Effects of intrapartum oxytocin administration and epidural analgesia on the concentration of plasma oxytocin and prolactin, in response to suckling during the second day postpartum.

BACKGROUND: Oxytocin and prolactin stimulate milk ejection and milk production during breastfeeding. The aim of the present study was to make a detailed analysis of maternal release of oxytocin and prolactin in response to breastfeeding during the second day postpartum in mothers who had received oxytocin either intravenously for stimulation of labor or intramuscularly for prevention of postpartum hemorrhage and/or epidural analgesia or those who had received no such treatment in connection with birth. METHODS: In a descriptive comparative study plasma oxytocin and prolactin concentrations were measured in response to suckling during the second day postpartum in women who had received intravenous intrapartum oxytocin (n = 8), intramuscular postpartum oxytocin (n = 13), or epidural analgesia, either with (n = 14) or without (n = 6) intrapartum oxytocin infusion, and women who received none of these interventions (n = 20). Hormone levels were analyzed by enzyme immunoassay. RESULTS: All mothers showed a pulsatile oxytocin pattern during the first 10 minutes of breastfeeding. Women who had received epidural analgesia with oxytocin infusion had the lowest endogenous median oxytocin levels. The more oxytocin infusion the mothers had received during labor, the lower their endogenous oxytocin levels were during a breastfeeding during the second day postpartum. A significant rise of prolactin was observed after 20 minutes in all women, but after 10 minutes in mothers having received oxytocin infusion during labor. In all women, oxytocin variability and the rise of prolactin levels between 0 and 20 minutes correlated significantly with median oxytocin and prolactin levels. CONCLUSION: Oxytocin, released in a pulsatile way, and prolactin were released by breastfeeding during the second day postpartum. Oxytocin infusion decreased endogenous oxytocin levels dose-dependently. Furthermore, oxytocin infusion facilitated the release of prolactin. Epidural analgesia in combination with oxytocin infusion influenced endogenous oxytocin levels negatively.

Influence of oxytocin or epidural analgesia on personality profile in breastfeeding women: a comparative study.

Women undergo physiological and psychological changes during pregnancy, labor and lactation. The psychological adaptations can be affective, cognitive and behavioral and can be measured by dimensional personality instruments. This study aims to compare (1) the personality profile in mothers after birth with a normative group of non-lactating women and to examine (2) whether the personality profile differs 2 days, 2 months and 6 months after birth between mothers who have been exposed to epidural anesthesia, oxytocin administration or neither. Sixty-nine primiparae were assigned to four groups: mothers having received oxytocin infusion during labor (OT iv group, n = 9), mothers having received epidural analgesia with/without oxytocin infusion (EDA group, n = 23), mothers having received 10 iU oxytocin intramuscularly after birth (OT im group, n = 15) and mothers having received none of these treatments (unmedicated group, n = 22). At 2 days and 2 and 6 months postpartum mothers completed the Karolinska Scales of Personality (KSP). The unmedicated, the OT iv- and OT im groups scored significantly lower on anxiety and aggression related scales and higher on the socialization subscale during the entire observation period when compared with a normative group. These differences were not observed in the EDA group 2 days postpartum. At 2 and 6 months postpartum, the scores of the EDA group had changed significantly and were almost similar to the KSP scores of the other groups. ANCOVA analysis revealed that OT infusion, over and above the effects of EDA, was associated with decreased levels of several anxiety and aggression subscales. We conclude that women who received exogenous oxytocin during labor show similar positive personality traits during breastfeeding such as reduction in anxiety and aggression and increasing socialization, including maternal behavior, that have previously been ascribed to endogenous oxytocin. More importantly, these effects were not seen at 2 days postpartum in women who received epidural anesthesia during labor.

Short- and long-term decrease of blood pressure in women during breastfeeding.

BACKGROUND AND AIMS: The benefits of breastfeeding for infants are well known. Recently data have started to emerge showing that breastfeeding may also induce positive effects in the mother. This study aimed to investigate the pattern of maternal blood pressure before, during, and after a breastfeed 2 days postpartum. Additionally, blood pressure during the following 25-week breastfeeding period was investigated. METHODS: Sixty-six primiparae with normal deliveries were consecutively recruited. Blood pressure was measured at -5, 10, 30, and 60 minutes in connection with a morning breastfeed. Thirty-three women continued to measure blood pressure before and after breastfeeding for 25 weeks. RESULTS: Blood pressure fell significantly in response to breastfeeding 2 days after birth. The fall in systolic and diastolic blood pressure amounted to 8.8 (SD = 11.00) and 7.7 (SD = 9.3) mm Hg, respectively. During the 25-week follow-up period a significant fall of basal blood pressure (systolic, df = 3, F = 7.843, p < 0.001; diastolic, df = 3, F = 5.453, p = 0.002) was observed. The total fall in systolic and diastolic blood pressure amounted to a mean of 15 (SD = 10.4) mm Hg and 10 (SD = 9.7) mm Hg, respectively. In addition, blood pressure fell significantly in response to individual breastfeeding sessions during the entire observation period. CONCLUSIONS: In conclusion, both systolic and diastolic blood pressures fall during a breastfeeding session, and pre-breastfeeding blood pressure decreases during at least the first 6 months of a breastfeeding period in a homelike environment. This study lends further support to the health-promoting effects of breastfeeding.

Newborn skin temperature two days postpartum during breastfeeding related to different labour ward practices.

AIM: To investigate (1) the skin temperature pattern in newborns two days after birth in connection to breastfeeding and to examine (2) if the administration of epidural analgesia (EDA) and oxytocin (OT) infusion during labour influences this parameter at this point of time. METHOD: Forty-seven mother-infant pairs were included in the study: nine mothers had received OT stimulation during labour (OT group), 20 mothers had received an EDA and OT during labour (EDA group), while 18 mothers had received neither EDA nor OT stimulation during labour (control group). A skin temperature electrode was attached between the newborn's shoulder blades. The newborn was placed skin-to-skin on the mother's chest and covered with a blanket. The temperature was recorded immediately after the newborn was put on the mother's chest and at 5, 10, 20 and 30 min. RESULTS: The temperature measured when the newborns were put skin-to-skin on their mothers' chest was significantly higher in the infants of the EDA group (35.07 degrees C) when compared to the control group (34.19 degrees C, p=0.025). Skin temperature increased significantly (p=0.001) during the entire experimental period in the infants belonging to the control group. The same response was observed in infants whose mothers received OT intravenously during labour (p=0.008). No such rise was observed in infants whose mothers were given an EDA during labour. CONCLUSION: The results show that the skin temperature in newborns rises when newborns are put skin-to-skin to breastfeed two days postpartum. This effect on temperature may be hampered by medical interventions during labour such as EDA.

The effect of Russian Maternity Home routines on breastfeeding and neonatal weight loss with special reference to swaddling.

BACKGROUND: Few investigations have considered evaluating the effects of certain combinations of ward routines like swaddling of the baby and separation of mother and baby on infant variables such as neonatal weight loss. AIMS: To study the effect of different ward routines in respect to proximity to mother and type of infant apparel, on breastfeeding parameters (amount of ingested milk, volume of supplements, number of breastfeeds, total duration of breastfeeding time) day 4 after birth as well as recovery from neonatal weight loss and infant's weight on day 5. STUDY DESIGN AND SUBJECTS: In a randomized trial with factorial design four treatment groups including 176 mother-infant dyads were studied 25-120 min after birth. Randomized treatments focused on care routines administered to the infants after delivery and later in the maternity ward as well as to the type of clothing the infants received. Group 1 infants were placed skin-to-skin with their mothers after delivery, and had rooming-in while in the maternity ward. Group 2 infants were dressed and placed in their mothers' arms after delivery, and roomed-in with mothers in the maternity ward. Group 3 infants were kept in the nursery both after birth and while their mothers were in the maternity ward. Group 4 infants were kept in the nursery after birth, but roomed-in with their mothers in the maternity ward. Equal numbers of infants were either swaddled or clothed in baby attire. Breastfeeding parameters were documented during day 4 after birth. Infant's weight was measured daily. RESULTS: Babies who were kept in the nursery received significantly more formula and significantly less breast-milk, than did babies who roomed-in with their mothers. Swaddling did not influence the breastfeeding parameters measured. However, swaddled babies who had experienced a 2-h separation period after birth and then were reunited with their mothers tended to have a delayed recovery of weight loss compared to those infants who were exposed to the same treatment but dressed in clothes. Furthermore, swaddled babies who were kept in the nursery and received breast-milk supplements had a significantly delayed recovery of weight loss after birth when compared to those infants ingesting only breast-milk. On day 5, regression analyses of predicted weight gain in the exclusively breastfed infants indicated a significant increase per 100 ml breast-milk (59 g), compared to the predicted weight gain on day 5 per 100 ml supplements in the swaddled babies (14 g) (P=0.001). CONCLUSION: Supplements given to the infants in the nursery had a negative influence on the amount of milk ingested. In addition, supplement feeding or a short separation after birth when combined with swaddling was shown to have a negative consequence to infant weight gain.

Long-term modulation by postnatal oxytocin of the alpha 2-adrenoceptor agonist binding sites in central autonomic regions and the role of prenatal stress.

The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life-long effects on the alpha(2)-agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the alpha(2)-agonist [(3)H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of alpha(2)-agonist binding sites in the NTS and in the hypothalamus. The K(d) value of the alpha(2)-agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food-restricted dams, oxytocin treatment produced a significant increase of the B(max) values in the hypothalamus and the amygdala and the K(d) value of the alpha(2)-agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin-induced increase of regional alpha(2)-adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central alpha(2)-adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of alpha(2)-adrenoceptor signalling in adulthood may contribute to the anti-stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in alpha(2)-adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the alpha(2)-agonist binding sites in the hypothalamus and the amygdala.

Skin-to-skin contact may reduce negative consequences of "the stress of being born": a study on temperature in newborn infants, subjected to different ward routines in St. Petersburg.

AIM: To evaluate how different delivery-ward routines influence temperature in newborn infants. METHODS: A total of 176 newborn mother-infant pairs were included in a randomized study. The babies were kept skin-to-skin on the mother's chest (Skin-to-skin group), held in their mother's arms, being either swaddled or clothed (Mother's arms group), or kept in a cot in the nursery, being either swaddled or clothed (Nursery group). Temperature was measured in the axilla, on the thigh, back and foot at 15-min intervals at from 30 to 120 min after birth. RESULTS: During this time period the axilla, back and thigh temperatures rose significantly in all the treatment groups. The foot temperature displayed a significant fall in the babies in the Nursery group and this decrease was greatest in the swaddled babies. In contrast, foot temperature rose in the babies in the Mother's arms group and in particular in babies in the Skin-to-skin group. Foot temperature remained high in the Skin-to-skin group, whereas the low temperature observed in the Nursery group gradually increased and two days after birth the difference was no longer significant. CONCLUSION: The results show that delivery-ward routines influence skin temperature in infants in the postnatal period. Allowing mother and baby the ward routine of skin-to-skin contact after birth may be a "natural way" of reversing stress-related effects on circulation induced during labour.

Effect of suckling on the release of oxytocin, prolactin, cortisol, gastrin, cholecystokinin, somatostatin and insulin in dairy cows and their calves.

The aim of the present study was to examine how different types of early interaction between dairy cows and their calves influence milking/suckling-related hormone release in the cows and sucking/bucket-drinking related hormone release in calves. Eighteen cows of the Swedish Red and White breed were studied during the first week after parturition. The cows were machine milked twice daily, and allotted to one of three treatments: [1] cow and calf were kept together and the cow was allowed to suckle the calf for 30 min about 1 h before each milking; [2] cow and calf were kept together and the calf was bucket fed twice daily; and [3] cow and calf were separated immediately after parturition, and the calf was kept in a single box and was bucket fed twice daily. Blood samples were collected around day 7 from both cows and calves. The plasma levels of oxytocin, prolactin, cortisol, gastrin, cholecystokinin (CCK), somatostatin and insulin were analysed. In the cows the levels of oxytocin, prolactin and cortisol were influenced by all three treatments, except for the level of cortisol which did not respond to suckling. The main finding was that the release of oxytocin was as significantly greater during suckling compared with machine milking. In the calves, the hormone levels were also influenced by the different milk feeding routines. The plasma concentrations of oxytocin, gastrin, CCK and insulin increased in response to milk ingestion in all treatments. However, during sucking, the increase of oxytocin was significantly greater than during bucket drinking. In addition, a strong correlation between oxytocin and insulin was found in response to sucking. Further, significant increases in prolactin and somatostatin, and a decrease in cortisol were found during sucking. The level of somatostatin also increased in response to bucket feeding when calves were kept separately. During bucket feeding, no significant correlation was found with oxytocin, but strong correlations between the gastrointestinal hormones gastrin, CCK, somatostatin and insulin were seen. Together these data suggest that different hormonal patterns were triggered in the cows by suckling and milking and in the calves by sucking and bucket drinking. This is further supported by different correlation patterns observed in the calves in response to sucking and bucket feeding. The present findings imply that management routines for cows and calves during the first week after parturition have consequences for the physiology of the animals.

Oxytocin decreases carrageenan induced inflammation in rats.

The effects of oxytocin on carrageenan-induced inflammation in rat hindpaw was examined. Oxytocin at 100 (P < 0.05) and 1000 microg/kg s.c. (P < 0.05), but not at 1 and 10 microg/kg s.c., reduced the edema of the paw when measured up to 10 h after the injection. An additional experiment showed that the effect was comparable to the effect of the glucocorticoid dexamethasone. No effect was found by oxytocin i.c.v. In addition, rats with carrageenan-induced inflammation given oxytocin (1000 microg/kg s.c.) responded differently to nociceptive mechanical stimulation (P < 0.05) and had a reduced amount of myeloperoxidase (marker for neutrophil recruitment) in the paw (P < 0.01).

Oxytocin facilitates behavioural, metabolic and physiological adaptations during lactation.

The aim of this article is to propose that oxytocin not only stimulates milk let down, but also adapts behaviour and physiology to facilitate lactation in mammals including dairy cattle. Circulating oxytocin as well as neurogenic oxytocin participates in these regulatory processes. In short, oxytocin stimulates maternal interaction and attachment between mother and young. It also participates in the metabolic prerequisites for milk production by e.g. stimulating glucagon release and thereby, mobilisation of glucose. Digestive and anabolic aspects of metabolism are also stimulated, e.g. by increased vagal nerve activity. Adaptations consistent with an antistress like pattern are also induced. Cortisol levels are decreased as well as blood pressure, and behaviours characterised by calm, reduced levels of anxiety and more social activity are promoted. These effects seem to be present in monogastric animals as well as in ruminants. The expression of various aspects of these adaptations vary according to the special needs and living environmental circumstances of different species. The mechanisms behind the effect spectrum of oxytocin are being explored in other experimental models. A second aim of this paper is to suggest that efficiency of lactation can be promoted by facilitating oxytocin release in connection with milking by enhancing the amount of sensory stimulation.

Maternal analgesia during labor disturbs newborn behavior: effects on breastfeeding, temperature, and crying.

BACKGROUND: Newborns not exposed to analgesia, when placed on the mother's chest, exhibit an inborn prefeeding behavior. This study was performed to assess the effects of different types of analgesia during labor on the development of spontaneous breastfeeding movements, crying behavior, and skin temperature during the first hours of life in healthy term newborns. METHODS: Video recordings were made of 28 newborns who had been dried and placed in skin-to-skin contact between their mother's breasts immediately after delivery. The video recordings were analyzed blindly with respect to infant exposure to analgesia. Defined infant behaviors were assessed every 30 seconds. Group 1 mothers (n = 10) had received no analgesia during labor, group 2 mothers (n = 6) had received mepivacaine via pudendal block, and group 3 mothers (n = 12) had received pethidine or bupivacaine or more than one type of analgesia during labor. RESULTS: All infants made finger and hand movements, but the infant's massagelike hand movements were less frequent in infants whose mothers had received labor analgesia. A significantly lower proportion of group 3 infants made hand-to-mouth movements (p < 0.001), and a significantly lower proportion of the infants in groups 2 and 3 touched the nipple with their hands before suckling (p < 0.01), made licking movements (p < 0.01), and sucked the breast (p < 0.01). Nearly one-half of the infants, all in groups 2 or 3, did not breastfeed within the first 2.5 hour of life. The infants whose mothers had received analgesia during labor had higher temperatures (p = 0.03) and they cried more (p = 0.05) than infants whose mothers had not received any analgesia. CONCLUSIONS: The present data indicate that several types of analgesia given to the mother during labor may interfere with the newborn's spontaneous breast-seeking and breastfeeding behaviors and increase the newborn's temperature and crying.

Postpartum maternal oxytocin release by newborns: effects of infant hand massage and sucking.

BACKGROUND: Newborns placed skin-to-skin with their mothers show an inborn sequence of behavior similar to that seen in other mammals. The purpose of this study was to make a detailed exploration of hand movements and sucking behavior in healthy term newborns who were placed skin-to-skin on their mothers' chests, and to study maternal oxytocin release in relation to these behaviors. METHODS: Ten vaginally delivered infants whose mothers had not been exposed to maternal analgesia were video-recorded from birth until the first breastfeeding. Video protocols were developed based on observations of the videotapes. Each infant's hand, finger, mouth, and tongue movements, positions of the hand and body, and sucking behavior were assessed every 30 seconds. Maternal blood samples were collected every 15 minutes, and oxytocin levels were analyzed by radioimmunoassay. A statistical test for establishing the relationship between maternal oxytocin levels and infants' hand movements or sucking behavior was developed. RESULTS: Infants used their hands to explore and stimulate their mother's breast in preparation for the first breastfeeding. A coordinated pattern of infant hand and sucking movements was also identified. When the infants were sucking, the massagelike hand movements stopped and started again when the infants made a sucking pause. Periods of increased massagelike hand movements or sucking of the mother's breast were followed by an increase in maternal oxytocin levels (p < 0.005). CONCLUSIONS: The findings indicate that the newborns use their hands as well as their mouths to stimulate maternal oxytocin release after birth, which may have significance for uterine contraction, milk ejection, and mother-infant interaction.

Plasma oxytocin and cortisol concentrations in dairy cows in relation to feeding duration and rumen fill.

The aim of this study was to investigate if the release of oxytocin and cortisol were different depending on levels of oral manipulation with feed or rumen fill in dairy cows. Blood samples and behavior of 12 rumen-fistulated cows were analyzed in 2 consecutive years during morning and afternoon periods when the cows were subjected to either (A) long duration of oral manipulation of feed with low rumen fill or (B) short duration of oral manipulation of feed but with filled rumen. The response areas under the curve for oxytocin in both years were larger in A than in B in the afternoons. There were peaks in oxytocin release at milking in the afternoon in both treatments. In B, the oxytocin concentration was higher after than before feeding, higher in B than in A after the non-oral rumen filling, and higher in B after than before the non-oral rumen filling in Year 1. The level of cortisol was higher in B than in A in the morning, lower in both treatments before than after milking in the afternoon, and there was a tendency for the cortisol level to be higher in A than in B after oral feeding. The B cows spent a shorter time eating and the A cows spent a shorter time ruminating. This study indicates that a long duration of oral manipulation of feed in cows, may, per se be linked to higher oxytocin but lower cortisol levels, compared with shorter oral feeding time and filled rumen.

Antagonistic oxytocin/alpha2-adrenoreceptor interactions in the nucleus tractus solitarii: relevance for central cardiovascular control.

The modulation of the central cardiovascular effects of alpha2-adrenoceptor activation by oxytocin in the nucleus tractus solitarii has been evaluated by cardiovascular analysis and by quantitative receptor autoradiography. Microinjections in the nucleus tractus solitarii of a threshold dose of oxytocin effectively and significantly counteracted the vasodepressor and bradycardic actions of an ED50 dose of the alpha2-adrenoceptor agonist clonidine. The coinjection of a threshold dose of oxytocin with a threshold dose of clonidine did not produce any changes in the mean arterial pressure but a tachycardic response was observed. Receptor autoradiographical experiments showed that oxytocin (3 nM) significantly increased the Kd and Bmax values of [3H]p-aminoclonidine binding sites in the nucleus tractus solitarii compatible with a possible antagonistic interaction with the alpha2-adrenoceptors, and this effect was blocked by the presence of the specific oxytocin receptor antagonist 1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-oxytocin. These findings suggest the existence of an antagonistic oxytocin/alpha2-adrenoceptor interaction in nucleus tractus solitarii that may be of relevance for the demonstrated modulation of alpha2-adrenoceptor induced cardiovascular responses by oxytocin.

Changes in personality pattern during the first pregnancy and lactation.

In order to study personality changes in first pregnancy and lactation, two groups of women (n = 161, mean age 26.8 years) completed the self-report inventory Karolinska Scales of Personality and a scale for emotional dependency during pregnancy and 3 or 6 months after delivery. The results were within normal limits when compared with the normative values. Analysis of variance showed that the subscales Muscular Tension, Somatic Anxiety, and Monotony Avoidance diminished significantly from pregnancy and to the test periods after delivery (all p values < 0.01). Impulsiveness showed the same trend (p = 0.1). The women who had breastfed for at least 8 weeks (91%) differed significantly from those who had not. They had lower scores on the Somatic Anxiety (p = 0.006), Muscular Tension (p = 0.003), Monotony Avoidance (p = 0.039), Suspicion (p = 0.03), Social Desirability (p = 0.045) and the Impulsiveness scale (p = 0.078) and higher scores on the Socialization scale (p = 0.001). Thus, we conclude that most personality traits are stable during first pregnancy and lactation, but some significant changes occur toward a lifestyle interpreted as more relaxed and tolerant to monotony.

Effects of oxytocin treatment in early life on body weight and corticosterone in adult offspring from ad libitum-fed and food-restricted rats.

The aims of this study were: (1) to assess the effects of maternal undernutrition during pregnancy on adult offspring with regard to growth, body composition and plasma levels of glucose, insulin and corticosterone, and (2) to investigate whether oxytocin treatment early in life could ameliorate the adverse effects of food restriction in utero. Pups from ad libitum-fed and food-restricted (60% of ad libitum intake during pregnancy) rats were injected subcutaneously once a day with oxytocin or saline on days 1-14 after birth. At adult age (62 days), male offspring from food-restricted dams had lower body weight, less adipose tissue, lower plasma glucose but higher corticosterone levels, compared to offspring from ad libitum-fed dams. However, oxytocin-treated food-restricted males had higher body weight, higher glucose and lower corticosterone levels compared to their saline-treated counterparts. In conclusion, oxytocin treatment early in life seems to ameliorate some of the adverse effects of food restriction in utero.

Improved conditioned avoidance learning by oxytocin administration in high-emotional male Sprague-Dawley rats.

OBJECTIVE: To examine anti-stress-like properties of oxytocin as a means to improve conditioned avoidance learning in a low-performing, high-emotional, stock of Sprague-Dawley male rats. METHODS: Adult male rats of two stocks of the Sprague-Dawley strain, designated Stock A and Stock B, were treated daily with oxytocin (1 mg kg(-1) s. c.) for 5 days preceding four daily conditioned avoidance acquisition sessions (approximately 20 trials per 15 min session). The Stock B animals were previously characterized as high-emotional based on [1] elevated plasma corticosterone, and lowered plasma oxytocin, levels and [2] decreased reaction time and an increased startle amplitude to an acoustic stimulation. Finally, [3] these animals were unable to acquire a conditioned avoidance response within 5 days of training. RESULTS: The Stock A animals rapidly and statistically significantly acquired the avoidance behaviour within 4 days of daily training, whereas Stock B animals did not improve over this time period. The avoidance performance of Stock B animals was markedly and statistically significantly improved by the oxytocin pre-treatment, whereas the performance of Stock A animals was not affected by the same oxytocin treatment. CONCLUSIONS: Pre-treatment with oxytocin markedly improved avoidance learning in the Stock B high-emotional animals. It is suggested that the improvement is due to previously demonstrated anti-stress-like properties of oxytocin, rendering the animals able to successfully cope with the demands of the conditioned avoidance situation.

Oxytocin/alpha(2)-Adrenoceptor interactions in feeding responses.

The modulation of alpha(2)-adrenoceptor-induced food intake by oxytocin has been evaluated in studies on food intake and by quantitative receptor autoradiography in the hypothalamus and the amygdala of the rat. The effects of lateral intracerebroventricular administration of clonidine and oxytocin were evaluated on food intake in satiated animals. Food consumption was measured at 30, 90, 240 min and 22 h (1,320 min) after injection. The coinjection of oxytocin and clonidine was found to counteract the increase in food intake produced by clonidine (p < 0.001) in satiated rats. Receptor autoradiographic experiments showed that oxytocin significantly increased the K(d) values of [(3)H]p-aminoclonidine alpha(2)-agonist-binding sites in the hypothalamus. Effective oxytocin concentrations ranged between 0.3 and 1 nM (p < 0.05) with a maximal action of 250% at 1 nM. The B(max) value was significantly increased (p < 0.05) for all concentrations of oxytocin. In the amygdala, oxytocin also increased both the K(d) of [(3)H]p-aminoclonidine-binding sites by about 190% at 1 nM and the B(max) values at 1 and 3 nM (p < 0.05). Oxytocin (1 nM) also significantly and substantially (p < 0.01) increased the K(d) and B(max) values of the [(3)H]UK 14.304 alpha(2)-agonist-binding sites in the hypothalamus and amygdala in agreement with the results obtained with the other agonist of the alpha(2)-adrenoceptor [(3)H]p-aminoclonidine. This effect was partially blocked by the presence of the specific oxytocin receptor antagonist, CAP. These findings suggest the existence of an antagonistic oxytocin/alpha(2)-receptor interaction in the hypothalamus and amygdala that may be of relevance for the demonstrated modulation of alpha(2)-adrenoceptor-induced feeding responses by oxytocin.

Associations between plasma glucose and DSM-III-R cluster B personality traits in psychiatric outpatients.

Associations between personality traits, measured with the Karolinska Scales of Personality, the Impulsiveness subscale from the Impulsiveness, Venturesomeness and Empathy (IVE) Inventory, and with self-assessed personality traits and disorders (SCID-II Screen Questionnaire), and plasma insulin, glucagon and glucose, respectively, were explored in a sample of 101 psychiatric outpatients of both sexes. No relationships between the peptide hormones and personality measures were found. However, fasting glucose values, which were all essentially within the normal biological variation, were significantly related to several personality measures. For males, a low blood glucose was associated with low stable general level of functioning, with high IVE Impulsiveness, and with self-assessed histrionic and narcissistic traits. High number of self-assessed personality traits for all cluster B personality disorders was strongly associated with high IVE Impulsiveness. The results of the present study support the generalizability of earlier findings from alcoholic impulsive offenders: in males, low blood glucose is associated with an extrovert and impulsive, acting-out behavior that includes the breaking of societal norms and rules. In contrast, for females a positive relationship between fasting glucose and self-assessed histrionic personality traits was found. Because no association between global level of functioning and glucose was found in women, these personality traits may not necessarily be maladaptive, as was the case for males.

Systemic oxytocin treatment modulates alpha 2-adrenoceptors in telencephalic and diencephalic regions of the rat.

Systemic subchronic oxytocin treatment significantly and substantially increased the B(max) values of the alpha 2 agonist [(3)H]UK14.304 binding sites in the hypothalamus, the amygdala and the paraventricular thalamic nucleus of the rat as shown by quantitative receptor autoradiography. These results suggest that long-term modulation of autonomic and neuroendocrine functions and emotional behaviours elicited by brain oxytocin may involve enhancement of central alpha 2-adrenoceptor function.