Plasma Prolactin Concentrations Research Articles

Hormonal Profile in Overweight Cats: Retrospective Study

Overweight is defined as a 15 % excess body weight (BW) relative to ideal BW. This nutritional disorder could result from dysregulated metabolism orientation toward anabolism. The aim of the study was to investigate the endocrine profile of naturally-acquired obesity in cats. One hundred and ninety four client-owned cats (males= 2 intact and 80 castrated, females= 13 intact and 99 neutered; mean age = 6.8 ± 3.1 y; mean BW = 8.0 ± 1.0 kg) were enrolled. The overweight had been estimated (蠅15 % ideal BW) by veterinarians. Blood samples were collected before and 1h30 after IM tetracosactide injection used as stimulant of adrenal glands secretion. Plasma cortisol, insulin-like growth factor (IGF1), insulin, leptin and prolactin concentrations have been determined. ANOVA and Pearson's correlation analysis was performed to assess the effect of BW, gender and age on hormonal concentration. Plasma IGF1, leptin and prolactin concentrations were higher than the reference range in 60 %, 38 % and 51 % of the cats, respectively. According to insulin and glycemia values, 23 % of cats were insulin resistant and 2 % diabetic. The BW, IGF1 and insulin concentration was significantly higher in male than in female cats. The BW and insulin concentration significantly changed with age. The BW was positively correlated with plasma IGF1, leptin and insulin concentrations. The results show that overweight in cats is an endocrinopathy. These hormonal disorders could increase the risk of pathological conditions onset and also shorten life span. Management of feline obesity should then include an endocrine evaluation that could be useful for the prescription of nutritional and medical treatment.

Ultrastructural changes in lactotrophs and folliculo-stellate cells in the ovine pituitary during the annual reproductive cycle.

In seasonal mammals living in temperate zones, photoperiod regulates prolactin secretion, such that prolactin plasma concentrations peak during the summer months and are lowest during the winter. In sheep, a short-day breeder, circulating prolactin has important modulatory effects on the reproductive system via inhibitory actions on pituitary gonadotrophs and hypothalamic gonadotrophin-releasing hormone release. The exact cellular mechanisms that account for the chronic hypersecretion of prolactin during the summer is not known, although evidence supports an intrapituitary mechanism regulated by melatonin. Folliculo-stellate (FS) cells are non-endocrine cells that play a crucial role in paracrine communication within the pituitary and produce factors controlling prolactin and gonadotrophin release. The present study examined the morphology of the FS and lactotroph cell populations and their distribution in the sheep pituitary during the annual reproductive cycle. Ovine pituitary glands were collected in the winter (breeding season; BS) and summer (nonbreeding season; NBS) and were prepared for quantitative electron microscopy to assess the effects of season on FS and lactotroph cell density, morphology and distribution, as well as on junctional contacts between cells. It was found that lactotrophs in the NBS are larger in size and contain more numerous PRL granules than lactotrophs in the BS. FS cells were also larger in the NBS compared to BS and showed altered morphology such that, in the BS, long cell processes surrounded clusters of adjacent secretory cells. Although no significant change in the number of junctions was observed between lactotrophs and FS cells, or lactotrophs and gonadotrophs, there was a significant increase in the number of adherens junctions between lactotrophs and between FS cells. These findings demonstrate seasonal plasticity in the morphology of lactotrophs and FS cells that reflect changes in PRL secretion.

Effects of an extended photoperiod on gonadal function and condition of hair coats in Thoroughbred colts and fillies

ABSTRACTThe effects of an extended photoperiod (EP) in Thoroughbreds colts and fillies from winter at one year old to spring at two years old on the gonadal functions, coat condition, and endocrine changes were investigated. Sixty-two Thoroughbreds (31 colts and 31 fillies) reared in the Hidaka Training and Research Center (Hidaka), Japan Racing Association were used. Thirty of them (15 colts and 15 fillies) were reared under EP conditions from December 20 to April 10, and the remaining 32 horses were reared under natural light alone as a control group. For EP, a 100-watt white bulb was set near the ceilings of stalls, and lighting conditions of 14.5-hr light and 9.5-hr dark periods were established. Blood was collected from the jugular vein once a month from October at one year old to February at two years old in both colts and fillies, and then twice a month in colts and weekly in fillies after March, and the coat condition was evaluated in January and April in 56 horses. To investigate endocrine changes, the plasma concentrations of prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), immunoreactive (ir-) inhibin, testosterone, estradiol-17β and progesterone were measured. No significant difference was noted in the coat condition between the two groups in January, but they changed from winter to summer coats (molting of winter coats) in April in the EP group compared with the control group. Regarding endocrine changes, the plasma concentrations of prolactin, FSH, ir-inhibin and testosterone were significantly higher in the EP colts than in the control group from January to April. The plasma concentrations of LH tended to rise in the EP colts from January to April compared with the control group. In the EP fillies, the plasma concentrations of prolactin, LH, ir-inhibin, estradiol-17β and progesterone were significantly higher during January and April, but a significantly high level of FSH was noted in the control than EP group in January. The ovulation day was advanced in the EP fillies compared with the control group. The present study clearly demonstrated that EP treatment during rearing advanced the molting of winter coats in both colts and fillies. These results suggested to be due to the action of prolactin being increased by EP treatment. In addition, EP treatment stimulated the hypothalamus-pituitary-gonadal axis even in yearlings, and advanced ovulation in fillies. Since EP treatment-induced changes in the yearlings were within the physiological range, and the method is safe and simple, EP treatment may be an effective technique in horse husbandry.

Monitoring blood plasma leptin and lactogenic hormones in pregnant sows

The mechanism of action of leptin in pregnant breeding sows, in which hyperphagia is managed through dietary strategies, is yet to be clarified. The aim of this study was to monitor leptin concentrations and their interactions with lactogenic hormones in Large White×Landrace breeding multiparous sows (n=15). All sows showed a normal body condition (mean body condition score: 2.96). Blood samples were collected the day after weaning the litters, at insemination, every 15 days up to day 45 of pregnancy and every 7 days from day 46 to farrowing. At delivery, the placenta was collected for the analysis of leptin and leptin receptor expressions. Plasma leptin levels increased from the end of mid gestation (day 72) and remained high until farrowing (P<0.05). As expected, plasma prolactin (PRL), low during most of pregnancy, increased during the 2 weeks before farrowing (P<0.05), whereas progesterone levels reached plateau at 30 days of gestation and decreased at farrowing (P<0.05). Cortisol levels peaked close to farrowing (P<0.05). Leptin was expressed in the placenta, where the receptor expression analysis showed the presence of the short form but not of the long form. A positive correlation was found between leptin and PRL concentrations during mid (r=0.430; P<0.001) and late (r=0.687; P<0.001) pregnancy, and with progesterone in early pregnancy (r=0.462; P<0.05). During late gestation, a positive correlation was observed between leptin and cortisol (r=0.585; P<0.001). Our results suggested that, in restrictively fed pregnant sows, the leptin levels increased from the end of mid pregnancy to delivery, confirming the presence of leptin resistance. We showed a correlation between leptin and lactogenic hormones during different stages of pregnancy in sows. Lactogenic hormones show pregnancy-specific changes in their secretion and all may become involved in modulating leptin signal.

Alcohol consumption in relation to plasma sex hormones, prolactin, and sex hormone-binding globulin in premenopausal women.

Alcohol consumption is a consistent risk factor for breast cancer, and evidence suggests premenopausal plasma hormones are associated with breast cancer. Plasma concentrations of estradiol, estrone, estrone sulfate, testosterone, androstenedione, progesterone, prolactin, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and sex hormone-binding globulin (SHBG) were measured in samples collected in 1996-99. Average alcohol intake was calculated from semiquantitative food frequency questionnaires collected in 1995 and 1999. We used generalized linear models to calculate geometric mean hormone concentrations across alcohol categories and the percentage difference for the highest versus lowest category. Comparing women who consumed >20 g/d with nondrinkers, levels were 25.7% higher for luteal estrone (geometric mean, 106 vs. 84.5 pg/mL; Ptrend = 0.001), 27.2% higher for luteal estradiol (182 vs. 143 pg/mL; Ptrend = 0.006), and 16.8% higher for SHBG (85.6 vs. 73.3 nmol/L; Ptrend = 0.03); concentrations of free testosterone were 17.9% lower (0.16 vs. 0.20 ng/dL; Ptrend = 0.002). Women consuming >10 g/d compared with nondrinkers had 26.5% higher concentrations of follicular estrone sulfate (950 vs. 751 pg/mL; Ptrend = 0.04). We did not observe significant associations between alcohol and the other sex hormones evaluated. Significant positive associations were observed with beer intake, but not other alcohol types, for DHEA (Pinteraction = 0.003) and androstenedione (Pinteraction = 0.006). Alcohol consumption was significantly positively associated with plasma luteal estrogen concentrations, but not with androgen levels, nor estrone or estradiol measured in the follicular phase. Differences in premenopausal estrogen levels may contribute to the association between alcohol and breast cancer.

Suckling and salsolinol attenuate responsiveness of the hypothalamic-pituitary-adrenal axis to stress: focus on catecholamines, corticotrophin-releasing hormone, adrenocorticotrophic hormone, cortisol and prolactin secretion in lactating sheep.

In mammals, the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to stress is reduced during lactation and this mainly results from suckling by the offspring. The suckling stimulus causes a release of the hypothalamic 1-metyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol) (a derivative of dopamine), one of the prolactin-releasing factors. To investigate the involvement of salsolinol in the mechanism suppressing stress-induced HPA axis activity, we conducted a series of experiments on lactating sheep, in which they were treated with two kinds of isolation stress (isolation from the flock with lamb present or absent), combined with suckling and/or i.c.v infusion of salsolinol and 1-methyl-3,4-dihydro-isoqinoline (1-MeDIQ; an antagonistic analogue of salsolinol). Additionally, a push-pull perfusion of the infundibular nucleus/median eminence (IN/ME) and blood sample collection with 10-min intervals were performed during the experiments. Concentrations of perfusate corticotrophin-releasing hormone (CRH) and catecholamines (noradrenaline, dopamine and salsolinol), as well as concentrations of plasma adenocorticotrophic hormone (ACTH), cortisol and prolactin, were assayed. A significant increase in perfusate noradrenaline, plasma ACTH and cortisol occurred in response to both kinds of isolation stress. Suckling and salsolinol reduced the stress-induced increase in plasma ACTH and cortisol concentrations. Salsolinol also significantly reduced the stress-induced noradrenaline and dopamine release within the IN/ME. Treatment with 1-MeDIQ under the stress conditions significantly diminished the salsolinol concentration and increased CRH and cortisol concentrations. Stress and salsolinol did not increase the plasma prolactin concentration, in contrast to the suckling stimulus. In conclusion, salsolinol released in nursing sheep may have a suppressing effect on stress-induced HPA axis activity and peripheral prolactin does not appear to participate in its action.

The effects of additional treatment with terguride, a partial dopamine agonist, on hyperprolactinemia induced by antipsychotics in schizophrenia patients: a preliminary study.

Hyperprolactinemia is a frequent consequence of treatment with antipsychotics. Earlier studies have indicated that terguride, which is a partial dopamine agonist, reduces the prolactin levels that are induced by prolactinemia. Thus, we examined the dose effects of adjunctive treatment with terguride on the plasma concentrations of prolactin in patients with elevated prolactin levels resulting from antipsychotic treatment. Terguride was concomitantly administered to 20 schizophrenic patients (10 males and 10 females) receiving paliperidone and risperidone. The dose of terguride was 1.0 mg/day. Sample collections for prolactin were conducted before terguride (baseline) and 2–4 weeks after administration. The samples were obtained after the morning dose of terguride. The average (± standard deviation) plasma prolactin concentration during terguride coadministration was significantly lower than the baseline concentration in females (82.3±37.1 ng/mL versus 56.5±28.5 ng/mL, P<0.01) but not in males (28.8±18.0 ng/mL versus 26.2±13.1 ng/mL, not significant). Additionally, a significant correlation between the ratio of prolactin reduction and the baseline prolactin concentration was identified in males (rs=−0.638, P<0.05) but not in females (rs=−0.152, not significant). Many patients complained of various adverse events following terguride administration, such as insomnia, agitation, and/or the aggravation of hallucinations. This study suggests that additional treatment with terguride decreases the prolactin concentrations in females experiencing high prolactin levels as a result of antipsychotic treatment. However, its utility for schizophrenia may be diminished because of its low tolerability.

Disruption of behavioral circadian rhythms induced by psychophysiological stress affects plasma free amino acid profiles without affecting peripheral clock gene expression in mice

Disordered circadian rhythms are associated with various psychiatric conditions and metabolic diseases. We recently established a mouse model of a psychophysiological stress-induced chronic sleep disorder (CSD) characterized by reduced amplitude of circadian wheel-running activity and sleep–wake cycles, sleep fragmentation and hyperphagia. Here, we evaluate day–night fluctuations in plasma concentrations of free amino acids (FAA), appetite hormones and prolactin as well as the hepatic expression of circadian clock-related genes in mice with CSD (CSD mice). Nocturnal increases in wheel-running activity and circadian rhythms of plasma prolactin concentrations were significantly disrupted in CSD mice. Hyperphagia with a decreased leptin/ghrelin ratio was found in CSD mice. Day–night fluctuations in plasma FAA contents were severely disrupted without affecting total FAA levels in CSD mice. Nocturnal increases in branched-chain amino acids such as Ile, Leu, and Val were further augmented in CSD mice, while daytime increases in Gly, Ala, Ser, Thr, Lys, Arg, His, Tyr, Met, Cys, Glu, and Asn were significantly attenuated. Importantly, the circadian expression of hepatic clock genes was completely unaffected in CSD mice. These findings suggest that circadian clock gene expression does not always reflect disordered behavior and sleep rhythms and that plasma FFA profiles could serve as a potential biomarker of circadian rhythm disorders.

Plasma amino acids, prolactin, insulin and glucose concentrations in lactating sows following venous infusion of isoleucine, leucine, lysine, threonine or valine

de Ridder, K. A. G., Farmer, C., de Lange, C. F. M., Shoveller, A. K. and Luimes, P. H. 2014. Plasma amino acids, prolactin, insulin and glucose concentrations in lactating sows following venous infusion of isoleucine, leucine, lysine, threonine or valine. Can. J. Anim. Sci. 94: 323–330. The amino acid supply to lactating sows affects their milk yield, and the current study aims at establishing whether this is mediated via increases in concentrations of insulin and prolactin, two hormones that are important for lactation. Six multiparous Yorkshire sows (252.8±18.5 kg body weight) were fitted with an ear vein catheter and were used in a 6×6 Latin square design experiment from days 7 to 10 of lactation (am and pm infusions on 3 consecutive days). Sows were fed a commercial corn and soybean meal diet (17.1% crude protein) three times daily (1.5 kg at 0600 and 1200, 3.0 kg at 1830). Starting 2 h after the 0600 or 1200 feeding, sows received an infusion of saline (control), isoleucine, leucine, lysine, threonine or valine at a rate of 33 mL min−1during 30 min. The infused dose was equivalent to 18±0.9% of true ileal digestible intake for each of the amino acids. Serial blood samples were taken, starting 30 min prior to infusion and until 240 min after infusion. Plasma concentrations of amino acids, prolactin, insulin, and glucose were determined. Data were analyzed as repeated measurements and also using areas under the curve. Intravenous infusion with each of the five amino acids studied increased the corresponding free plasma amino acid concentrations (P&lt;0.05). However, concentrations of prolactin, insulin, and glucose were not affected by infusion of any of the amino acids studied (P&gt;0.10). Therefore, supplying intravenously 18% of the daily intake of isoleucine, leucine, lysine, threonine or valine brings about expected increases in amino acids, but does not alter the short-term response in prolactin, insulin or glucose concentrations of lactating sows.

The Medial Amygdala-Medullary PrRP-Synthesizing Neuron Pathway Mediates Neuroendocrine Responses to Contextual Conditioned Fear in Male Rodents

Fear responses play evolutionarily beneficial roles, although excessive fear memory can induce inappropriate fear expression observed in posttraumatic stress disorder, panic disorder, and phobia. To understand the neural machineries that underlie these disorders, it is important to clarify the neural pathways of fear responses. Contextual conditioned fear induces freezing behavior and neuroendocrine responses. Considerable evidence indicates that the central amygdala plays an essential role in expression of freezing behavior after contextual conditioned fear. On the other hand, mechanisms of neuroendocrine responses remain to be clarified. The medial amygdala (MeA), which is activated after contextual conditioned fear, was lesioned bilaterally by infusion of N-methyl-d-aspartate after training of fear conditioning. Plasma oxytocin, ACTH, and prolactin concentrations were significantly increased after contextual conditioned fear in sham-lesioned rats. In MeA-lesioned rats, these neuroendocrine responses but not freezing behavior were significantly impaired compared with those in sham-lesioned rats. In contrast, the magnitudes of neuroendocrine responses after exposure to novel environmental stimuli were not significantly different in MeA-lesioned rats and sham-lesioned rats. Contextual conditioned fear activated prolactin-releasing peptide (PrRP)-synthesizing neurons in the medulla oblongata. In MeA-lesioned rats, the percentage of PrRP-synthesizing neurons activated after contextual conditioned fear was significantly decreased. Furthermore, neuroendocrine responses after contextual conditioned fear disappeared in PrRP-deficient mice. Our findings suggest that the MeA-medullary PrRP-synthesizing neuron pathway plays an important role in neuroendocrine responses to contextual conditioned fear.

Androgen Receptor Gene CAG Repeat Polymorphism Independently Influences Recovery of Male Sexual Function After Testosterone Replacement Therapy in Postsurgical Hypogonadotropic Hypogonadism

Few and contradictory studies have evaluated the possible influence of androgen receptor (AR) gene CAG repeat polymorphism on male sexual function. In this study we evaluated the role of AR gene CAG repeat polymorphism in the recovery of sexual function after testosterone replacement therapy (TRT) in men affected by postsurgical hypogonadotropic hypogonadism, a condition which is often associated with hypopituitarism and in which the sexual benefits of TRT must be distinguished from those of pituitary-function replacement therapies. Fifteen men affected by postsurgical hypogonadotropic hypogonadism were retrospectively assessed before and after TRT. Main outcome measures included sexual parameters as assessed by the International Index of Erectile Function questionnaire, levels of pituitary dependent hormones (total testosterone, free T3, free T4, cortisol, insulin-like growth factor-1 [IGF-1], prolactin), and results of genetic analysis (AR gene CAG repeat number). Plasma concentrations of free T3, free T4, cortisol, and prolactin did not vary significantly between the two phases, while testosterone and IGF-1 increased significantly after TRT. A significant improvement in all sexual parameters studied was found. The number of CAG triplets was negatively and significantly correlated with changes in all the sexual parameters, while opposite correlations were found between changes in sexual parameters and changes in testosterone levels; no correlation of change in IGF1 with change in sexual parameters was reported. On multiple linear regression analysis, after correction for changes in testosterone, nearly all the associations between the number of CAG triplets and changes in sexual parameters were confirmed. Shorter length AR gene CAG repeat number is associated with the recovery of sexual function after TRT in postsurgical male hypogonadotropic hypogonadism, independently of the effects of concomitant pituitary-replacement therapies.

Neuroendocrine and sympathetic responses to an orexin receptor antagonist, SB-649868, and alprazolam following insulin-induced hypoglycemia in humans.

RationaleThe orexin-hypocretin system is important for translating peripheral metabolic signals and central neuronal inputs to a diverse range of behaviors, from feeding, motivation and arousal, to sleep and wakefulness. Orexin signaling is thus an exciting potential therapeutic target for disorders of sleep, feeding, addiction, and stress.Objectives/methodsHere, we investigated the low dose pharmacology of orexin receptor antagonist, SB-649868, on neuroendocrine, sympathetic nervous system, and behavioral responses to insulin-induced hypoglycemic stress, in 24 healthy male subjects (aged 18–45 years; BMI 19.0–25.9 kg/m2), using a randomized, double-blind, placebo-controlled, within-subject crossover design. Alprazolam, a licensed benzodiazepine anxiolytic, was used as a positive comparator, as it has previously been validated using the insulin tolerance test (ITT) model in humans.ResultsOf the primary endpoints, ITT induced defined increases in pulse rate, plasma cortisol, and adrenocorticotropic hormone in the placebo condition, but these responses were not significantly impacted by alprazolam or SB-649868 pre-treatment. Of the secondary endpoints, ITT induced a defined increase in plasma concentrations of adrenaline, noradrenaline, growth hormone (GH), and prolactin in the placebo condition. Alprazolam pre-treatment significantly reduced the GH response to ITT (p < 0.003), the peak electromyography (p < 0.0001) and galvanic skin response (GSR, p = 0.04) to acoustic startle, the resting GSR (p = 0.01), and increased appetite following ITT (p < 0.0005). SB-649868 pre-treatment produced no significant results.ConclusionWe concluded that the ITT model may be informative for assessing the effects of drugs directly acting on the neuroendocrine or sympathetic nervous systems, but could not be validated for studying low dose orexin antagonist activity.Electronic supplementary materialThe online version of this article (doi:10.1007/s00213-014-3520-7) contains supplementary material, which is available to authorized users.

Mouth rinsing with branched‐chain amino acids and carbohydrates on steady‐state metabolism, exercise performance, and the endocrine responses to exercise (634.6)

Previous research suggests that mouth rinsing carbohydrates (CHO) improves exercise performance. The mechanisms for the improvement are not yet known, but may involve maintenance of insulin concentrations during exercise or attenuation of centrally‐mediated fatigue from putative, caloric‐responsive receptors in the oral cavity. The purpose of this study was to determine the effects of mouth rinsing branched‐chain amino acids (BCAA) or CHO on cycle time trial performance, blood markers of central fatigue (prolactin), plasma insulin, glucose, and lactate concentrations, substrate oxidation during steady‐state exercise, and the subjective exercise experience. Ten healthy, endurance‐trained adult males (23.5 ± 3.8 y, 74.0 ± 9.0 kg, 180.5 ± 5.4 cm, 57.9 ± 6.9 ml/kg/min VO2 peak) volunteered for the study. Participants exercised at 65% Wattmax for 30 min then completed a time trial equivalent to 30 min cycling at 75% Wattmax. Participants rinsed the mouth with 6% glucose (CHO), 6% branched‐chain amino acids (BCAA), or water (PLA) for 10 s at the start and after every 10 min during the steady‐state exercise and cycle time trial. Treatment did not affect heart rate, ratings of perceived exertion, affect, arousal, plasma glucose and lactate concentrations, and substrate oxidation during steady‐state exercise and a cycle time trial. Furthermore, mouth rinsing BCAA or CHO did not affect plasma insulin or prolactin concentrations during steady‐state exercise or a cycle time trial. Finally, mouth rinsing BCAA or CHO did not affect cycle time trial performance after steady‐state exercise. In conclusion, mouth rinsing BCAA or CHO does not improve cycle time trial lasting approximately 30 min when performed after 30 min steady‐state exercise.

Maternal prolactin concentrations and lactational behaviour in the early postpartum period in women with lactational amenorrhoea

To compare early postpartum differences in maternal prolactin concentrations and lactational behaviour between women who have short and long periods of lactational amenorrhoea. Healthy lactating women resuming regular menstruation before 24 weeks [short amenorrhoea (SA) group; n = 15], and at or after 24 weeks [long amenorrhoea (LA) group; n = 15] postpartum were studied from 4 to 12 weeks postpartum. Infant feeding pattern and maternal plasma prolactin concentrations were compared between the two groups using repeated measures ANOVA. Breastfeeds/24 h were significantly higher and other feeds/24 h were significantly lower (p < 0.01) at 12 weeks postpartum in the LA group when expressed as a percentage of all feeds. Number of breastfeeds (total/24 h and night) significantly decreased and the number of other feeds significantly increased (p < 0.05 to 0 < 0.001) with time in both groups. Prolactin concentrations (basal, suckling stimulated and increment) were higher in the LA group, but consistent significant differences were observed mainly in the increment (p < 0.05 to p < 0.001). Prolactin concentrations significantly (p < 0.01 to < 0.001) decreased with time postpartum in the SA group, but not in the LA group. Women with longer periods of lactational amenorrhoea maintain higher prolactin concentrations than those with shorter periods of lactational amenorrhoea during the early postpartum period, even when the breastfeeding frequency is reduced. This could be explained by a greater sensitivity of the pituitary lactotrophe to the suckling stimulus in women who have longer periods of lactational amenorrhoea.

Hormone release, milk production and composition in Murrah buffaloes milked by hand and machine

Lactating Murrah buffaloes selected from the institute herd were categorized as hand and machine milking group. Blood samples were collected before milking, after concentrate feeding and teat message, during milking, and after completion of milking. Plasma prolactin (PRL), growth hormone (GH) and cortisol (CORT) concentrations were measured. Mean milk fat, protein, lactose and SNF content varied non-significantly between the groups. Milk somatic cell count (SCC), plasma glucose and NEFA concentration was more (P< 0.05) in machine milking group than in hand milking group. Both hand and machine milking operation significantly released plasma PRL (P< 0.01), CORT (P< 0.05) and GH (P< 0.01) hormone. Feeding of concentrate mixture resulted in a significant release in PRL and CORT hormone and their concentration increased further after teat message. Plasma PRL, CORT and GH varied significantly (P< 0.01) before, during and after milking (P< 0.01), and levels were normal 20-minutes post-milking in both the groups. It was concluded that feeding of concentrate mixture, teat message and milking operations either by hand or machine significantly stimulate release of plasma PRL, CORT and GH hormone in Murrah buffaloes.

Effect of sulpiride treatment during the periovulatory period on ovulation and LUF formation

The most common pathological anovulatory condition that occurs in the mare is the hemorrhagic anovulatory follicle (HAF). The exact cause is still unknown, but it is likely that many factors are involved in the inhibition of follicle rupture. The inhibition of prostaglandin synthesis by flunixin-meglumine during the periovulatory period resulted in a high percentage of luteinized unruptured follicles (LUF) in the mare [Cuervo-Arango et al., Theriogenology 2011; 76: 361-73]. High plasma prolactin (PRL) has been regarded as another possible cause of LUF. A recent study showed a 56% incidence on LUF development in mares with high PRL concentration after long term treatment with sulpiride [Zagrajczuk and Okolski, Reprod Dom Anim 2010;45(Suppl.3):62]. In vitro experiments have demonstrated that PRL during the periovulatory period inhibits ovulation by reducing ovarian plasmin generation in rabbits (Yoshimura et al., 1994). The aim of the present study was to determine the effect of sulpiride on ovulation during the periovulatory period in mares. Sixteen estrous cycles from 10 cyclic mares between February and June in Spain were randomly assigned to a control or sulpiride group (n1⁄48 each). All mares received 1500 IU of hCG (Hour 0) when they reached a follicular diameter 32 mm and presence of endometrial oedema. Mares were scanned every 12 h until ovulation or LUF formation. In the

Effects of hypothalamic dopamine (DA) on salsolinol (SAL)‐induced prolactin (PRL) secretion in male goats

The aim of the present study was to clarify the effects of hypothalamic dopamine (DA) on salsolinol (SAL)-induced prolactin (PRL) release in goats. The PRL-releasing response to an intravenous (i.v.) injection of SAL was examined after treatment with augmentation of central DA using carbidopa (carbi) and L-dopa in male goats under 8-h (8 h light, 16 h dark) or 16-h (16 h light, 8 h dark) photoperiod conditions. The carbi and L-dopa treatments reduced basal PRL concentrations in the 16-h photoperiod group (P < 0.05), while a reduction was not observed in the 8-h photoperiod group. The mean basal plasma PRL concentration in the control group for the 8-h photoperiod was lower than that for the 16-h photoperiod (P < 0.05). SAL significantly stimulated the release of PRL promptly after the injection in both the 8- and 16-h photoperiod groups (P < 0.05). PRL-releasing responses for the 16-h photoperiod were greater than those for the 8-h photoperiod (P < 0.05). The carbi and L-dopa treatments blunted SAL-induced PRL release in both the 8- and 16-h photoperiods (P < 0.05). These results indicate that hypothalamic DA blunts the SAL-induced release of PRL in male goats, regardless of the photoperiod, which suggests that both SAL and DA are involved in regulating the secretion of PRL in goats.

Chronic stress and its effects on adrenal cortex apoptosis in pregnant rats

The model of chronic intermittent stress by immobilization during pregnancy may produce alterations in the mechanisms that maintain adrenal gland homeostasis. In earlier investigations using this model, significant variations in plasma prolactin and corticosterone levels, and adrenal gland weights were observed. We hypothesized that chronic stress causes changes in apoptosis in the adrenal glands of pregnant rats. We identified and quantified apoptotic cells in the adrenal cortex and examined their ultrastructural characteristics using transmission electron microscopy. Adrenal glands of pregnant rats at gestation days 12, 17 and 21 were studied for control and experimental (stressed) rats. Immunolabelling techniques, stereological analysis and image quantification of adrenal gland sections were combined to determine differences in apoptosis in the different cell populations of the adrenal cortex. The apoptotic index of the experimental rats showed a significant reduction at gestation day 17, while at days 12 and 21 there were no differences from controls. Moreover, the apoptotic index of the reticular zones in control and experimental animals showed a significant increase compared to the glomerular and fascicular zones at the three gestation times studied. Chronic stress by immobilization reduced the caspase-dependent apoptotic index at gestation day 17, which may be related to variations in plasma concentrations of estrogens and prolactin.

Abstract A57: Alcohol consumption and plasma sex steroids in premenopausal women

Abstract Purpose: Alcohol consumption is a consistent risk factor for breast cancer, and evidence suggests premenopausal plasma hormones are associated with breast cancer. In this study, we examined the association between alcohol consumption and plasma sex steroid hormones in premenopausal women. Methods: We assessed the cross-sectional association between alcohol intake and circulating sex steroid concentrations among 2,034 premenopausal women in the Nurses' Health Study II (NHSII). Plasma concentrations of estradiol, estrone, estrone sulfate, testosterone, androstenedione, progesterone, prolactin, dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulphate (DHEAS) were measured in samples collected in 1996-99. Estrogens were measured in both the follicular and luteal phases of the menstrual cycle, while androgens were measured in the luteal phase as well as in random samples that were not timed in the menstrual cycle. Average alcohol intake was calculated from semi-quantitative food frequency questionnaires collected in 1995 and 1999. Results: Alcohol consumption was positively association with concentrations of luteal estrone (p-trend&amp;lt;0.0001) and luteal estradiol (p-trend=0.0001). Women who consumed more than 20 grams of alcohol per day, compared with non-drinkers, had higher concentrations of luteal estrone (geometric mean 98.0 vs. 79.9 pg/mL) and luteal estradiol (152.5 vs. 123.3 pg/mL). We did not observe statistically significant associations between alcohol and follicular estrogens, luteal estrone sulfate, testosterone, androstenedione, progesterone, prolactin, DHEA or DHEAS. Conclusion: Alcohol consumption was significantly positively associated with luteal estrogen concentrations, but not with plasma androgen levels, nor estrogens measured in the follicular phase. Thus, luteal estrogen levels may mediate the association between alcohol and breast cancer. Citation Format: Kelly A. Hirko, Susan E. Hankinson, A. Heather Eliassen. Alcohol consumption and plasma sex steroids in premenopausal women. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A57.

Nigerian bonny light crude oil induces endocrine disruption in male rats

Exposure to Nigerian bonny light crude oil (BLCO) in the southern part of Nigeria has been reported to be associated with reproductive toxicity, but there is paucity of information on its interference with steroidogenesis. This study investigated the influence of BLCO on testicular steroidogenesis and plasma levels of hormones from the pituitary and thyroid components of the brain–pituitary–testicular axis. Adult male Wistar rats were orally treated with BLCO dissolved in corn oil at 0, 200 and 800 mg/kg for 7 days. Immunoblot analysis revealed that BLCO exposure suppressed steroid acute regulatory protein and androgen-binding protein expression with concomitant decrease in 3β-hydroxysteroid dehydrogenase (HSD) and 17β-hydroxysteroid dehydrogenase activities. BLCO exposure significantly decreased plasma concentrations of follicle-stimulating hormone, luteinizing hormone, prolactin and intratesticular testosterone, but elevated thyrotropin, triiodothyronine and thyroxine above the control values. The data presented herein indicate that undue exposure to BLCO has an inhibitory effect on testicular steroidogenesis. The underlying mechanisms for BLCO-induced testicular dysfunction may involve its disruptive effect on the brain–pituitary–testicular axis. These observations highlight the potential risk to public health for a population where, unfortunately, oil spillages occur frequently.