Recovery of impaired respiratory activity in cats by thyroliberin analog (PR-546) devoid of hormonal properties

Synthetic analogue thyroliberin (PR-546) devoid of hormonal activity, recovered respiration in conditions of hyperventilation, two-sided vagotomy and hypoxia, caused by the 40-70% bleeding. PR-546 (in doses 100-500 micrograms/kg) intravenously injected was shown to abolish diagram activity decreased effect after hyperventilation. Injection of PR-546 to vagotomized cats in 1.5-2 h, increased breathing rate. The breathing activity resumed after long breaks in respiration as a result of peptide injection. The responses to analogue introductions is similar to the thyroliberin effect.     

Morphine inhibits TRH-induced gastric contractile activity.

This study investigated the effect of centrally and peripherally administered thyrotropin releasing hormone (TRH) on gastric contractile activity of rats 14, 21, 28 and adult (greater than or equal to 50) days (D) of age, and the effect of morphine pretreatment on that response. Rats were anesthetized with urethane, then a tension transducer was implanted on the anterior gastric corpus. Following baseline recording, rats were pretreated with intraperitoneal morphine (2 mg/kg). TRH (5 micrograms) in saline or saline alone (0.6 microliters) was then injected into the cisternum magnum. Additionally, dose response to TRH was examined in 14- and 50-day-old rats. Intracisternal TRH induced a dose-related increase in gastric contractile activity in both 14- and 50-day-old rats. Higher doses of TRH (10 and 30 micrograms) prolonged the response as compared to low doses. Peripheral morphine pretreatment blocked the TRH-induced increase in gastric contractile activity in all age groups although a higher morphine dose (10 mg/kg) was needed to block the effect in 28D rats. Intravenous TRH (5, 10, 30 micrograms) produced an increase in gastric contractile activity in 14D rats which was blocked by vagotomy.     

Potentiation of the behavioral effects of pentobarbital, chlordiazepoxide and ethanol by thyrotropin-releasing hormone

Effects of pentobarbital, chlordiazepoxide and ethanol were studied alone and in combination with thyrotropin-releasing hormone (TRH), IM, on punished behavior. Key-peck responses of pigeons were maintained by food presentation under a fixed-interval 3-min schedule in which every 30th response produced shock. Moderate doses of pentobarbital, chlordiazepoxide and ethanol increased punished responding to 150-200% of control values while the higher doses of these drugs almost completely eliminated responding. TRH (0.01-1 mg/kg) had little effect on punished responding and 3 mg/kg produced 50% decreases. Although the lower doses of TRH were without effect when given alone, doses of 0.03 mg/kg and greater markedly potentiated the rate-increasing effects of pentobarbital, chlordiazepoxide and ethanol. Increases in punished responding of 350% were obtained with combinations of TRH and these drugs. The rate-decreasing effects of the sedative-hypnotic and anxiolytic compounds were not reversed by TRH. Potentiation of the behavioral effects of sedative-hypnotic and anxiolytic drugs by TRH suggests that TRH may play an important role in modulating the behavioral effects of these compounds and that combinations of neuroactive peptides with certain psychotherapeutic agents may be of some therapeutic value.     

Behavioral changes induced by the thyrotropin-releasing hormone analogue, RGH 2202

The behavioral activity of the thyrotropin-releasing hormone (TRH) analogue, L-6-ketopiperidine-2-carbonyl-leucyl-L-prolinamide (RGH 2202), has been studied in the rat. The number of errors in a radial maze test was reduced after acute intraperitoneal (IP) injection of RGH 2202 at the dose of 5 or 10 mg/kg. Grooming activity was increased with a lower dose, 1 mg/kg. Hypoxia-induced amnesia, as assessed with active and passive avoidance behavior tests, was reversed in rats treated with 5 or 10 mg/kg of the drug. The loss of learning and memory capacity shown by aged rats in the same behavioral tests was also reduced after injection of RGH 2202. In a test for sexual activity of male rats, the higher dose of the drug induced a facilitation of mounting and ejaculations, while smaller doses were ineffective. The rotorod test revealed a decreased number of falls in animals treated with 5 or 10 mg/kg of RGH 2202. In all behavioral tests, the same doses of natural thyrotropin-releasing hormone (TRH) were less effective, indicating that this analogue may be qualified as a potentially active drug in human pathologies.     

Thyroliberin and its analog lacking hormonal properties stimulate respiratory center activity in the frog Rana temporaria

It has been shown that thyroliberin and its synthetic analogue PR-546 injected into the lymphatic sacs (4.10(-7)-4.10(-9) g/kg) or applied to the medulla oblongata in the bulbar frogs (4.10(-10)-4.10(-12) g/kg) significantly increase the rate of motor respiratory volleys in the hypoglossal nerve. In preparations with the irregular level of the activity of the respiratory center, these drugs enhanced stabilization of the initial level of the rhythm of motor respiratory discharges.     

Pharmacological analysis of anti-inflammatory effects of low-intensity extremely high-frequency electromagnetic radiation

The anti-inflammatory effect of low-intensity extremely high-frequency electromagnetic radiation (EHF EMR, 42.0 GHz, 0.1 mW/cm2) was compared with the action of the known anti-inflammatory drug sodium diclofenac and the antihistamine clemastine on acute inflammatory reaction in NMRI mice. The local inflammatory reaction was induced by intraplantar injection of zymosan into the left hind paw. Sodium diclofenac in doses of 2, 3, 5, 10, and 20 mg/kg or clemastine in doses of 0.02, 0.1, 0.2, 0.4, and 0.6 mg/kg were injected intraperitoneally 30 min after the initiation of inflammation. The animals were whole-body exposed to EHF EMR for 20 min at 1 h after the initiation of inflammation. The inflammatory reaction was assessed over 3 - 8 h after the initiation by measuring the footpad edema and hyperthermia of the inflamed paw. Sodium diclofenac in doses of 5 - 20 mg/kg reduced the exudative edema on the average by 26% as compared to the control. Hyperthermia of the inflamed paw decreased to 60% as the dose of was increased diclofenac up to 20 mg/kg. EHF EMR reduced both the footpad edema and hyperthermia by about 20%, which was comparable with the effect of a single therapeutic dose of diclofenac (3 - 5 mg/kg). The combined action of diclofenac and the exposure to the EHF EMR caused a partial additive effect. Clemastine in doses of 0.02-0.4 mg/kg it did not cause any significant effects on the exudative edema, but in a dose of 0.6 mg/kg it reduced edema by 14 - 22% by 5 - 8 h after zymosan injection. Clemastine caused a dose-dependent increase in hyperthermia of inflamed paw at doses of 0.02-0.2 mg/kg and did not affect the hyperthermia at doses of 0.4 and 0.6 mg/kg. The combined action of clemastine and EHF EMR exposure caused a dose-dependent abolishment of the anti-inflammatory effect of EHF EMR. The results obtained suggest that both arachidonic acid metabolites and histamine are involved in the realization of anti-inflammatory effects of low-intensity     

Reduction of inflammation in rats by diazepam: tolerance development

High doses of diazepam (10-20 mg/kg) were shown to reduce the volume of acute carrageenan-induced inflammatory paw edema in rats. This effect was not observed after adrenalectomy or long-term use of similar doses of diazepam. The present experiment was undertaken to analyze the effects of long-term (21 daily injections) treatment with diazepam (10 mg/kg) on both carrageenan-induced paw edema (CIPE) and corticosterone serum levels. For comparison, the effects of a single and acute 10 mg/kg dose of diazepam were also analyzed. Results showed that: 1- long-term diazepam treatment induced no changes in CIPE values and corticosterone serum levels; 2- acute diazepam treatment reduced CIPE values and increased corticosterone serum levels; 3- the plasmatic levels of diazepam measured 1 hour after the single treatment or 1 hour after the last dose of long-term diazepam administration were not different. These results indicate the development of tolerance to diazepam effects on both CIPE and corticosterone serum levels and suggest a relevant role for corticosterone on diazepam-induced inhibition of acute inflammation. Data were discussed in the light of peripheral benzodiazepine receptor site (PBR) activation within adrenal gland cells by diazepam, thereby increasing the serum levels of corticosterone and thus reducing CIPE. Possible actions of diazepam on HPA axis activity and/or on cytokine network were also discussed.     

Characteristics of the neuromodulating effect of peripherally administered thyroliberin on the rat brain

The study of TRH effect on monoaminergic processes (MP) in the rat brain areas (hypothalamus, striopallidar system, cortex) was carried out upon intramuscular administration of TRH in doses of 1, 5 and 10 mg/kg 0.5, 1 and 3 h after TRH injections the animals were decapitated. TRH was shown to elicit persisting (3 h) multidirectional MP alterations in catecholaminergic system and unidirectional alterations in serotoninergic system (mainly acceleration of serotonin turnover). The most marked influence is produced by the lowest TRH dose, 1 mg/kg. It is suggested that in spite of a short half-life (2-5 min) TRH is able to act as a modulator on different target points of the rat MP pathways. That could be one of the possible explanations of previously observed prolonged TRH-induced pharmacological and clinical effects.     

Anti-inflammatory activity of licochalcone A isolated from Glycyrrhiza inflata

Licochalcone A was isolated from the roots of Glycyrrhiza inflata and evaluated for its anti-inflammatory activity in xylene-induced mice ear edema and carrageenan-induced paw edema tests. At the same time, the inhibition of prostaglandin biosynthesis by licochalcone A was also studied in lipopolysaccharide (LPS)-induced mouse macrophage cells. At 5 mg/ ear, licochalcone A showed remarkable effects against acute inflammation induced by xylene, and at the doses of 2.5, 5, 10 mg/kg (p.o.), licochalcone A reduced significantly paw edema induced by carrageenan compared to the control at the fourth hour. Both COX-2 activity and expression were significantly inhibited by licochalcone A at all the test doses. Therefore, licochalcone A could be a useful compound for the development of new anti-inflammatory agents.     

Effect of morphine on breathing and behavior in fetal sheep

To define the dose response of apnea and breathing to morphine we studied 12 fetuses at 116-141 days of gestation using our window technique. We instrumented the fetus to record electrocortical activity (ECoG), eye movements (EOG), diaphragmatic activity (integral of EMGdi), heart rate, carotid blood pressure, and amniotic pressure. Saline and morphine in doses of 0.03, 0.1, 0.5, 1, and 3 mg/kg were injected in random order in the jugular vein of the fetus during low-voltage ECoG. Fetuses were videotaped for evaluation of fetal behavior. We found 1) that saline did not elicit a response; 2) apnea, associated with a change from low- to high-voltage ECoG, increased from 2.2 +/- 1.5 (SE) min in two fetuses at a dose of 0.03 mg to 20 +/- 6.3 min in seven fetuses at 3 mg/kg (P less than 0.005); 3) the length of the breathing responses, associated with a change from high- to low-voltage ECoG, were 15 +/- 1.8 and 135.9 +/- 18.1 min (P less than 0.0005); 4) integral of EMGdi X frequency, an index equivalent to minute ventilation, increased from 1,763 +/- 317 arbitrary units to 10,658 +/- 1,843 at 1.0 mg/kg and then decreased to 7,997 +/- 1,335 at 3.0 mg/kg. These changes were related to a steady increase in integral of EMGdi, whereas frequency decreased at 3 mg/kg. There was an increase in breathing response to morphine plasma concentrations or morphine doses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Study of the topical anti-inflammatory activity of Achillea ageratum on chronic and acute inflammation models

We have produced a chloroform extract from Achillea which includes stigmasterol and sitosterol. By comparing it with the pure compounds an anti-inflammatory effect (with mouse ears) is assumed. The topical anti-inflammatory effect of the chloroform extract from Achillea ageratum (Asteraceae) and of stigmasterol and beta-sitosterol, isolated of this extract has been evaluated, against to 12-0-tetradecanoylphorbol acetate (TPA)-induced mouse ear edema, using simple (acute model) and multiple applications (chronic model) of the phlogistic agent. Myeloperoxydase activity also was studied in the inflamed ears. In the acute model the extract exerted a dose-dependent effect. All the doses assayed (1, 3 and 5 mg/ear) significantly reduced the edema (50%, 66% and 82%, respectively). The isolated sterols stigmasterol and beta-sitosterol (with doses of 0.5 mg/ear) had similar effect as the extract with doses of 1 and 3 mg (59% and 65% respectively). In the chronic model the anti-inflammatory effect generally was a more moderate one. The highest dose of the extract decreased the edema reduction to 26% with the highest dose of the extract applied. With the compounds the effect decreased to 36% with stigmasterol, and 40.6% with beta-sitosterol. Myeloperoxydase activity (MPO) was reduced by the extract and the compounds in the acute model, however, in the chronic edema, the enzyme inhibition was very weak with all treatments even with the standard substance. These results indicate that the chloroform extract of Achillea ageratum and some of the its components stigmasterol and beta-sitosterol are more effective as topical anti-inflammatory agents in acute than in the chronic process and their action is markedly influenced by the inhibition of neutrophil migration into inflamed tissue.     

Thyrotropin releasing hormone in the pancreas of newborn rats from streptozotocin-treated mothers

The effect of maternal diabetes (induced by i.p. injections of 40-50 mg/kg BW Streptozotocin on the day of mating) on TRH in the pancreas of newborn rats was studied. Determination of peptide alpha amidation activity and TRH precursor level on the day of birth revealed decreased biosynthesis of TRH resulting in profoundly (10 times) lower pancreatic TRH and TRH-OH concentrations in pups of diabetic rats. Pancreatic His-Pro-diketopiperazine (His-Pro-DKP) remained unaffected by maternal diabetes. The depression of pancreatic TRH was less profound 24 h later, and even elevated TRH was measured in the pancreas of pups of diabetic mothers on postnatal day 5. Short term postnatal starvation or nursing of intact pups by the diabetic foster mother did not affect pancreatic TRH. It could be postulated that postnatal TRH development in the rat pancreas is retarded by maternal diabetes, while His-Pro-DKP remains unaltered.     

Pharmacological assay of Cordia verbenacea V: oral and topical anti-inflammatory activity, analgesic effect and fetus toxicity of a crude leaf extract

Cordia verbenacea D.C. (Borraginaceae) is a perennial bush plant that grows widely along the southeastern coast of Brazil. Its leaves have been used in folk medicine for their anti-ulcer, anti-inflammatory and cicatrizing activities. We have already described the anti-inflammatory properties of C. verbenacea and its low toxicity in different acute animal models. In the present study, we investigated the anti-inflammatory activity in sub-chronic animal models of a crude leaf lyophilized extract when administered by oral route or topically applied, and concomitantly, its analgesic potency and toxicity to the fetus. Topical administration of the extract inhibited nystatin-induced edema proportionally to the doses used, and this effect at a dose of 4.56 mg/kg body wt. was similar to that observed with 6.0 mg/kg body wt. of naproxen. In miconazole-induced edema, the leaf extract at a dose of 1.24 mg/kg body wt., orally administered, has a very similar effect as compared to nimezulide (2.5 mg/kg body wt.) and dexamethasone (0.2 mg/kg body wt.). At an oral dose of 2.48 mg/kg body wt. the extract showed a very low analgesic effect, and total absence of fetus toxicity at doses of less than 7.44 mg/kg body wt.     

The central effects of morphine on fetal breathing movements in the fetal sheep

The fetal respiratory and electrocortical effects of 0.6 microgram to 600 micrograms of morphine, administered into the lateral cerebral ventricle, have been studied in chronically catheterised, unanaesthetized fetal sheep at 115-135 days gestation. Morphine at 0.6 microgram had no effect on breathing movements or electrocorticographic activity, and at 6 micrograms induced a period of apnoea (43-122 min) but had no effect on electrocortical activity. Intravenous naloxone (2 mg bolus and infusion of 2 mg/kg/h for 2 h) to the fetus had no effect on this apnoea. Morphine at 60 micrograms induced an initial period of apnoea (30-65 min) followed by episodic but significantly deep breathing movements with no effect on electrocortical activity and at 600 micrograms induced an initial period of apnoea (22-95 min) which was followed by deep, irregular and continuous (126-302 min) breathing movements. During the apnoea electrocortical activity initially remained cyclic, but as apnoea progressed there was a gradual reduction in the voltage of the electrocorticogram to a low voltage state. Intravenous naloxone (2 mg bolus and infusion of 2 mg/kg/h for 2 h) reversed both the respiratory and electrocortical effects. The hyperventilation was also inhibited by hypoxia. Naloxone alone had no effect on fetal breathing activity.     

Preliminary evaluation of anti-inflammatory and anti-arthritic activity of S. lappa, A. speciosa and A. aspera.

Saussurea lappa, Argyreia speciosa and Achyranthes aspera are well known Indian medicinal plants used in the indigenous systems of medicine for the treatment of inflammatory conditions. The ethanolic extracts of the plants at the doses of 50, 100 and 200 mg/kg, p.o. were screened for their effect on acute and chronic inflammation induced in mice and rats. S. lappa and A. speciosa were found to significantly inhibit paw edema induced by carrageenan and Freund's complete adjuvant and to prevent accumulation of inflammatory cells in carrageenan-induced peritonitis at doses of 50-200 mg/kg. A. aspera inhibited these inflammatory responses at doses of 100-200 mg/kg. The studies reveal that the ethanolic extracts of S. lappa, A. speciosa and A. aspera possess anti-inflammatory and anti-arthritic activity and support the rationale behind the traditional use of these plants in inflammatory conditions.     

Oleic acid lung injury in sheep

Intravenous infusion of oleic acid into experimental animals causes acute lung injury resulting in pulmonary edema. We investigated the mechanism of oleic acid lung injury in sheep. In experiments with anesthetized and unanesthetized sheep with lung lymph fistulas, we measured pulmonary arterial and left atrial pressures, cardiac output, lung lymph flow, and lymph and plasma protein concentrations. We injured the lungs with intravenous infusions of oleic acid at doses ranging from 0.015 to 0.120 ml/kg. We found that oleic acid caused reproducible dose-related increases in pulmonary arterial pressure and pulmonary vascular resistance, arterial hypoxemia, and increased protein-rich lung lymph flow and extravascular lung water. The lung fluid balance changes were characteristic of increased permeability pulmonary edema. Infusion of the esterified fat triolein had no hemodynamic or lung fluid balance effects. Depletion of leukocytes with a nitrogen mustard or platelets with an antiplatelet serum had no effect on oleic acid lung injury. Treatment of sheep before injury with methylprednisolone 30 mg/kg or ibuprofen 12.5-15.0 mg/kg also had no effects. Unlike other well-characterized sheep lung injuries, injury caused by oleic acid does not require participation of leukocytes.     

Pharmacological analysis of the antiinflammatory effects of low-intensity extremely-high-frequency electromagnetic radiation

The antiinflammatory effect of low-intensity extremely-high-frequency electromagnetic radiation (EHF EMR, 42.0 GHz, 0.1 mW/cm²) was studied in comparison to the effects of the antiinflammatory drug sodium diclofenac and the antihistamine clemastine in acute inflammatory reaction in mice of NMRI outbred stock. The local inflammatory reaction was induced by intraplantar injection of zymosan to the left hind paw. Intraperitoneal injections of 2, 3, 5, 10, and 20 mg/kg of sodium diclofenac or 0.02, 0.1, 0.2, 0.4, and 0.6 mg/kg of clemastine were made 30 min after the initiation of inflammation. An hour after the initiation of inflammation, animals were whole-body exposed to EHF EMR for 20 min. The inflammatory reaction was assessed 3–8 h after initiation by measuring the footpad edema and hyperthermia of the inflamed paw. Sodium diclofenac (5–20 mg/kg) reduced the exudative edema by ～26% compared to the control. Hyperthermia of the inflamed paw decreased by 60% with an increase in the diclofenac dose to 20 mg/kg. EHF EMR reduced both the footpad edema and hyperthermia by ～20%. This was comparable to the effect of a single therapeutic dose of diclofenac (3–5 mg/kg). The combination of diclofenac and exposure to EHF EMR produced a partial additive effect. Clemastine (0.02–0.4 mg/kg) did not affect the exudative edema, but at a dose of 0.6 mg/kg, edema was reduced by 14–22% five to eight hours after zymosan injection. Clemastine caused a dose-dependent increase in hyperthermia of inflamed paw at doses 0.02–0.2 mg/kg and did not affect the hyperthermia at doses 0.4 and 0.6 mg/kg. A combination of clemastine and EHF EMR exposure resulted in a dose-dependent abolishment of the antiinflammatory effect of EHF EMR. Our results suggest that both arachidonic acid metabolites and histamine are involved in the achievement of the antiinflammatory effects of low-intensity EHF EMR.     

Effects of thyrotropin-releasing hormone (TRH) and MK-771 on schedule-controlled behavior of squirrel monkeys, rabbits and pigeons

The effects of TRH (0.001-10.0 mg/kg) and a more potent TRH analog, MK-771 (0.001-5.6 mg/kg), were studied on comparable schedule-controlled performances of squirrel monkeys, rabbits and pigeons. Responding was maintained in the presence of different stimuli by a multiple fixed-ratio (FR), fixed-interval (FI) schedule of food presentation (monkeys and pigeons) or 0.25% saccharin solution (rabbits). Generally, TRH and MK-771 produced decreases in responding under both schedules and in all three species. TRH and MK-771 were roughly equipotent in the squirrel monkey, whereas in the pigeon and rabbit MK-771 was approximately 20 times more potent than TRH in decreasing responding to 50 percent of control levels. The duration of action of doses of TRH and MK-771 that reduced responding to 50 percent of control was approximately 3 hr in the squirrel monkey; recovery of performance occurred twice as fast under the FR schedules. With the pigeon, TRH effects that produced 50 percent decreases in responding lasted over 6 hours, whereas behaviorally comparable doses of MK-771 lasted about 4 hours. With few exceptions, TRH and MK-771 appear to produce similar effects of schedule-controlled behavioral performances of the squirrel monkey, rabbit and pigeon. Compared to the effects of other behaviorally-active substances under these procedures, TRH and MK-771 exert a distinctive array of effects.     

Corticotropin-releasing factor: an inhibitor of vascular leakage in rat skeletal muscle and brain cortex after injury

Corticotropin-releasing factor (CRF) and other peptides of the corticoliberin superfamily inhibit development of edema in skin and mucosa after noxious stimuli. Here, the breadth of CRFs protective activity on small blood vessels was examined after injury to skeletal muscle or to brain cortex. Male rats (243 +/- 15 g) were anesthetized with sodium pentobarbital 60 mg/kg i.p. and Monastral blue 60 mg/kg i.v. was injected 3 min before mechanical injury to muscle produced by a 4 cm midline surgical incision in the rectus abdominis or before freeze injury to the cortex produced by applying a cold probe (-50 degrees C) to the skull for 4 min. Vascular leakage, measured as area of dye staining multiplied by its light intensity, was quantified with an image-analysis system. CRF, having the human/rat sequence, 30 micrograms/kg s.c., injected once (30 min) or twice (30 min and 10 min) before injury to muscle or to brain, inhibited the lesion size by 58% and 55%, respectively (tissues taken at 0.5 and 1 h). Microscopy showed that CRF inhibited Monastral blue labeling of small blood vessels. The ED50 (95% C.L.) of CRF for reducing vascular leakage in muscle after celiotomy was 24 (9 to 64) micrograms/kg s.c. h/rCRF injected 30 micrograms/kg s.c. 2 h before celiotomy inhibited vascular leakage after celiotomy in adrenalectomized rats and this effect was not obtained with dexamethasone phosphate, 1 mg/kg s.c. alpha-Helical CRF (9-41), a CRF receptor antagonist, attenuated the actions of CRF on celiotomy. Laser-Doppler flowmeter measurements of skeletal muscle showed that the anti-inflammatory effects of CRF occurred when there were no significant concurrent changes in blood flow. From these results, we surmise that CRF has a versatile protective effect on small blood vessels when it inhibits leakage within different vascular beds.     

Evaluation of in vivo biological activity profile of isoorientin

Anti-nociceptive, anti-inflammatory and gastroprotective activities of the known C-glycosyl flavonoid, isoorientin, were studied in rats and mice. For the anti-nociceptive activity assessment the p-benzoquinone-induced writing test, for the anti-inflammatory activity the carrageenan-induced hind paw edema model in mice, and for the gastroprotective activity the EtOH-induced ulcerogenesis model in rats were used. Isoorientin was shown to possess significant anti-nociceptive and anti-inflammatory activities at 15 mg/kg and 30 mg/kg doses, without inducing any apparent acute toxicity as well as gastric damage. However, the compound did not possess any significant gastroprotective activity against EtOH-induced ulcerogenesis.