration were measured in gastric tissue of rats exposed to cold-restraint stress. 18 (SpragueDawley) rats (200-220 gr) of both sexes used. GI: Controls (n:6), GII: Cold-restraint stress; 4’ C for 3 hr (n:6), GIII: prior to stress 25 ng kg-’ VIP (IP) given. Gastric tissue histamine and 1-methylhistamine concentration were measured by HPLC. Although histamine concentration of gastric tissue did not change significantly 1-methylhistamine concentration significantly increased in stressed rat. Administration of VIP significantly decreased I-methylhistamine concentration to the control level. Our study suggest that gastric mast cells possibly release metilated histamine and that histamine may have a role in the development of gastric lesions during coldrestraint stress.
219
DETECTION
DEPENDENT TISSUE
G
OF HISTAMINE
PROTEIN
ACTIVITY
H, RECEPTORIN
RAT
HISTAMINE, SERUM PROLACTIN AND GROWTH HORMONE IN RATS WITH LONG-TERM PORTACAVAL ANASTOMOSIS V. Lozeva’, R. K. Tuominen3, E. Anttila’, M. Laitiner?, P. T. Miinnistb’, and L. Tuomisto’ 1Department of Pharmacology and Toxicology, ‘Department of Clinical Chemistry, University of Kuopio, 3Department of Pharmacy, University of Helsinki, Finland
BRAIN
SECTIONS
J.T. Laitinen Depamnent
and M. Jokinen of Physiology.
University
of Kuopio,
Finland
Histamine (HA) elicits its biological effects via three distinct G protein-coupled receptors, termed H,, HZ and H,. A novel approach of GTPy[“S] autoradiography was used here in order to visualize HA receptor-dependent G protein activity in rat brain tissue sections. In basal conditions, adenosine was present in sufficient concentrations to generate a prominent and widelydistributed adenosine A, receptor-dependent GTPy[?S] signal. Further incubations therefore contained DPCPX (IO” M), a selective A, receptor antagonist. HA (10~9-10~6M) elicited dosedependent increments in GTPy[?S] binding to discrete brain structures, most notably the striatum, cerebral cortex, and substantia nigra. The anatomical distribution of the HA-evoked binding response closely reflects known distribution of H, receptor binding sites and was fully mimicked by N”-methylHA, (R)a-methyl-HA and immepip, three H,-selective agonists. In all regions, the HA-evoked GTPy[%] signal was reversed with thioperamide and clobenpropit, two potent and selective H, antagonist whereas the H, antagonist mepyramine and the H2 antagonist cimetidine exhibned no potency. These data indicate that GTPy[“S] autoradiography selectively detects H, receptordependent signaling in response to HA stimulation. As this technique selectively reveals responses to G,,,-coupled receptors, our data suggest that the brain H, receptors signal through this inhibitory class of G proteins. Besides allowing more detailed studies on H, signaling within anatomically restricted regions of the CNS, GTP$%] autoradiography offers a novel approach for functional in vitro screening of novel H, ligands as well.
HISTAMINE AND NEOCORTICAL ACTIVITY IN RATS WITH ANASTOMOSIS V. Lozeva,
A. Valjakka,
E. Anttila,
Brain levels of histamine (HA) are dramatically increased after portacaval anastomosis (PCA) in the rat. Since HA is thought to modulate hormone release and feeding behaviour, we attempted to examine whether the weight loss and the possible changes in serum hormone levels in rats that six months previously had undergone PCA operation are HA related. Hypothalamus HA level was assayed by HPLC, serum prolactin (PRL) and growth hormone (GrH) levels by RIA. HA was significantly elevated in the PCA group (29.5 k 3.9 nmol/g vs. 4.9 + 0.3 nmol/g, p
THE EFFECT OF VASOACTIVE INTESTINAL PEPTIDE (VII’) ON THE LEVEL OF HISTAMINE AND I-METHYLHISTAMINE OF GASTRIC TISSUE OF RATS EXPOSED TO COLD-RESTRAINT STRESS. N. Tunpel , N. Erkasap’ , M. Tuncel” University f of Osmangazi Fat. of Medicine Dept. of Physiology , Universityof Anadolu Fat. of Pharmacy Dept. of Analytical Chemishy”, Eskipehir TURKEY
SLOW-WAVE PORTACAVAL
and L. Tuomisto
Department qf Pharmacology and Toxicology, University of Kuopio, Kuopio, Finland
??
Sleep disturbance is a classic symptom of portal-systemic encephalopathy (PSE) in humans. To assess the effects of experimental PSE on sleep patterns, we studied frontal cortex (FC) EEG properties in rats with portacaval anastomosis (PCA) six months after the operation. The levels of histamine (HA) and t-methylHA (t-MeHA) in FC were also assayed. A significant, nine-fold increase in the level of HA was observed in the PCA rats, accompanied by a less pronounced elevation in the concentration of tMeHA. PCA reduced the overall duration and spectral power of the synchronized, low frequency high amplitude FC EEG activity (delta waves and spindles). Whereas the PCA operation decreased the spectral power of both delta waves and thalamus regulated EEG spindles, only the duration of spindles was significantly reduced. Furthermore, a significant negative correlation existed between the levels of HA and the duration of spindles in the PCA group. We conclude that PCA in the rat results in increased arousal and alertness during the light period. We also suggest that, along with other factors, HA may play a role in the development of sleep disturbances in PSE.
Our previous study showed that cold-restraint stress induces gastric lesions and mast cell degranulation and also increases lipid peroxidation in gastric tissue of rats. However superoxide dismutase and catalase activities of tissue did not change. VIP prevented stress-induced ulcers, inhibited mast cell degranulation and protected gastric tissue from lipid peroxidation. In the present study, histamine and lmethylhistamine concentration were measured in gastric tissue of rats exposed to cold-restraint stress. 18 (SpragueDawley) rats (200-220 gr) of both sexes used. GI: Controls (n:6), GII: Cold-restraint stress; 4’ C for 3 hr (n:6), GIII: prior to stress 25 ng kg-’ VIP (IP) given. Gastric tissue histamine and 1-methylhistamine concentration were measured by HPLC. Although histamine concentration of gastric tissue did not change significantly 1-methylhistamine concentration significantly increased in stressed rat. Administration of VIP significantly decreased I-methylhistamine concentration to the control level. Our study suggest that gastric mast cells possibly release metilated histamine and that histamine may have a role in the development of gastric lesions during coldrestraint stress.
219