Effect of tuftsin on the orientation-exploratory behavior of normal white rats and against a background of pharmacologically induced disorders of the brain biogenic amine system

The application of "hole board" method showed that the endogenic immunostimulator tetrapeptide tuftsin injected intraperitoneally in dose 0.3 mg/kg has a short-time stimulating action on the orienting reaction of rats in 5 min, though in 24 hours it suppresses the registered behavioral indexes. The pharmacological analysis of the above studied phenomenon showed that catecholaminergic and especially dopaminergic brain systems played the leading role in tuftsin effect. Tuftsin can normalize animals' behaviour disturbed by the pharmacological agents, which slightly influence the functioning of the brain dopaminergic system.     

Influence of substance P on the behavioral changes induced by haloperidol in rats

Locomotor activity and grooming behavior of rats were recorded for a period of 30 min following intraventricular injections of substance P(SP) in doses of 0.60 and 2.50 microgram/rat. The lower dose of the peptide significantly increased locomotion for 10 min and time spent grooming for 25 min. The effects of the same two doses of SP on the hypokinesia induced by various pharmacological treatments modifying catecholaminergic systems were then examined. SP did not affect the behavioral depression produced by alpha-methyl-para-tyrosine (250 mg/kg), FLA-63 (25 mg/kg) and phenoxybenzamine (20 mg/kg). However, SP, in dose of 0.60 microgram/rat, systematically reversed the decrease in locomotor activity induced by a relatively small dose of haloperidol, 0.1 mg/kg. The dame dose of the peptide significantly counteracted the rigidity but not the hypokinesia and catalepsy resulting from the previous administration of a higher dose of haloperidol, 3 mg/kg. The results support the hypothesis that SP may exert direct or indirect function in motor behavior, possible via a modulatory action on brain dopaminergic systems.     

A comparative analysis of the morphochemical changes in the neurons of the visual and sensorimotor cortices and the nucleus accumbens of rats administered tuftsin

White rats were treated with a single administration of tetrapeptide tuftsin (Thr-Lys-Pro-Arg) in the dose 300 mcg/kg (b.w). Using interferometry, the protein content and concentration were assessed 15, 30 and 60 minutes after injection. The area of the neuron cytoplasm and nucleus were measured too. The nucleoplasmic balance and dispersion were calculated. Significant alterations in the protein contents and cellular area, nucleoplasmic balance and dispersion were detected in neurons of visual, sensomotor cortex and of n. accumbens. A possible interrelation is discussed between tuftsin action and the functional activity of neurons, between the level of their protein metabolism and establishment of emotional and motor response.     

Augmentation of cocaine hyperactivity in rats by systemic ghrelin

The feeding-relevant pathway by which food deprivation (FD) augments cocaine action is unknown. Systemic administration of the 28 amino acid acylated peptide ghrelin (1-10 nmol) increases food intake in rats and circulating levels of rat ghrelin are up-regulated by FD. The present experiment examined the impact of ghrelin or vehicle pretreatment on the locomotion and stereotypy induced by systemic cocaine hydrochloride. Male Sprague-Dawley rats were pretreated at -60 min with 0 or 5 nmol rat ghrelin (IP) and then injected (IP) at time 0 with 0, 2.5, 5.0, or 10.0 mg/kg cocaine. Locomotor activity was monitored over a 45-min post-cocaine period. Rats received the same ghrelin dose, but a different cocaine dose (in random order) on each of the four drug trials, with each drug trial separated by at least 2 days. Administration of 5 nmol ghrelin-0 mg/kg cocaine slightly increased locomotion relative to that of 0 nmol ghrelin-0 mg/kg cocaine. Cocaine increased locomotion as a function of dose in the 0 nmol ghrelin group, but the effect of cocaine was even greater when preceded by 5 nmol ghrelin. These results indicate that acute injection of ghrelin, at a feeding-relevant dose, augments the acute effects of cocaine on locomotion in rats.     

Serotonin content in different sections of the brain, liver, intestines and blood of rats predisposed and not predisposed to alcohol consumption

Experiments were made with white random-bred rats (males) exposed to ethanol. The content of serotonin measured by spectrofluorometry was higher in the hypothalamus, brain stem and intestine, and was lower in the thalamus, striatum liver and blood in the animals predisposed to voluntary alcohol consumption and with lateral position duration 62 +/- 18 min as compared with the animals not predisposed to alcohol consumption and with lateral position duration 196 +/- 23 min, the dose of ethanol being 4.5 g/kg i. p. Thirty minutes after ethanol administration in a dose of 2.5 g/kg i. p. to the alcohol-predisposed rats there was a lowering of the serotonin content in the hypothalamus and an increase in the thalamus, brain stem, liver and blood. Meanwhile in the rats not predisposed to alcohol consumption, the serotonin content rose in the hypothalamus, brain stem, liver, intestine and blood and fell in the thalamus and striatum. It is assumed that the serotoninergic system of the brain may play a role in the formation of "positive" or "negative" attitudes to ethanol in the population of white random-bred rats.     

Comparison between multiple behavioral effects of peripheral ethanol administration in rats: sedation, ataxia, and bradykinesia

Although low doses of systemic ethanol stimulate locomotion in mice, in rats the typical response to peripheral ethanol administration is a dose-dependent suppression of motor activity. In the present study, male rats received acute doses of ethanol IP (0.0, 0.25, 0.5, 1.0 or 2.0 g/kg) and were tested on several behavioral tasks related to the motor suppressive or sedative effects of the drug. This research design allowed for comparisons between the effects of ethanol on different behavioral tasks in order to determine which tasks were most sensitive to the drug (i.e., which tasks would yield deficits that appear at lower doses). In the first two experiments, rats were evaluated on a sedation rating scale, and ataxia/motor incoordination was assessed using the rotarod apparatus. Administration of 2.0 g/kg ethanol produced sedation as measured by the sedation scale, and also impaired performance on the rotarod. In a third experiment, ethanol reduced locomotion in the stabilimeter at several doses and times after IP injection, with 0.25 g/kg being the lowest dose that produced a significant decrease in locomotion. Finally, experiment four studied the effects of ethanol on operant lever pressing reinforced on a fixed ratio 5 (FR5) schedule for food reinforcement. Data showed suppressive effects on lever pressing at doses of 1.0, and 2.0 g/kg ethanol. Analysis of the interresponse time distribution showed that ethanol produced a modest slowing of operant responding, as well as fragmentation of the temporal pattern of responding and increases in pausing. Taken together, these results indicate that rats can demonstrate reduced locomotion and slowing of operant responding at doses lower than those that result in sedation or ataxia as measured by the rotarod. The detection of subtle changes in different motor test across a broad range of ethanol doses is important for understanding ethanol effects in other cognitive, motivational or sensory processes.     

The ethanol-induced open-field activity in rodents treated with isethionic acid, a central metabolite of taurine.

The effect of isethionic acid, a central metabolite of taurine, on ethanol-induced locomotor activity was investigated in rodents. Ten minutes following an (i.p.) simultaneous administration of ethanol (0.0, 1.5, 2.0, 2.5, 3.0, 3.5 g/kg) and isethionic acid (0.0, 22.5, 45.0, 90.0, 180.0 mg/kg), mice were placed in the open-field chambers and locomotor activity was measured during a ten-minute testing period. A significant interaction was found between isethionic acid and ethanol. Isethionic acid pre-treated mice (45.0, 90.0 and 180.0 mg/kg) showed a higher locomotor activity than the saline group at 2.5 and 3 g/kg of ethanol. In a second study, isethionic acid (45 mg/kg) and ethanol (1 g/kg) were simultaneously injected to rats. Ten minutes after the two treatments, rats were placed in the open-field chamber for a 30-minute period. The depressant effects that ethanol produced on rat locomotion were amplified by the same dose of isethionic acid as it affected ethanol-induced locomotion in mice (45 mg/kg). However, isethionic acid did not change the spontaneous locomotion at any of the doses tested in mice or rats. Since no differences in blood ethanol levels were detected in both mice and rats, the interaction between isethionic acid's action and ethanol-related locomotion does not seem to be due to different rates of absorption of ethanol or any other pharmacokinetic process related to ethanol levels. The current study displayed that isethionic acid, administered intraperitoneally, behaves in a similar way to its immediate precursor, taurine, by amplifying ethanol-induction of the locomotor activity.     

Comparative analysis of the morphochemical changes in the visual and sensorimotor cortical neurons of rats exposed to taftsin

White rats were treated with a single administration of immunostimulator tuftsin (Thr-Lys-Pro-Arg, in the dose 300 mcg/kg b. w.). By interferometry protein content and concentration and the area of neuron cytoplasm and nucleus were assessed 15 minutes after injection, significant alterations in protein content and cellular area were detected in one type neurons of visual and sensomotor cortex. A possible interrelation is discussed between tuftsin action and the functional activity of neurons, and between the level of their protein metabolism and establishment of emotional and motor response.     

Locomotion induced by non-contingent intracranial stimulation: comparison to psychomotor stimulant

Non-contingent experimenter-applied stimulation (nEAS) to the ventral mesencephalon, unlike contingent intracranial self-stimulation (ICSS), elicits high rates of general locomotion. This locomotion may be due to the nature of the presentation of stimulation, in that nEAS is non-contingent, while ICSS depends on a specific and focused response (e.g., bar pressing). Psychomotor stimulants also elicit high amounts of general locomotion, with the locomotion attributed to increased dopamine release. Interestingly, dopamine release decreases or is absent with repeated ICSS, but not nEAS. This suggests that the locomotion elicited by nEAS may be the result of DA release similar to that observed with psychomotor stimulants. To determine the relationship between locomotion induced by nEAS and psychomotor stimulants, locomotion elicited by nEAS was directly compared to that produced by cocaine, a psychomotor stimulant and indirect DA agonist. Six groups of rats were examined: (1) DA+ group: rats were implanted with a stimulating electrode in the ventral mesencephalon and activation of DA neurons was verified during surgery by monitoring DA release in the striatum; (2) DA- group: rats were also implanted with stimulating electrodes, but the location in the ventral mesencephalon did not elicit DA release; (3) 10-mg/kg cocaine group: rats were exposed to a low dose (10 mg/kg) of cocaine; (4) 40-mg/kg cocaine group: rats were exposed to a high dose (40 mg/kg) of cocaine; (5) saline group: rats were injected with saline; and (6) naive group: rats received no treatment. The topography of behavior was assessed in all rats during four periods: a pre-treatment baseline, treatment, early post-treatment, and a late post-treatment end point. The results suggest that locomotion elicited by nEAS was stereotypic, dependent upon DA release and similar, but not identical, to psychomotor stimulant-induced locomotion.     

Prolonged action of tuftsin in penicillin epilepsy]

The free behaviour experiments on rats showed during the first day the tuftsin-induced (0.3 mg/kg i. p.) increment of epileptic discharge in all the structures simultaneously. Open field behaviour depended on the sequence of penicillin and tuftsin injections. The rats with tuftsin used after the epileptiformic activity has been developed showed the behaviour analogical to the penicillin-injected animals. The preventive injections of tuftsin resulted in restoration of all behavioural indications by the third day. The optimal corrective effect has been obtained with tuftsin used preventively.     

八肽胆囊收缩素对大鼠心功能的影响及受体机制

为探讨八肽胆囊收缩素 (CCK 8)对麻醉大鼠心功能的影响及受体机制 ,实验监测了左心室收缩压(LVP)、左心室收缩与舒张期内压变化的最大速率 (±LVdp/dtmax)、心率 (HR)和平均动脉压 (MAP)。结果如下 :小剂量CCK 8(0 4 μg/kg)可引起心动过速 ,MAP、LVP和±LVdp/dtmax轻度上升 ;中剂量CCK 8(4 μg/kg)和大剂量CCK 8(4 0 μg/kg)可引起心动过缓 ,MAP、LVP和±LVdp/dtmax显著增加 ;应用CCK 受体 (CCK R)拮抗剂丙谷胺 (1 0mg/kg)抑制以上变化 ;由逆转录 聚合酶链反应 (RT PCR)检测到心肌组织有CCK A受体 (CCK AR)和CCK B受体 (CCK BR)mRNA表达。以上结果提示 :CCK 8可激活心肌组织的CCK R ,引起剂量依赖性的心功能增加和心率改变。     

Effects of acute central and peripheral administration of nicotine on ascending dopamine pathways in the male rat brain. Evidence for nicotine induced increases of dopamine turnover in various telencephalic dopamine nerve terminal systems

The actions of intraventicular injections and intravenous infusions of nicotine were studied on dopamine stores and turnover in discrete areas of the forebrain of normal male rats. This was done by measuring the decline of the dopamine stores after tyrosine hydroxylase inhibition using alpha-methyl-tyrosine methyl ester (H44/68). The dopamine concentrations in the various telencephalic dopamine nerve terminal systems were measured using the Falck-Hillarp methodology involving quantitative microfluorimetry. The catecholamine concentrations in the anteromedial frontal cortex were measured biochemically using high pressure liquid chromatography combined with electrochemical detection. Intraventricular experiments. The dopamine levels in discrete areas of nuc. caudatus and nuc. accumbens were significantly reduced even with the lowest dose of nicotine (1 microgram/rat). Intraventricular injections of nicotine in a dose of 100 microgram/rat produced significant increases of dopamine turnover in various types of dopamine nerve terminal systems in the nuc. caudatus, nuc. accumbens and tuberculum olfactorium, and following a dose of 10 microgram/rat increases of dopamine turnover were observed in the medial part of the nuc. caudatus. Furthermore, nicotine (100 microgram/rat) significantly increased noradrenaline but not dopamine turnover within the anterofrontal cortex. Intravenous experiments. The dopamine levels were selectively reduced by nicotine (1000 microgram/kg) in the cholecystokinin positive and negative dopamine nerve terminal systems of the nuc. accumbens. On the other hand, dopamine levels in the anteromedial frontal cortex were increased after this dose of nicotine. Intravenous infusions of nicotine (10-1000 microgram/kg) produced dose-related increases of dopamine turnover in the various dopamine nerve terminal systems analysed in the telencephalon. These effects became significant with a dose of 1000 microgram/kg/h. The dopamine terminals in the nuc. caudatus showed a higher sensitivity to intravenous infusions of nicotine, being affected by 10-100 microgram/kg of nicotine. These findings suggest that relatively low dose of nicotine via an activation of central nicotine-like cholinergic receptors can reduce dopamine concentration and increase dopamine turnover in discrete limbic and striatal areas. These actions may in part represent the neurochemical basis for the rewarding actions of nicotine and for nicotine dependence in man.     

Control in vivo of rat liver phosphofructokinase by glucagon and nutritional changes.

Glucagon (250 microgram/kg body wt.) intravenously injected into normal fed rats produces within 5 min a marked inactivation of liver phosphofructokinase, only observed when the enzyme activity is measured at subsaturating concentrations of fructose 6-phosphate. Since half-maximal inactivation is observed at a dose of glucagon of 0.32 microgram/body wt., a dose within the range of the physiological concentrations of the hormone, the inactivation of phosphofructokinase can occur in vivo in response to physiological changes in the concentration of glucagon. In gluconeogenic conditions (starved rats or high-protein-diet-fed rats), there is a marked inactivation of liver phosphofructokinase at subsaturating concentrations of fructose 6-phosphate similar to that found in normal fed rats after glucagon treatment. In these gluconeogenic conditions a 50% decrease in the Vmax. of the enzyme is also observed. No significant changes in phosphofructokinase activity either at subsaturating concentrations of fructose 6-phosphate or in the Vmax. of the enzyme are observed when rats are fed on a high-carbohydrate diet. In the last dietary condition, glucagon treatment produces similar effects to that described in the normal fed rats. Similar results have been obtained in the above condtions for pyruvate kinase L activity when measured at subsaturating concentrations of phosphoenolpyruvate.     

Inhibitory effects of 1 alpha, 25-dihydroxycholecalciferol on parathyroid hormone secretion in rats

In an attempt to study the influence of vitamin D metabolites on PTH secretion, serum calcium and urinary excretion of cAMP were sequentially measured in conscious perfused rats, and the effects of a single iv injection of the metabolites on these parameters were examined. Four hours after the administration of 0.25 microgram/kg (0.6 nmol/kg, probably a physiological dose) of 1 alpha, 25-dihydroxycholecalciferol [1 alpha, 25 (OH)2D3], the urinary excretion of cAMP decreased to a level compatible with that of parathyroidectomized rats (approximately 60% of the initial value; P less than 0.05) and this level was sustained for nearly 24 h. Serum concentrations of calcium (total and ionized) did not change. In parathyroidectomized rats which were continuously infused with bovine PTH (1 U/h), the vitamin D metabolite had no significant effect on the urinary excretion of cAMP. 24 R, 25-dihydroxcholecalciferol (12.5 microgram/kg) had no significant effect either on the urinary excretion of cAMP or on serum calcium. These results suggest that in rats, a physiological dose of 1 alpha, 25(OH)2D3 inhibits PTH secretion without causing a significant rise iu serum calcium, reflecting a feed-back mechanism between active vitamin D metabolite, 1 alpha, 25(OH)2D3 and the parathyroid glands.     

Tuftsin: a naturally occurring immunopotentiating factor. I. In vitro enhancement of murine natural cell-mediated cytotoxicity

Tuftsin is a physiologic tetrapeptide, which has recently been shown to possess immunoadjuvant properties including the stimulation of macrophage and granulocyte phagocytosis, migration, bactericidal, and tumoricidal activities. Tuftsin has also been reported to possess in vivo immunologically mediated anti-tumor potential. To determine the potential role of tuftsin as an antineoplastic immunoadjuvant, the in vitro effects of tuftsin on murine natural cell-mediated cytotoxicity were studied. We observed that in vitro treatment of mouse splenic effector cells with synthetic tuftsin induced a pronounced enhancement of natural killer cell (NKC) cytotoxicity against the T cell lymphoma Yac-1. The magnitude of NKC enhancement was directly dependent upon the concentration of tuftsin employed, with maximum NKC stimulation observed at tuftsin concentrations of 50 to 100 microgram/ml. The tuftsin induced enhancement of NKC activity was not strain specific, since equivalent stimulation was seen in CBA/J, C56BL/10, and DBA/2 mice. Elimination of macrophages, monocytes, T cells, and immunoglobulin-bearing cells had no effect on the dose-dependent tuftsin stimulation of natural cell-mediated cytotoxicity; thus the characteristics of the effector cells activated by tuftsin were consistent with those reported for NKC. We also observed that treatment of splenic effector cells with tuftsin prolonged the cytotoxic capabilities of these cells beyond 18 hr.     

Effect of treatment with submaximal and excessive doses of caerulein on pancreatic growth in newborn rats

Different groups of CFY female newborn rats were treated with saline, or 1 microgram/kg or 100 micrograms/kg doses of caerulein given s. c. 3 x/day. Application of 100 micrograms/kg dose of caerulein for 3 days stimulated pancreatic growth inducing pancreatic hyperplasia; both (1 and 100 micrograms/kg) doses evoked increase in trypsin/DNA ratio inducing pancreatic hypertrophy in 4-days-old rats. Using the indices as before application of 1 microgram/kg caerulein for 10 days stimulated pancreatic growth and both (1 and 100 micrograms/kg) doses elicited glandular hypertrophy in 11-days-old rats. In 24-old-rats the 1 microgram/kg doses of caerulein given for 3 days stimulated pancreatic growth and induced pancreatic hypertrophy, the 100 micrograms/kg doses of the peptide given for 3 days, however, evoked pancreatic aplasia and atrophy.     

Transplacental penetration of 7,12-dimethylbenz(a)anthracene and its distribution in the organs of rat fetuses]

Rats were given 7,12-dimethylbenz(a)anthracene (DMBA) intravenously in a dose of 15 mg/kg on the 21st day of pregnancy; its content in the liver, placenta, and the fetus was determined by the fluorescent-spectral method. The maximal concentration was reached in 10--15 min in the liver and placenta of the pregnant rats (45 and 6.3 microgram/kg, respectively) in comparison with a slower (in one hour) elevation in the fetal tissues (2.4 microgram/kg). It took about 5 hours for all the tissues to be cleared of the carcinogen. One hour after the administration DMBA was unevenly distributed in various fetal organs--the maximal content in the liver, and the minimal--in the "carcass" in comparison with the content in other organs (the kidneys, lungs, brain, intestine). The results obtained failed to correlate with the data on the predominant origination of the tumours in the kidneys and the nervous system of rats in transplacental DMBA action.     

Dose-dependent entrainment of rat circadian rhythms by daily injection of melatonin

Previous work in our laboratory has shown that daily injection of large doses of the pineal hormone melatonin entrains the free-running locomotor rhythms of rats held in constant darkness and synchronizes the disrupted patterns of rats maintained in constant bright light. The present experiments determined the dose-response characteristics of entrainment to daily melatonin injections and made preliminary biochemical estimates of blood melatonin levels and half-lives after two critical doses of the hormone. The data indicated that the median effective dose for melatonin as an entraining agent in free-running rats was 5.45 +/- 1.33 micrograms/kg, considerably lower than doses previously employed and lower than doses employed in reproductive and metabolic studies in rats and hamsters. The data further indicated that the response to melatonin was quantal; rats either entrained to melatonin or they did not. No "partial entrainment" was evident, nor were there differences in phase angle, activity, or period among all effective doses. Biochemical estimates of blood melatonin after either 1 mg/kg or 1 microgram/kg of melatonin indicated that all effective doses resulted in supraphysiological levels of blood melatonin, although doses of 1 microgram/kg resulted in blood levels that were within one order of magnitude of normal nighttime values. Together, the data suggest that the rat circadian system is sensitive to the pineal hormone melatonin at or below doses required to effect rodent reproduction. Whether this sensitivity reflects a role for the pineal gland in rat circadian organization, however, still remains to be determined.     

Effect of adrenalectomy and corticosterone on cocaine-induced sensitization in rats.

Effects of adrenalectomy (ADX) and corticosterone (CORT) on the development and expression of sensitization to the locomotor effect of cocaine (COC) were studied in rats. Sensitization was evoked by 5 daily injections of COC (10 mg/kg) and measured after a challenge dose of the drug (10 mg/kg) after a 5-day withdrawal (on day 10 of the experiment). ADX, performed before the start of COC administration, completely blocked the manifestation of COC-induced sensitization. In contrast, ADX performed on animals already sensitized to COC did not affect the sensitized locomotor activity response to a challenge dose of COC (on day 18). Pretreatment with CORT, 10 mg/kg, but not 5 mg/kg, before each of the 5 daily COC injections facilitated the development of COC sensitization, tested after a 5-day withdrawal. When pretreated with CORT alone (10 mg/kg), the challenge dose of COC administered on day 10 induced cross-sensitization to CORT. CORT (10 mg/kg) injected acutely before COC on day 10, potentiated the expression of COC sensitization. When given alone, on day 10 CORT (5-10 mg/kg) induced an increase in the locomotor activity of rats pretreated daily (5 injections) with COC. No drug treatment induced conditioned locomotion, as measured after saline challenge on day 8. Our results indicate that CORT facilitates the development and expression of COC sensitization, while ADX blocks the initiation of the behavioral phenomenon only. Moreover, there takes place cross-sensitization between CORT and COC, which indicates a close relationship between the drug-related mechanism and behavioral sensitization.     

Endotoxin-tolerant rats are still protected from oxygen toxicity by low-dose endotoxin treatment

To determine if we could reduce endotoxin's potential for toxicity, we produced "endotoxin-tolerant" rats by administering progressively increasing daily doses of endotoxin (10 ng, 100 ng, 1 microgram, 10 micrograms/kg). This dosage regimen produced a high degree of tolerance to the toxic actions of endotoxin: whereas only 3/17 (18%) of control rats survived a normally lethal dose of endotoxin (25 mg/kg), survival for the endotoxin-tolerant rats was 16/16. When endotoxin-tolerant rats received a standard protective dose of 500 micrograms/kg endotoxin just before transfer to 96-98% O2, 19/20 survived the 72-h exposure period vs. 20-30% survival for controls. Thus whereas the endotoxin-tolerant state blocked the tested lethal and toxic effects of endotoxin, it did not nullify the O2 protective action of endotoxin. In addition, endotoxin's stimulatory effects on the lung antioxidant enzymes in the 96-98% O2-exposed rats was also not blocked by the endotoxin-tolerant state. Thus the therapeutic ratio (TR) of endotoxin as an experimental pharmacological treatment against O2-induced lung damage has been markedly enhanced (TR = ratio of dose producing beneficial effects to dose producing toxic effects).