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"Abnormal" illness behaviour in chronic fatigue syndrome and multiple sclerosis.

OBJECTIVE: To investigate the presence of abnormal illness behaviour in patients with a diagnosis of chronic fatigue syndrome. DESIGN: A cross sectional descriptive study using the illness behaviour questionnaire to compare illness behaviour scores and illness behaviour profiles of patients with chronic fatigue syndrome and patients with multiple sclerosis. SETTING: A multidisciplinary fatigue clinic and a teaching hospital neurology outpatient clinic. SUBJECTS: 98 patients satisfying the Oxford criteria for chronic fatigue syndrome and 78 patients with a diagnosis of multiple sclerosis. MAIN OUTCOME MEASURE: Responses to the 62 item illness behaviour questionnaire. RESULTS: 90 (92%) patients in the chronic fatigue syndrome group and 70 (90%) in the multiple sclerosis group completed the illness behaviour questionnaire. Both groups had significantly high scores on the general hypochondriasis and disease conviction subscales and significantly low scores on the psychological versus somatic concern subscale, as measured in relation to normative data. There were, however, no significant differences in the subscale scores between the two groups and the two groups had identical illness behaviour profiles. CONCLUSION: Scores on the illness behaviour questionnaire cannot be taken as evidence that chronic fatigue syndrome is a variety of abnormal illness behaviour, because the same profile occurs in multiple sclerosis. Neither can they be taken as evidence that chronic fatigue and multiple sclerosis share an aetiology. More needs to be known about the origins of illness beliefs in chronic fatigue syndrome, especially as they are important in determining outcome.

Adult↗

Influence of material and behavioural factors on occupational class differences in health.

OBJECTIVE: To examine material and behavioural factors as explanations for occupational class differences in health, while taking into account the interrelations between these two groups of factors. METHODS: Data from cross sectional surveys among middle aged women and men employed by the City of Helsinki (n = 6062, response rate 68%) were used. The contribution of four material and seven behavioural factors to occupational class differences in self rated health was examined by logistic regression techniques. After examining the contribution of each material and behavioural factor individually these were combined into two groups, whose independent and shared effects on occupational class differences in health were examined. RESULTS: In women, each material factor reduced the association between occupational class and health, while only financial difficulties and financial satisfaction were statistically significant in men. Smoking, dietary habits, and relative body weight were the strongest behavioural factors explaining the association in both women and men. When grouped, both material and behavioural factors explained a large part of occupational class differences in health. The direct effect of material factors was larger than their effect through behavioural factors, and the effect of behavioural factors depending on material factors was about half of their independent effect. CONCLUSIONS: Material and behavioural factors explained more than a half of occupational class differences in self rated health among women and one third among men. The effects of material and behavioural factors were mostly independent of each other, although some part of their contribution was shared, especially in women.

Cross-Sectional Studies↗

Dietary behaviour and health in Northern Ireland: an exploration of biochemical and haematological associations.

STUDY OBJECTIVE: The aim was to determine the relationships between dietary behaviour and biochemical and haematological measures. DESIGN: This was a cross sectional population study. SETTING: The study took place in the general community within Northern Ireland. SUBJECTS: 522 randomly selected adults aged 18-64 years took part (65% of the eligible sample). MEASUREMENTS AND MAIN RESULTS: Four dietary behaviours were identified using principal components analysis from 7 d weighed dietary records described in terms of mean intake of 41 food groups. Haematological and biochemical analyses were carried out on non-fasting blood samples. Social, personal, and lifestyle information was ascertained through interviewer administered questionnaires. Partial correlations controlled for age and smoking behaviour were calculated. There were significant negative associations between iron status measures and the "traditional" behaviour, while the "meat and two veg" behaviour showed positive associations. There were positive associations between the "cosmopolitan" and "convenience" behaviours and folate status in women. White cell count and platelet levels in women were negatively associated with the "traditional" and "cosmopolitan" behaviours. Total cholesterol levels showed significant negative associations with the "cosmopolitan" behaviour in women and HDL cholesterol levels were positively associated with the "cosmopolitan", "convenience" and "meat and two veg" behaviours. CONCLUSIONS: Through a multivariate approach to dietary assessment it is possible to identify food combinations that cluster and interact to influence biochemical and haematological indices of health status.

Adolescent↗

Health behaviours explain part of the differences in self reported health associated with partner/marital status in The Netherlands.

STUDY OBJECTIVE: To describe the differences in health behaviours in disparate marital status groups and to estimate the extent to which these can explain differences in health associated with marital status. DESIGN: Baseline data of a prospective cohort study were used. Directly age standardised percentages of each marital group that engaged in each of the following behaviours--smoking, alcohol consumption, coffee consumption, breakfast, leisure exercise, and body mass index--were computed. Multiple logistic regression models were fitted to estimate the health differences associated with marital status with and without control for differences in health behaviours. SETTING: The population of the city of Eindhoven and surrounding municipalities (mixed urban-rural area) in The Netherlands in March 1991. PARTICIPANTS: There were 16,311 men and women, aged 25-74 years, and of Dutch nationality. MAIN RESULTS: There were differences in relation to marital status for each health behaviour. Married people were more likely to practise positive health behaviours (such as exercise and eating breakfast) and less likely to engage in negative ones (such as smoking or drinking heavily) than the other groups. Control for all six health behaviours could explain an average of 20-36% of the differences in perceived and general health and subjective health complaints. CONCLUSIONS: Differences in health behaviours explained a considerable amount, but not all, of the health differences related to marital status. Longitudinal data are necessary to confirm these findings; to determine whether the differences in health behaviours related to marital status are caused by selection effects or social causation effects; and to learn how social control, social support, and stress inter-relate to reinforce negative or to maintain positive health behaviours.

Adult↗

A study of stereotypic behaviours in Alzheimer's disease and frontal and temporal variant frontotemporal dementia.

OBJECTIVE: To document the prevalence and pattern of stereotypic behaviour in patients with Alzheimer's dementia and frontal and temporal variants of frontotemporal dementia. Secondly, to examine the relationship between stereotypic and other neuropsychiatric behaviours. METHODS: Patients with the following were studied; Alzheimer's disease (n=28), frontal variant frontotemporal dementia (fvFTD, n=18), and semantic dementia-the temporal lobe variant of FTD (n=13). All patients were assessed using the Neuropsychiatric Inventory (NPI), the Mini-Mental State Examination, Addenbrooke's Cognitive Examination, and the Clinical Dementia Rating scale. Patients were also rated on the newly devised Stereotypic and Ritualistic Behaviour (SRB) subscale, which was designed as an addendum to the NPI. RESULTS: There was no significant difference across diagnostic groups in terms of age, sex, or severity of cognitive deficits. The overall NPI was significantly higher in patients with fvFTD compared with the other two groups, but fvFTD and semantic dementia showed a similar, and significantly increased, prevalence of stereotypic behaviours on the SRB subscale. Within the FTD group as a whole these behaviours were more likely to be complex, whereas in Alzheimer's disease, when present, such behaviours tended to be more simple stereotypies or stimulus bound repetitive behaviours. Stereotypic behaviours were not correlated with either disease severity or the extent of cognitive impairment in the fvFTD group, but were in the other two diagnostic groups. CONCLUSION: Complex stereotypic behaviours are a core feature of the dementing syndrome in FTD and may reflect early and specific deficits in orbitofrontal circuitry and basal ganglia involvement.

Aged↗

Sexually inappropriate behaviour in demented elderly people.

AIM: To determine the prevalence, aetiology, and treatment profile of abnormal sexual behaviour in subjects with dementia in psychogeriatric practices. METHODS: A retrospective cross sectional study was conducted in a long term care psychiatry consultation service, community based geriatric psychiatry service, and an inpatient dementia behavioural unit in Edmonton, Canada. RESULTS: Forty one subjects (1.8%) had sexually inappropriate behaviour. Of those cognitively impaired subjects with sexually inappropriate behaviour, 20 (48.8%) were living in nursing homes and the rest, 21 (51.2%) in the community. Of these subjects, 53.7% had vascular dementia, 22% had Alzheimer's, and 9.8% had mild cognitive impairment. History of alcohol misuse and psychosis were reported in 14.6% and 9.8% of subjects respectively. Twenty seven (65.7%) had verbally inappropriate behaviour and 36 (87.8%) had physically inappropriate behaviour. In this study, verbally inappropriate behaviour was more commonly seen in the community sample (81%) than in the nursing home sample (50%) (p = 0.04). Behavioural treatment was also more commonly seen in the community sample (81%) than in the nursing home sample (45%) (p = 0.01). CONCLUSION: In this study sexually inappropriate behaviour was seen in all stages of dementia, more commonly associated with subjects of vascular aetiology, and is as commonly seen in community dwelling subjects with dementia as in nursing home subjects.

Aged↗

Sexually transmitted disease among married Zambian women: the role of male and female sexual behaviour in prevention and management.

OBJECTIVES: Few studies have evaluated the relation between male and female sexual behaviour and STD among married African women. The objectives of this study were to identify male and female sexual behaviour associated with female STD, and to explore whether incorporating male and female sexual behaviour and male symptoms can improve algorithms for STD management in married African women. METHODS: 99 married couples with one symptomatic member (58 males, 41 females) attending an STD clinic in Lusaka, Zambia were interviewed separately about sexual and contraceptive behaviour, and had physical examinations. Diagnostic tests for Neisseria gonorrhoeae (GC), Trichomonas vaginalis (TV), and HIV were performed. Bivariate and multivariate odds ratios for the association between sexual behaviour and STD were calculated. Predictive algorithms based on current Zambian guidelines for management of STD in women were created. RESULTS: Among women at baseline, 10% were positive for GC, 14% for TV, 52% for HIV. Female alcohol use before sex, a male's paying for sex, and a couple's having sex unprotected by condoms or spermicides were associated with female STD. Incorporation of these behaviours along with symptoms of urethral discharge and dysuria among husbands increased the predictive ability of algorithms for management of STD in women. CONCLUSIONS: The addition of male and female sexual behaviour and male STD symptoms to diagnostic algorithms for female STD should be explored in other settings. Both husbands' and wives' behaviour independently predict STD in these women; risk reduction programmes should target both men's and women's sexual behaviour.

Adult↗

Psychosocial predictors of HIV/STI risk behaviours in a sample of homosexual men.

OBJECTIVES: To determine the prevalence of STI/HIV risk behaviours in a sample of homosexual men and investigate the psychosocial and cognitive variables associated with these behaviours. METHOD: A sample of 123 users of a homosexual men's sexual health clinic completed a questionnaire which included demographic information, psychometric measures, history of sexual risk behaviour, and history of non-consensual sex (NCS). RESULTS: High rates of sexual risk were found in this sample behaviour (36% of men had risky sex in the previous month) despite using a narrower definition than other recent studies. Comparable rates of non-consensual sex were found in this sample (26% of the sample had experienced NCS); however, this variable was not directly linked to increased risk behaviour. Depression and cognitions associated with controllability or predictability of risk were associated with increased HIV/STI risk behaviour. CONCLUSIONS: Clinical measures of depression are associated with risk behaviour in this sample as are cognitions about the uncontrollability of risk and reducing chances of exposure to HIV by insertive sexual practices and fidelity. Demographic variables, a history of non-consensual sex and depression are not predictors of risk behaviour when sexual risk cognitions are used to predict unsafe sexual practices indicating that cognitions are foremost in driving risk behaviours, demographic variables, and the NCS history of the subject. Given the considerable costs of providing medical care to patients with HIV it is likely that even modest reductions in rates of HIV infection through proactive psychological interventions to modify erroneous cognitions will prove highly cost effective.

Adult↗

Inhibition of constitutive nitric oxide production increases the severity of lipopolysaccharide-induced sickness behaviour: a role for TNF-alpha.

Administration of bacterial lipopolysaccharide (LPS) to rodents induces hypophagia, body weight loss and hypolocomotion, a constellation of symptoms collectively referred to as 'sickness behaviour'. We examined the role of the gaseous transmitter nitric oxide (NO) in mediating LPS-induced sickness behaviour in rats. Treatment with the non-selective NO synthase (NOS) inhibitor N(G)-nitro-L-arginine (L-NA) (20 mg/kg; i.p.) increased the severity of LPS-induced sickness behaviour in rats, suggesting that endogenous NO does not act as a mediator of LPS-induced sickness behaviour, but may rather have a protective role, acting in an inhibitory feedback manner to limit LPS-induced sickness. To evaluate the role of the different NOS isoforms in this response, we examined the effect of the neuronal NOS inhibitor, 7-nitroindazole (7-NI; 25 and 50 mg/kg; i.p.), and the inducible NOS inhibitor, aminoguanidine (AGN; 50 and 100 mg/kg; i.p.). Neither 7-NI nor AGN significantly altered LPS-induced sickness behaviour. Therefore, it is likely that the endothelial isoform of NOS mediates the effect of L-NA on LPS-induced sickness behaviour. As pro-inflammatory cytokines are mediators of LPS-induced sickness behaviour, we examined the effect of L-NA (20 mg/kg; i.p.) on LPS-induced interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF)-alpha production. L-NA increased LPS-induced TNF-alpha without significantly altering IL-1beta or IL-6 production. Moreover, pre-treatment with the TNF-alpha inhibitor pentoxyfilline (25 mg/kg; i.p.) largely reversed the augmenting effect of L-NA on LPS-induced sickness behaviour, suggesting that the ability of L-NA to increase TNF-alpha production underpinned its ability to increase the severity of sickness. In conclusion, L-NA increases the severity of LPS-induced sickness behaviour, most likely by blocking the tonic inhibitory action of constitutively produced NO on TNF-alpha production.

Animals↗

Comparative analyses of age- and sex-specific patterns of vocal behaviour in four species of Old World monkeys.

Sound recordings and behavioural data were collected from four primate species of two genera (Macaca, Presbytis). Comparative analyses of structural and behavioural aspects of vocal communication revealed a high degree of intrageneric similarity but striking intergeneric differences. In the two macaque species (Macaca silenus, Macaca radiata), males and females shared the major part of the repertoire. In contrast, in the two langurs (Presbytis johnii, Presbytis entellus), many calls were exclusive to adult males. Striking differences between both species groups occurred with respect to age-specific patterns of vocal behaviour. The diversity of vocal behaviour was assessed from the number of different calls used and the proportion of each call in relation to total vocal output for a given age/sex class. In Macaca, diversity decreases with the age of the vocalizer, whereas in Presbytis the age of the vocalizer and the diversity of vocal behaviour are positively correlated. A comparison of the data of the two genera does not suggest any causal relationship between group composition (e.g. multi-male vs. one-male group) and communication system. Within each genus, interspecific differences in vocal behaviour can be explained by differences in social behaviour (e.g. group cohesion, intergroup relation, mating behaviour) and functional disparities. Possible factors responsible for the pronounced intergeneric differences in vocal behaviour between Macaca and Presbytis are discussed.

Aging↗

Stress and depression in family carers following traumatic brain injury: the influence of beliefs about difficult behaviours.

OBJECTIVE: Difficult behaviours are significant contributors to the distress experienced by carers of people with a traumatic brain injury. This study investigated whether the beliefs carers hold about such behaviours also contribute to the distress. DESIGN: Questionnaire survey. PARTICIPANTS: Forty family carers recruited from Headway, a traumatic brain injury support organization. MAIN MEASURES: Zung's Self-Rating Depression Scale, Perceived Stress Scale, Social Support Questionnaire, a measure of the severity of difficult behaviours shown by the person cared for and two measures of carer beliefs about the behaviour (including the Controlling Beliefs Scale). RESULTS: Higher depression and stress scores were associated with more severe behaviours and less social support. Carer belief in their own ability to control the behaviours was associated with less stress. Belief that the behaviour was under the control of the person with traumatic brain injury and/or was motivated by hostile intentions was associated with more depression but less stress. Taken together, severity of behaviour and social support accounted for about 19% of the variance in both depression and stress scores. Carer beliefs accounted for another 5% of the depression scores, and another 11% of the stress scores. CONCLUSIONS: The results were consistent with the idea that carer beliefs about difficult behaviour contribute to carer distress, but longitudinal and treatment studies are needed to establish causality.

Adult↗

Social, demographic, and clinical factors related to disruptive behaviour in hospital.

OBJECTIVE: This study addresses 2 issues: first, whether the diagnosis of borderline personality disorder (BPD) or borderline traits differentiates adult patients who demonstrate disruptive behaviour during hospitalization from those patients who do not; and second, whether other clinical variables can be assessed during the emergency visit to differentiate patients who are likely to show disruptive behaviour in hospital from those who are not. METHOD: We completed a case-control, chart-based, retrospective analysis of patients consecutively admitted to an inpatient psychiatric service. We assembled 44 subjects who demonstrated evidence of disruptive behaviour during inpatient hospitalization. These subjects were matched with 61 control subjects admitted during the same time period. Potential participants were excluded if they had a diagnosis of schizophrenia, psychotic disorders, delirium, or dementia or if they had a diagnosis receiving a psychotic specifier. RESULTS: Univariate analyses revealed that patients with disruptive behaviour were significantly more likely to have been diagnosed with BPD or borderline traits than the comparison group (32.6% vs 13.4%; chi2 = 4.45, df 1; P < 0.05). According to stepwise logistic regression analysis, 4 variables significantly contributed to the final model (R2 = 0.37, P < 0.001) predicting disruptive behaviours with the following odds ratios (ORs): Axis III infectious diseases (OR 7.63; 95% CI, 1.41 to 41.67), Axis IV housing problems (OR 3.58; 95% CI, 1.21 to 10.64), history of suicidal behaviours (OR 3.46; 95% CI, 1.24 to 9.71), and problems with primary supports (OR 0.12; 95% CI, 0.03 to 0.46). This last variable was related to a reduced risk of disruptive behaviours in hospital. CONCLUSIONS: Patients at risk for disruptive behaviour during psychiatric hospitalization are characterized by a history of suicidal or impulsive-aggressive behaviour and social disadvantage.

Adult↗

Optomotor behaviour in Xenopus laevis tadpoles as a measure of the effect of gravity on visual and vestibular neural integration.

The ability of aquatic vertebrates to maintain their position requires integration of visual and vestibular sensory information. To understand better how aquatic animals integrate such information, we measured the optomotor behaviour of Xenopus laevis tadpoles raised in growth chambers in microgravity (< 10(-3)g), normal gravity (1 g), hypergravity (3 g) and on a slowly rotating clinostat (simulated microgravity). The goal of this research was to determine how development in an altered gravitational force field affects the visual- and vestibular-dependent behaviour of tadpoles. This research represents the first time that the optomotor behaviour of an organism raised from fertilization in microgravity has been tested. Significant differences were observed in the optomotor behaviour among the four gravity treatments. When first exposed to normal gravity, the microgravity-raised tadpoles exhibited the strongest (or most positive) optomotor behaviour, while the 3 g centrifuge tadpoles showed no optomotor response. Some abnormal behaviours (such as erratic swimming, lying motionless and abnormal swimming posture) were observed in the tadpoles raised in altered gravity on the initial day of testing. One day later, the tadpoles raised in hypergravity did not differ significantly in their optomotor behaviour from control tadpoles raised in normal gravity. However, tadpoles raised in microgravity still displayed an exaggerated optomotor response. One week after the tadpoles had been introduced to normal gravity, there was no longer a significant difference in optomotor behaviour among the different gravity treatments. This convergence of optomotor behaviour by tadpoles from the different treatment reflects the acclimation of their vestibular systems to normal gravity.

Animals↗

The role of learning to read in the development of problem behaviour: a cross-lagged longitudinal study.

BACKGROUND: This study investigates the posited relationship between learning to read, and internalizing and externalizing problem behaviours, during the transition from preschool to primary school. METHODS: A total of 196 (104 boys, 92 girls) children participating in the Jyväskylä Entrance into Primary School (JEPS) study were followed up six times during their transition from preschool to primary school. At each measurement, the children's reading performance was tested. Moreover, their internalizing and externalizing problem behaviour was examined by means of structured interviews. RESULTS: The results showed that problems in reading acquisition predicted an increase in internalizing problem behaviour during the preschool year and first grade, whereas during the second grade they were associated with an increase in subsequent externalizing problem behaviour. Moreover, from preschool to the beginning of the primary school internalizing problem behaviour predicted subsequent externalizing problem behaviour. Later on during the first and the second primary school years, it was externalizing problem behaviour that predicted an increase in internalizing problem behaviour. CONCLUSIONS: The results of this study suggested that difficulties in learning to read, and internalizing and externalizing problem behaviours are developmentally linked in a cumulative manner.

Child↗

Evidence that the type of person affects the strength of the perceived behavioural control-intention relationship.

This study examined the role of person type in explaining the relationship between perceived behavioural control and behavioural intentions. Participants (N = 187) completed measures of the theory of planned behaviour (Ajzen, 1991) variables regarding 30 behaviours. Within-participants analyses demonstrated that intentions were more strongly predicted by perceived behavioural control (PBC) than a combination of attitudes and subjective norms among a minority of the sample. When these 'PBC controlled' participants were considered separately, the effects for perceived behavioural control obtained in previous between-participants analyses were augmented. Conversely, when these participants were excluded from the sample, the effects of perceived behavioural control were reduced. PBC control was also modestly associated with dispositional measures of perceived controllability. Overall, the findings indicate that the strength of the perceived behavioural control-intention relationship depends not only on the type of behaviour but also on the type of person.

Humans↗

Augmenting the theory of planned behaviour with the prototype/willingness model: predictive validity of actor versus abstainer prototypes for adolescents' health-protective and health-risk intentions.

OBJECTIVES: The present research tested: (a) whether prototype perceptions and descriptive norms from the prototype/willingness model (PWM; Gibbons, Gerrard, Blanton, & Russell, 1998) enhance the prediction of adolescents' intentions to engage in health-protective and health-risk behaviours after variables from the theory of planned behaviour (TPB; Ajzen, 1991) and past behaviour have been taken into account and (b) whether images of the type of person who engages in a health behaviour (actor prototypes) and images of the type of person who does not engage in a health behaviour (abstainer prototypes) have equivalent predictive validity. DESIGN: An experimental design with a single between participants factor (actor versus abstainer prototype) was employed. METHOD: Participants in this study were 247 school pupils who completed measures of TPB variables, PWM variables and past behaviour in relation to three health-protective and three health-risk behaviours. RESULTS: Findings indicated that PWM variables accounted for a significant proportion of the variance in behavioural intentions after TPB variables and past behaviour had been taken into account (Mean deltaR2=.05). Perceived similarity to prototypes was the most consistent additional predictor of intention. Actor and abstainer prototypes exhibited equivalent predictive validity. CONCLUSIONS: The present research suggests that variables from the PWM, especially prototype similarity, enhance the predictive validity of the TPB. The findings also provide new evidence that acquiring the characteristics of both health and risk images may be goals among adolescents and suggest that both healthy and risky prototypes constitute useful cognitive targets for interventions.

Adolescent↗

Inhibition of sexual behaviour in lactating rats.

Treatment with oestradiol benzoate (OB; 2-250 micrograms) and progesterone (0.5-25 mg) failed to induce sexual behaviour in lactating rats 6 days after parturition. Removal of pups permitted the induction of sexual behaviour by OB and progesterone and the inhibitory effect of the presence of pups was proportional to the number present. Ovariectomy of lactating rats or reduction of serum prolactin levels in intact lactating rats by daily treatment with the dopamine receptor agonist bromocriptine (0.5 mg/day) permitted the induction of sexual behaviour despite the presence of suckling pups. Removal of pups from lactating rats and subsequent maintenance of high prolactin levels by daily treatment with the dopamine receptor antagonist domperidone (2.5 mg/day) maintained the state of refractoriness to the behavioural effects of OB and progesterone provided that the ovaries remained in situ. Inhibition of sexual behaviour in lactating rats could be maintained after ovariectomy by implantation of progesterone-filled, but not androgen-filled implants at the time of ovariectomy. Removal of the pups or reduction of prolactin levels by bromocriptine treatment permitted the induction of sexual behaviour by OB in ovariectomized progesterone-implanted lactating rats. Inhibition of the behaviour in ovariectomized progesterone-implanted lactating rats could be maintained after pup removal by daily domperidone treatment. Continuously raised serum progesterone or prolactin levels have no effect on the induction of sexual behaviour in female rats but the present data suggest that during lactation progesterone and prolactin act in synergy to inhibit the behaviour.

Animals↗

Effects of hyperprolactinaemia on male sexual behaviour in the golden hamster and mouse.

In the male rat, hyperprolactinaemia is associated with significant reductions in plasma LH and FSH levels and in several measures of copulatory behaviour. In contrast to this situation, experimental induction of hyperprolactinaemia in male mice and hamsters is associated with an increase in plasma gonadotrophin levels. It was therefore of interest to determine the effects of hyperprolactinaemia on the copulatory behaviour of these animals. Hyperprolactinaemia was induced by transplantation of pituitaries from adult females and sexual behaviour was tested in the presence of ovariectomized, oestrogen- and progesterone-treated females. Because hyperprolactinaemia increases plasma testosterone levels in intact male hamsters, the animals were castrated and implanted with testosterone-filled silicone elastomer capsules before induction of hyperprolactinaemia. In mice of two inbred strains, DBA/2J and C57BL/6Bg, hyperprolactinaemia appeared to stimulate male sexual behaviour as shown by a significant increase in the proportion of animals mating (C57BL/6) and a significant decrease in mount (DBA/2J) and intromission (C57BL/6Bg and DBA/2J) latencies. Similarly, hyperprolactinaemia did not suppress male copulatory behaviour in the hamster. In contrast, in two experiments in which the animals were tested three times for sexual behaviour, mount or intromission latencies were significantly reduced in pituitary-grafted, as compared with sham-operated males, in the first of the tests. Thus, in the mouse and the golden hamster, experimentally induced chronic hyperprolactinaemia stimulates both gonadotrophin release and male copulatory behaviour. These observations, together with the association of suppressive effects of hyperprolactinaemia on plasma LH and FSH levels and on sexual behaviour in the male rat, suggest the possible existence of a common mechanism underlying both endocrine and behavioural effects of hyperprolactinaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗