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At least 811 records · Page 45Linked to original sources
PubMed1981

Role of sinoaortic reflexes in hemodynamic patterns of natural defense behaviors in the cat.

To evaluate whether sinoaortic afferents contribute to the hemodynamic pattern of fighting, cardiovascular changes associated with fighting were studied in cats before and after sinoaortic denervation. Sinoaortic denervation exaggerates the decrease in heart rate, cardiac output, and arterial pressure during immobile confrontation (hissing, staring but no movement). During nonsupportive fighting (fighting with forelimbs while lying on one side) and supportive fighting ( fighting while standing on four feet) sinoaortic denervation reduces the increase in heart rate and cardiac output, minimizes the mesenteric vasoconstriction, induces a fall in arterial blood pressure, but does not affect iliac vasoconstriction or vasodilatation. The hemodynamic pattern of fighting is similarly changed by temporary inactivation of carotid sinus baroreflexes by common carotid occlusion as by chronic section of sinoaortic nerves. It is concluded that sinoaortic reflexes play an important role in the cardiovascular patterns accompanying natural fighting. They favor cardiac action and allow a marked visceral vasoconstriction to occur, thus minimizing or preventing a fall in blood pressure during emotional behavior.

Aggression↗
PubMed1999

Effect of the H1-histamine receptor agonist betahistine on drinking and eating behavior in pygmy goats.

The effect of different doses of the H1-receptor agonist betahistine (0.9 and 2, 4 and 8 mg/kg b.wt.(0.75)) on water and food intake was investigated in 12 pygmy goats. Intraperitoneal (i.p.) injection of betahistine (2, 4, and 8 mg/kg b.wt.(0.75)) stimulated drinking in a dose-dependent manner. Food intake was decreased after the injection of 4 or 8 mg/kg b.wt.(0.75) betahistine, respectively. The increase in water intake was characterized by an increased draft size and decreased latency to drink. The decrease in food intake at the highest dose tested was characterized by an increased latency to eat and by a decreased meal frequency, and food intake associated to drinking was decreased. In line with previous studies, these results support the hypothesis that food-associated drinking is mediated by stimulation of H1-receptors of histamine in pygmy goats.

Animals↗
PubMed2004

A structural basis for the species-specific antagonism of 26,23-lactones on vitamin D signaling.

The 26,23-lactone derivative of 1alpha,25-dihydroxyvitamin D3, TEI-9647, is a partial antagonist of the of human vitamin D receptor (VDR). However, we found that TEI-9647 in rat cells behaves as a weak VDR agonist. This behavior could be mimicked in human cells by the double mutagenesis of human VDR (specifically C403S and C410N). The increased agonistic action of TEI-9647 correlates to a gain in the interaction of the VDR with coactivator protein and a decreased stabilization of the antagonistic conformation of the receptor. Molecular dynamics simulations indicated that TEI-9647 acts as antagonist of human VDR by reducing the stability of helix 12 of the ligand binding domain. In contrast, N410 of the rat VDR stabilized, via backbone contacts, the interaction between helices 11 and 12. This results in TEI-9647 becoming a weak agonist in this organism.

Amino Acid Sequence↗
PubMed2005

Behavioral effects of the novel cannabinoid full agonist AM 411.

AM 411 ((-)-1-adamantyl-Delta8-tetrahydrocannabinol) is a novel full agonist at cannabinoid CB1 receptors. The present studies were conducted to provide behavioral characterization of this compound in rats. It was hypothesized that AM 411 should produce behavioral effects similar to known cannabinoid agonists, and that these effects should be inhibited by co-treatment with a CB1 antagonist. In Experiments 1 and 2, AM 411 dose-dependently produced behaviors consistent with CB1 agonism, including analgesia, hypothermia, catalepsy and reductions in locomotion, which were blocked by a CB1-selective antagonist. In Experiment 3, AM 411 produced a dose-dependent suppression of lever-pressing on a fixed-ratio 5 (FR5) schedule, a task known to be sensitive to administration of CB1 agonists. Detailed analysis of the temporal patterns of operant responding showed that AM 411 altered the distribution of interresponse times. Experiment 4 showed that AM 411 decreased relative interior activity in the open field, which is suggestive of an anxiogenic effect. It is concluded that AM 411 produces CB1 agonist-like behavior with potency between that of WIN 55,212-2 and AM 356. AM 411 could be a useful tool for understanding the behavioral and neural effects of CB1 receptor stimulation.

Adamantane↗
PubMed1997

Effect of menstrual cycle phase on neuroendocrine and behavioral responses to the serotonin agonist m-chlorophenylpiperazine in women with premenstrual syndrome and controls.

To evaluate the potential role of serotonin in the premenstrual syndrome (PMS), we investigated the effects of menstrual cycle phase on neuroendocrine and behavioral responses to the serotonergic agent m-chlorophenylpiperazine (m-CPP) in women with PMS and controls. A single oral dose of m-CPP (0.5 mg/kg) was administered to 10 PMS patients and 10 healthy controls during the follicular and luteal phases of the menstrual cycle. We observed the following. m-CPP administration during the luteal phase resulted in an acute improvement of PMS symptoms; the plasma cortisol and ACTH responses to m-CPP were blunted in both menstrual cycle phases in PMS patients compared with controls. These data provide evidence for the acute efficacy of m-CPP in the treatment of PMS. Although there is additional evidence for dysregulation of either the hypothalamic-pituitary-adrenal axis or serotonin control of the hypothalamic-pituitary-adrenal axis in women with PMS, there is little evidence for luteal phase-specific serotonergic dysfunction. These findings, nonetheless, implicate the serotonin system as a modulating (not causal) factor in PMS.

Adult↗
PubMed1987

Behavioral effects of the pyrazoloquinoline CGS 9896: agonist and antagonist actions in squirrel monkeys.

The behavioral effects of 2-p-chlorophenylpyrazolo[4,3-c]quinolin-3(5H)-one (CGS 9896) were compared with those of lorazepam and zopiclone in squirrel monkeys. Two groups of monkeys were trained to respond under a fixed-interval schedule of food presentation. In one group, responding was suppressed (punished) by superimposing a fixed-ratio schedule of response-produced shock. Dose-effect curves were determined for all three drugs by administering cumulative doses i.v. during timeout periods that preceded sequential components of the fixed-interval schedule. Low and intermediate doses of CGS 9896 (0.03-3.0 mg/kg), lorazepam (0.03-0.3 mg/kg) or zopiclone (0.1-1.0 mg/kg) produced dose-related increases in the rates of both suppressed and nonsuppressed responding. The maximal increases in response rates produced by CGS 9896 were usually less than those produced by either lorazepam or zopiclone. Pretreatment with the benzodiazepine antagonist Ro 15-1788 antagonized the increases in suppressed and nonsuppressed response rates produced normally by intermediate doses of CGS 9896, lorazepam or zopiclone, suggesting that the rate-increasing effects of the three drugs are mediated similarly. CGS 9896 was studied additionally for antagonist activity by administering selected doses before lorazepam or zopiclone. Pretreatment with a high dose of CGS 9896 (5.0 mg/kg) antagonized the rate-increasing effects of both lorazepam and zopiclone, suggesting that CGS 9896 has antagonist effects in addition to its agonist effects at benzodiazepine recognition sites.

Animals↗
PubMed1991

The behavioral genetics of colony defense in honeybees: genetic variability for guarding behavior.

Guard honeybees stand at the entrance of colonies and facilitate the exclusion of nonnestmates from the colony. In this study, we examined the hypothesis that genetic variability among individuals in colonies might explain variability in guarding activity. To do this, we cross-fostered honey bees between colonies with high-defensive responses and colonies with low-defensive responses in alarm pheromone tests. Individuals from high-defensive colonies were more likely to guard in their own colonies (controls) than cross-fostered bees from low-defensive colonies. Cross-fostered high-defensive bees also were more like to guard in low-defense colonies. These results support the hypothesis that interindividual differences in guarding behavior are at least partially under genetic control. A positive correlation between number of guards and response to alarm pheromone demonstrates a link between behaviorally separated components of the overall defensive response.

Agonistic Behavior↗
PubMed1983

Influence of isolation and training on fighting in mice with olfactory bulb lesions.

Isolation-induced aggressive mice receiving total bilateral bulbectomy failed to fight after chronic training. Animals receiving sub-total olfactory bulbectomy were capable of being trained to attack but the latency to attack was increased. When mice were bulbectomized before being isolated they were incapable of attack regardless of training or completeness of the lesion. These results indicated that isolation influences aggressive behavior in bilaterally bulbectomized mice.

Aggression↗
PubMed1982

Effect of lithium upon desipramine enhanced shock-elicited fighting in rats.

Rats were tested for changes in shock-elicited fighting (SEF) following the chronic administration of saline (IP); lithium (Li+) (20 mEq./l tap water) + saline (IP); desipramine (DMI) (15 mg/kg, IP); and DMI + Li+ for 14 days. The repeated test trials indicated a significant decrease in SEF in Li+-saline group (p less than 0.05), a significant increase (p less than p.05) in the DMI group, but no difference in the DMI + Li+ group in comparison to saline controls. Combined treatment with DMI + Li+ significantly reduced (p less than 0.05) SEF in comprison to the DMI group. These results suggest that enhanced aggressivity resulting from chronic DMI administration and measured by SEF can be a useful behavioral model to study the action of lithium.

Aggression↗
PubMed1995

Hormonal and metabolic responses during psychosocial stimulation in aggressive and nonaggressive rats.

The physiological effects of a psychosocial threat (the mere presence of a potentially antagonist individual in the home cage) were studied in aggressive and nonaggressive rats. Aggressive animals spent a significantly longer time with the investigation of the opponent compared with the nonaggressive group. An increase in plasma epinephrine and corticosterone was noticed both in aggressive and nonaggressive animals. Ir beta-endorphin increased significantly only in nonfighters. Glycemia was slightly larger in nonaggressives, while lactaemia increased in both groups. The possibility is discussed that differences in psychosocial stress response may be involved in the regulation of behavior in a real encounter.

Adrenocorticotropic Hormone↗
PubMed1983

Effects of post-trial administration of naloxone and beta-endorphin on shock-induced fighting in rats.

To study the involvement of endogenous opioid peptides in the development of shock-induced fighting, naloxone (2 mg/kg) or beta-endorphin (10 micrograms/kg) was administered subcutaneously immediately after the session and during nine consecutive daily sessions to rats repeatedly exposed to electric shocks. beta-Endorphin blocked the development of shock-induced fighting while naloxone facilitated it but only when shock-induced fighting occurred at a low rate. The effects of beta-endorphin were time dependent since when beta-endorphin was injected 90 min after the shock session instead of immediately after, its impairing effect disappeared. In addition, naloxone blocked the impairment produced by beta-endorphin. Differential postsession treatment of each member of pairs of rats with naloxone and beta-endorphin resulted in a higher probability of rats treated with naloxone to be dominant over rats treated with beta-endorphin in the test situation. These results are discussed in relation with the possible involvement of endogenous opioids in the modulation of the physiological consequences of defensive behavioral responses to shock.

Aggression↗
PubMed2003

Predatory hunting and exposure to a live predator induce opposite patterns of Fos immunoreactivity in the PAG.

Considering the periaqueductal gray's (PAG) general roles in mediating motivational responses, in the present study, we compared the Fos expression pattern in the PAG induced by innate behaviors underlain by opposite motivational drivers, in rats, namely, insect predation and defensive behavior evoked by the confrontation with a live predator (a cat). Exposure to the predator was associated with a striking Fos expression in the PAG, where, at rostral levels, an intense Fos expression was found largely distributed in the dorsomedial and dorsolateral regions, whereas, at caudal levels, Fos-labeled cells tended to be mostly found in the lateral and ventrolateral columns, as well as in the dorsal raphe nucleus. Quite the opposite, insect predation was associated with increased Fos expression predominantly in the rostral two thirds of the lateral PAG, where the majority of the Fos-immunoreactive cells were found at the oculomotor nucleus levels. Remarkably, both exposure to the cat and insect predation upregulated Fos expression in the supraoculomotor region and the laterodorsal tegmental nucleus. Overall, the present results clearly suggest that the PAG activation pattern appears to reflect, at least partly, the animal's motivational status. It is well established that the PAG is critical for the expression of defensive responses, and, considering the present findings, it will be important to investigate how the PAG contributes to the expression of the predatory behavior, as well.

Aggression↗