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PubMed1987

Sodium valproate: effects on maternal behaviour in the mouse.

The behaviour of lactating mice in their home cages was examined by ethological procedures at 1, 7, 14 and 21 days postpartum. Early in lactation, maternal behaviour was more frequent in the light phase of the 24 hr cycle, whereas non-social activity occupied a greater amount of time during the dark phase. As the pups became older, maternal behaviour declined, and at 21 days the dams showed a marked increase of solitary immobility. Behavioural alterations produced by the administration of sodium valproate at 600 mg/l as drinking fluid during pregnancy and lactation (group SVP), and during lactation only, (group PN) were assessed. (Intake of drug amounted to 153 mg/kg during gestation and 186 mg/kg in lactation). Dams of group PN showed behavioural differences from controls in late lactation, pup nursing being prolonged at day 14 postpartum and the frequency of all categories of active behaviour, other than nursing and nestbuilding, was increased at day 21 postpartum in the dark phase of their daily cycle. There was not significant effect on categories of behaviour in dams of the SVP group. Overall, sodium valproate, at this dose, did not reduce maternal care.

Animals↗
PubMed1989

Kelatorphan, a potent enkephalinases inhibitor, and opioid receptor agonists DAGO and DTLET, differentially modulate self-stimulation behaviour depending on the site of administration.

Endogenous enkephalins have been found in the perikaryon of the mesolimbic dopaminergic ventral tegmental area and in axonal terminals in the nucleus accumbens. To examine whether endogenous opioid peptides may modulate this mesolimbic system, injections of dopamine receptor agonists and antagonist, the mu-opioid receptor agonists DAGO and morphine, the delta-opioid receptor agonist DTLET and kelatorphan, a new potent inhibitor of multiple enkephalin-degrading enzymes, were performed into the lateral ventricle and into the nucleus accumbens. Intracranial self-stimulation behaviour, obtained through electrodes chronically implanted into the medial forebrain bundle in the posterolateral hypothalamus of the rat, was used as behavioural paradigm. Injections of kelatorphan and DTLET into the lateral ventricle both induced an ICI 174,864-reversible increased self-stimulation behaviour, a similar increase was observed after injection of d-amphetamine, while morphine and DAGO reduced the rate of self-stimulation. In contrast, the administration of kelatorphan or dopamine receptor agonists into the nucleus accumbens reduced the rate of intracranial self-stimulation, while DTLET was without effect, when injected into the same structure. Finally, intra-accumbens injections of DAGO produced a similar behavioural profile to that produced by intraventricular injections of the drugs. Opioids may thus differentially affect intracranial self-stimulation behaviour, as a function of the neuroanatomical locus of administration. Furthermore, these results suggest that kelatorphan may increase self-stimulation behaviour through an action at delta-opioid receptor, while DAGO and morphine may reduce self-stimulation behaviour through an action at mu-opioid receptors.

Animals↗
PubMed1985

Studies into the dual effects of serotonergic pharmacological agents on female sexual behaviour in the rat: preliminary evidence that endogenous 5HT is stimulatory.

The potential stimulatory and inhibitory effects on female sexual behaviour of five 5HT antagonists and five agents that increase 5HT activity, were noted in ovariectomised rats primed with various steroid regimes such that they were either "receptive" (LQ greater than 50%) or "non-receptive" (LQ less than 50%). The 5HT antagonists cinanserin, mianserin, ketanserin and metergoline all inhibited behaviour in receptive rats. Methysergide and cinanserin stimulated behaviour in non-receptive rats. All the drugs which increased 5HTP activity, i.e., 5HTP, zimelidine, alaproclate, WY 26002 and quipazine stimulated sex behaviour in non-receptive rats. In rats that had been ovariectomised only, part of this effect was probably due to stimulation of adrenal progesterone, but a significant stimulatory effect could still be observed in ovariectomised-adrenalectomised rats. 5HT also had a significant inhibitory effect on receptive rats, and the other agonists showed a similar but non-significant tendency. In view of the fact that 4 out of 5 of the 5HT antagonists inhibited sexual behaviour, we hypothesise that 5HT has a stimulatory role in the control of female sexual behaviour. The possible mechanisms mediating the dual action of 5HTP on female sexual behaviour are discussed.

5-Hydroxytryptophan↗
PubMed1986

Different behavioural patterns induced by the dopamine agonist apomorphine analysed by multivariate statistics.

Exploratory behaviour was recorded in an automatic holeboard apparatus measuring activity, locomotion, rearing, hole exploration and corner restricted behaviour. Multivariate statistical methods were used to analyse the results. Low doses of the dopamine agonist apomorphine (0.01-0.1 mg/kg SC) dose-dependently reduced most variables measured, although the pattern of behaviour resembled that of normal animals. High doses of apomorphine (0.2-1.0 mg/kg SC) induced a qualitative change in the pattern of behaviour with a stereotyped locomotion and a reduced mean time of exploration of holes. The described methods for detection and statistical analysis of behaviour differentiates between the behavioural patterns induced by high and low doses of apomorphine and may be useful in finding and analysing patterns of drug induced behaviour related to various mechanisms of action.

Animals↗
PubMed1990

Behavioural actions of the serotonergic anxiolytic indorenate.

Several recent studies have shown that the 5-HT1A agonist indorenate possesses antianxiety properties. In the present study we report on other behavioural actions of this drug. Indorenate (31.6 mg/kg) induced flat body posture, forepaw treading and hind limb abduction, behavioural characteristics of the serotonin syndrome. After indorenate injection these same behaviours were observed in animals pretreated with p-chlorophenylalanine (400 mg/kg X 3 days), suggesting that the action of this compound is not mediated via serotonin release. The beta-5-HT1 blockers, (-) pindolol (2 mg/kg) or (-) alprenolol (5 mg/kg), did not prevent the actions of indorenate on the serotonin syndrome. Indorenate (10 mg/kg) stimulated the masculine sexual behaviour by reducing the number of intromissions preceding ejaculation. Higher doses (17.8 mg/kg) cause a complete inhibition of sexual behaviour. (-) Pindolol (2 mg/kg) or (-) alprenolol (5 mg/kg) did not antagonize the facilitatory actions of indorenate on male sexual behaviour. A high dose of indorenate (31.6 mg/kg) resulted in an impairment of the motor coordination as tested in a treadmill apparatus. These data reveal that indorenate possesses, in addition to its antianxiety effects, other behavioural characteristics that, however, appear at higher dose levels.

5-Methoxytryptamine↗
PubMed1991

Postsynaptic 5-HT1 receptors and offensive aggression in rats: a combined behavioural and autoradiographic study with eltoprazine.

The present study was designed to assess whether the antiaggressive effects of eltoprazine are mediated via presynaptic and/or postsynaptic 5-HT1 receptors. We describe the effects of central 5-HT depletion 1) on the behaviour of resident TMD-S3 rats in a territorial situation, 2) on the efficacy of eltoprazine to inhibit offensive aggression, and 3) on the 5-HT1A, 5-HT1B and 5-HT1C receptor binding in brains of rats previously used in behavioural studies. Male resident rats were given combined 5,7-dihydroxytryptamine (5,7-DHT) injections into the dorsal and median raphe nuclei. Two to four weeks after the lesions, rats were confronted with an intruder Wiser rat in their home cage for a 10-min period. The 5,7-DHT treatment resulted in a modest reduction of offensive behaviour, while having no effects on other social and nonsocial behaviours. Oral administration of eltoprazine (1 mg/kg) specifically reduced offensive aggression in both sham- and 5,7-DHT-lesioned animals, leaving social interest and exploration intact or even increasing it. A low dose (0.3 mg/kg) of eltoprazine did not affect the behavioural repertoire of sham-operated rats, whereas this dose significantly reduced offense behaviours in the 5,7-DHT-lesioned residents. Quantitative autoradiographic studies 5 weeks after 5,7-DHT treatment revealed a significant increase in radioligand binding to 5-HT1A, 5-HT1B and 5-HT1C sites in many brain regions studied, except for the raphe nuclei where [3H]8-OH-DPAT binding to 5-HT1A sites was markedly reduced. The concentrations of 5-HT and 5-HIAA in frontal cortex were reduced to approximately 10% of controls. The results indicate that serotonin has a stimulatory rather than an inhibitory influence on offensive aggressive behaviour. Central 5-HT depletion does not prevent the antiaggressive effects of eltoprazine, indicating a role for postsynaptic 5-HT1 receptors in the modulation of offensive aggression. The 5,7-DHT-induced overall upregulation of 5-HT1A, 5-HT1B and 5-HT1C binding sites suggests that these three receptor subtypes receive a tonic serotonergic influence. It is conceivable that this postsynaptic 5-HT1 receptor supersensitivity is reflected by the increased efficacy of eltoprazine to inhibit offensive aggression.

5,7-Dihydroxytryptamine↗
PubMed1996

Metergoline antagonizes fluoxetine-induced suppression of food intake but not changes in the behavioural satiety sequence.

In this study continuous monitoring was used to yield a true behavioural record. This allows a bidimensional account of drug effects on every unit of behaviour. Behavioural dimensions of duration (dur) and frequency (frq) measures were utilized to monitor the effects of an ED50 anorectic dose of fluoxetine (10 mg/kg i.p.) on the behavioural satiety sequence and the effect of a metergoline (1 mg/kg i.p.) challenge. Fluoxetine reduced food intake by 45% (p < 0.005). The local eating rate was also reduced (p < 0.001), demonstrating a marked slowing of eating behaviour. Eating behaviour was reduced (frq p < 0.05) as was grooming (frq p < 0.05) and activity. Resting was increased (dur p < 0.05) and temporally advanced. There was no gross disruption of behaviour and the profile was adjusted in a way consistent with the expression of satiety. Fluoxetine-induced changes were very similar to those produced by prefeeding. Metergoline antagonised fluoxetine's effect on intake and eating duration (dur p < 0.05). However, metergoline did not antagonise the effect of fluoxetine on the frequency of eating (frq p < 0.005), thus increasing the amount consumed per eating episode. Grooming (frq p < 0.005) and activity also remained reduced. At this dose fluoxetine-induced suppression of eating is serotonin dependent as it is reversed by metergoline. Fluoxetine-induced suppression of eating at this dose is consistent with the normal operation of satiety. Fluoxetine-induced slowing of behavior appears to be mediated by a separate mechanism.

Animals↗
PubMed1992

Drugs of abuse: behavioural principles, methods and terms.

Current understanding of drug abuse has been greatly influenced by the emphasis on drug-seeking behaviour as the common element. The three main attributes of drugs that maintain, direct and regulate drug-seeking behaviour are their positively reinforcing and discriminative and aversive stimulus properties. Each process may be analysed in terms of underlying behavioural and neural mechanisms that are mutually complementary and interactive. Environmental stimuli conditioned to the effects of the drugs also play a key role in eliciting and maintaining drug-seeking behaviour. Both the behavioural and the neural mechanisms are subject to modulating variables such as social, environmental and genetic factors, including the previous behavioural and pharmacological history of the individual. Thus, the behavioural approach to addiction does not preclude important roles for other factors, but rather seeks to integrate them into a comprehensive theoretical framework strongly linked to empirical data.

Animals↗
PubMed1994

The prefrontal cortex and variants of sequential behaviour indications of functional differentiation between subdivisions of the rat's prefrontal cortex.

In two separate experiments we addressed the involvement of the rat's prefrontal cortex in mediation of the sequential ordering of the "components of behaviour". In both experiments the animals were required to operate two different and spatially distant manipulanda sequentially. While in the first experiment a light cue signalled which response would at any moment be appropriate no sensory cues offered procedural guidance during the second experiment. Both experiments focused on postoperative retention performance. In the first experiment we studied the consequences of ablation of the dorsal anteromedial cortex, the total anteromedial cortex and the suprarhinal cortex as compared to a sham operated control group. In the second experiment we compared a sham operated group to a group subjected to ablation of the total anteromedial cortex. While the proficiency of task performance was evaluated on the basis of the number of reinforcements obtained and the percentage of bar presses to be reinforced, additional analysis of behaviour included registration of the individual behavioural components and the sequential orders in which these were observed. The major findings were: (1) lesions within the anteromedial, prefrontal cortex (especially if including the ventral part of this region) are associated with significantly impaired performance of both the presently investigated tasks. (2) The demonstrated association between the anteromedial cortex and the mediation of the sequential arrangement of behavioural components does not seem to be secondary to changes in neither quality nor frequency of any individual behavioural component. (3) In the first experiment--where a cue light signalled which response would at any point in time be adequate--lesions within all parts of the prefrontal cortex (the suprarhinal as well as the anteromedial cortex) were associated with overproduction of errors, which in the behavioural sequence analysis had been characterized as "type B". We tentatively interpret such errors as reflecting a failure to utilize the visual cue offered by the signal lamp. Since lesions within all parts of the prefrontal cortex seem to be associated with "cue utilization" failures while only lesions involving the anteromedial cortex are reflected in impaired sequential arrangement of behavioural components the present studies seem to reflect a certain degree of functional specialization within the prefrontal cortex of the rat.

Animals↗
PubMed1990

Promoting healthy behaviour: the importance of economic analysis in policy formulation for AIDS prevention.

Considerable attention has been paid in the literature to modification of high-risk behaviours as a means to control the spread of the Human Immunodeficiency Virus. The success of such policies will depend crucially on the underlying causal mechanisms of these high-risk behaviours. To date the application of economics to the problem of AIDS has tended to focus on estimating the economic burden of the condition and the resource consequences of clinical strategies for care. Yet as a behavioural science economics should provide a useful input into the policy process aimed at behaviour modification. In this paper we extend the application of economic analysis to the determinants of individual behaviour to identify (i) the implications of current policies for the incidence of high-risk behaviour and (ii) the wider determinants of behaviour warranting greater attention in the policy-making process.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The social definition of women's smoking behaviour.

The history of women's smoking behaviour is one of changing normative definitions. Recent trends have been explained in terms of the symbolic value of smoking, representing for women freedom and independence. This view is emphasised by advertising. However, other evidence suggests the continued existence of an older, more negative cultural stereotype. A two-part study of young women undergoing professional training for nursing and teaching throws some light on the way in which female smoking behaviour is currently socially interpreted. The first phase indicated that among the minority of parents who had expressed their attitudes towards their daughter's smoking in relation to sex-role norms, smoking was presented as unacceptable for women. More than half the sample perceived a negative cultural stereotype to be operating in contemporary society and two-thirds recognised its existence in the past. This stereotype presents smoking as a male behaviour and hence inappropriate for women. Women who do smoke are liable to be labelled as having unfeminine or degrading attributes. The stereotype operated more strongly in the general social background rather than in reference to personal relationships and hence its influence on contemporary behaviour is likely to be limited. It was rejected as out-dated or a male belief by some but nevertheless it represented the personal opinion of others. In terms of a more favourable definition the female smoker was perceived in terms of an elegant/sophisticated dimension and in relation to an extrovert personality. The view of sample members that the growing acceptability of women's smoking was related to social change indirectly supported the view that sees smoking as symbolic of independence. Those who saw smoking in neutral terms, i.e. as not having sex-role attributes, perceived smoking in this sense as normal social behaviour for men and women alike. The second phase suggested that smokers and non-smokers have divergent views about the image of the female smoker. The non-smoker's image was based on the older cultural stereotype ('unladylike'), whereas the smokers were more likely to take a view corresponding to the perspective that sees women's smoking as symbolic of social change and greater independence ('liberated'). The non-smokers had a clear and positive image of 'girls who don't smoke' ('feminine'), whereas for smokers the female non-smoker lacked a distinctive identity. The study thus suggests that traditional concepts of appropriate female behaviour continue to inhibit smoking among some women, whereas others perceive it as an aspect of independent behaviour.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

The health of adolescents: beliefs and behaviour.

Adolescence is a period of transition from childhood to adulthood in which interlocking changes in the body, mind and social relationship take place. Healthy development depends on both a propitious environment and the action of adolescents themselves. A stable family, peace, material conditions for physical health, and educational, social and vocational opportunities with a chance to make use of them before marriage, are necessary environment conditions. However, within this context the adolescent must experiment with new behaviours and relationships inevitably courting some risks. Adolescent health is especially linked to behaviour. If the environment is inadequate or dangerous and the adolescent lacks self-esteem, behaviours dangerous to health are more likely to occur. These include: precocious and unprotected sexual behaviour sometimes resulting in too early or unwanted pregnancy and sexually transmitted diseases; the use of tobacco, alcohol and other drugs; injuries arising accidentally from risk taking behaviours especially when combined with alcohol or drugs; intentional injury whether self-inflicted or inflicted by others; and poor eating and habits of hygiene leading to obesity, or emaciation, acne and poor teeth and gums. Adolescent behaviour is often governed by their beliefs about what others think. Two way communication in a trusting atmosphere will reduce myths and misinformation and encourage healthy behaviour. The promotion of health, the prevention of problems, and their treatment and rehabilitation when they arise can best be accomplished with the active co-operation of young people.

Adolescent↗
PubMed1990

Determinants of active self-care behaviour of insulin treated patients with diabetes: implications for diabetes education.

The most important aim of diabetes education is to alter the self-care behaviour of patients with diabetes. In order to change their behaviour its determinants must be known. The pretest of a multicentre evaluation study with 558 participating insulin treated patients with diabetes was analysed to test the usefulness of the attitude-behaviour theory of Fishbein & Ajzen in explaining and possibly changing diabetes related active self-care behaviour. The theory of Fishbein & Ajzen is based on the assumption that human behaviour is reasoned behaviour. The theory views a person's intention as the immediate determinant of action. Determinants of intention are attitude and social norm. The results showed that the attitude was the most important determinant of active self-care, while a sufficient level of knowledge and a low orientation on the powerful others health locus of control scale were prerequisites for a positive attitude. The influence of the social environment was detrimental; although people tried to motivate patients to active self-care, they could not provide any real help in performing this desired behaviour. According to the results of this study, diabetes education should first aim at improving the level of knowledge and the health locus of control of the patients and second, at a positive attitude to active self-care. It is necessary to educate the social environment to create a more supportive atmosphere for the patient with diabetes.

Adult↗
PubMed1995

Socio-cultural and behavioural aspects of mosquito-borne lymphatic filariasis in Thailand: a qualitative analysis.

This study examines the contribution of socio-cultural and behavioural factors in mosquito-borne lymphatic filariasis transmission in Southern Thailand. Research was conducted in Nakorn-srithamarat province, which is noted for having the nation's highest Brugia malayi filariasis morbidity rate. Factors examined include traditional knowledge and cultural beliefs concerning etiology, transmission and symptomatology; perceived susceptibility and severity: social stigma: social support in disease prevention and control; and behavioural risk factors and illness behaviours. Data were collected through a multi-method, predominantly qualitative-based approach, including rapid survey and mapping, group interviews, focus group discussions, indepth interviews, and participant observation. Results indicate that poor knowledge and lay, indigenous, traditional belief systems contribute to high risk behaviours, and inappropriate preventive, illness and treatment choice behaviours. Behavioural models for explaining filariasis risk, preventive, illness and treatment choice behaviours are presented. Finally, recommendations for more effective health education programmes are offered.

Adolescent↗
PubMed1996

Health lifestyle behaviour and socio-demographic characteristics. A study of Varna, Glasgow and Edinburgh.

In this paper a lifestyle perspective is taken to study the various influences on four health related behaviours, i.e. cigarette smoking, diet behaviour, alcohol use and exercise. Of interest is how these behaviours are distributed over four socio-demographic indicators, i.e. the respondents gender, educational level, employment status and age. As a third factor the respondent's city of residence, Varna in Bulgaria and Glasgow and Edinburgh in Scotland, is taken into consideration. Data collected by telephone from 268 respondents from Varna, 827 respondents from Glasgow and 275 respondents from Edinburgh are considered. Large differences in the prevalence of health behaviours are found, with respondents in Varna behaving least healthily and respondents in Edinburgh behaving most healthily, and this is also true at sub-group level. Alcohol use is the exception, and here the opposite relationship between health behaviour and city of residence is found. Females generally behave more healthily than males, however, this pattern is not consistent for all health behaviours. Better educated and employed respondents behave in a more healthy way compared with less well educated and unemployed respondents and this is true in all three cities, with the difference being particularly large in Scotland. An 'economic' and a 'self-care' explanation are put forward to explain the patterns observed but both explanations are found wanting. It is proposed that integrating various theoretical models is necessary to further develop our understanding of health lifestyle behaviour.

Adolescent↗
PubMed1987

Convulsant action of morphine, [D-Ala2, D-Leu5]-enkephalin and naloxone in the rat amygdala: electroencephalographic, morphological and behavioural sequelae.

Morphine hydrochloride (25-200 nmol), [D-Ala2, D-Leu5]enkephalin (10-200 nmol) and naloxone hydrochloride (100-1000 nmol) were injected unilaterally into the rat amygdala and the following electrographic, behavioural and neuropathological responses were studied. Microinjections of low doses of morphine (25-50 nmol) resulted in behavioural alterations characterized by staring, gustatory automatisms and wet shakes, whereas higher doses additionally produced motor limbic seizures and status epilepticus. The first changes in the electroencephalogram appeared in the amygdala immediately after the administration of morphine and rapidly spread to hippocampal and cortical areas. Electrographic alterations consisted of high voltage fast activity, spiking, bursts of polyspiking, electrographic seizures and periods of postictal depression. Neuropathological analysis of frontal forebrain sections by means of light microscopy revealed widespread, seizure-related damage confined to amygdala, olfactory cortex, thalamus, hippocampal formation, neocortex and substantia nigra. Pretreatment of animals with naloxone, 2-20 mg/kg s.c., as well as simultaneous microinjection of the non-convulsant dose of naloxone, 100 nmol, with morphine, 100 nmol, into the amygdala failed to block the development of convulsant activity and seizure-related brain damage produced by the opiate. In contrast, diazepam, 10 mg/kg i.p., when administered prior to the microinjection of morphine into the amygdala, abolished the epileptogenic effects of the drug. [D-Ala2, D-Leu5]Enkephalin, 10-200 nmol, elicited electrographic and behavioural responses similar to those seen after low doses of morphine, when administered into the amygdala. High voltage fast activity, single spikes, bursts of polyspiking, electrographic seizures and periods of postictal depression were seen in the electroencephalogram, but no behavioural signs of motor limbic seizures could be detected. The only behavioural correlates of epileptiform electrographic activity were wet shakes, myoclonic head twiches and gustatory automatisms. The examination of frontal forebrain sections from rats receiving [D-Ala2, D-Leu5]enkephalin revealed no morphological changes. Pretreatment of rats with either naloxone, 2 mg/kg, or diazepam, 10 mg/kg, blocked the development of behavioural and electrographic sequelae of the peptide. Naloxone, 100-1000 nmol, when microinjected into the amygdala, produced electrographic, behavioural and morphological alterations resembling those seen after high doses of morphine.(ABSTRACT TRUNCATED AT 400 WORDS)

Amygdala↗
PubMed1987

Selective effects of beta-endorphin infused into the hypothalamus, preoptic area and bed nucleus of the stria terminalis on the sexual and ingestive behaviour of male rats.

beta-Endorphin was infused bilaterally into the medial preoptic area-anterior hypothalamic continuum at doses of 5, 10 and 40 pmol each side. The highest dose selectively abolished mounting, intromitting and ejaculating in sexually experienced male rats paired with an oestrous female. Males infused with 40 pmol beta-endorphin still followed the female, investigated her anogenital region and other parts of her body, but made abortive attempts to mount. A dose of 5 pmol beta-endorphin had no effect, but 10 pmol proved partially effective. The same males, in other tests, were allowed to ingest a highly preferred, sweet, non-calorific solution (acesulfame-K) in the absence of a female. beta-Endorphin infusions (up to 40 pmol) into the same area of the hypothalamus had no effect on this behaviour. Control males allowed simultaneous access both to an oestrous female and to the sweet solution copulated normally but reduced their ingestive behaviour, despite there being sufficient time during tests for both to occur. beta-Endorphin (40 pmol) infused into the preoptic area-anterior hypothalamic continuum under these conditions suppressed sexual interaction, but ingestion of acesulfame-K increased to values observed when the female was absent. beta-Endorphin infused into neighbouring areas of the brain had different behavioural effects. Sexual behaviour was not inhibited, and ingestion of acesulfame-K was unaltered, when beta-endorphin was infused either into the bed nucleus of the stria terminalis or the rostral ventromedial hypothalamus. However, infusions of cholecystokinin-8 into the ventromedial hypothalamus suppressed acesulfame-K ingestion in most animals, showing that the cannulae were placed in an area regulating ingestive behaviour. The inhibition of sexual behaviour after preoptic area-anterior hypothalamic continuum infusions of beta-endorphin was prevented by either pretreating rats with 1 mg/kg naloxone intraperitoneally, or by infusing a putative delta opiate receptor blocker (0.5 pmols ICI 174864) into the preoptic area-anterior hypothalamic continuum 5 min prior to beta-endorphin treatment. ICI 174864 administered alone significantly increased mount rate and reduced the post-ejaculatory refractory period in copulating males. These experiments suggest that there is both neurochemical and neuroanatomical specificity relating beta-endorphin to sexual behaviour in the male rat.

Animals↗
PubMed1996

The olfactory bulb: a critical site of action for oxytocin in the induction of maternal behaviour in the rat.

Expanding on research showing that oxytocin originating in the hypothalamic paraventricular nucleus acts to decrease olfactory processing at the level of the olfactory bulb, we explored the importance of oxytocin acting on the olfactory bulb for the onset of maternal behaviour in Wistar rats. Experiment I was designed to test whether spontaneous maternal behaviour following natural delivery is blocked by bilateral infusions of a low dose (5 fmol) of the oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]ornithine-vasotocin into the olfactory bulb immediately after the delivery of the first pup and again just before a test for maternal behaviour. Intrabulbar infusions of the antagonist markedly delayed the occurrence of all components (retrieval, licking, nest building, crouching) of maternal behaviour, whereas intracerebroventricular infusions of the antagonist were without effect on any component as compared with intrabulbar infusions of saline. Experiment 2 was undertaken to determine whether infusions of oxytocin into the bulb induce a rapid onset of maternal behaviour in virgin rats. Forty-eight hours before pup presentation virgins were ovariectomized and treated with oestradiol benzoate. Immediately before pup presentation a low dose (20 pmol) of oxytocin or saline was infused bilaterally into the bulb or lateral ventricle. Intrabulbar infusions of oxytocin induced full maternal behaviour in half of the animals tested within 2 h of pup exposure, in contrast to the ineffectiveness of intracerebroventricular infusions of oxytocin and intrabulbar infusions of saline. These results suggest that the olfactory bulb is a critical site where oxytocin acts to induce a rapid onset of maternal behaviour.

Animals↗