Inactivation of Mycobacterium bovis ssp. caprae in high-temperature, short-term pasteurized pilot-plant milk.

Experiments to determine the efficacy of high temperature, short time (HTST) pasteurization of milk in terms of inactivation of pathogenic microorganisms were mainly performed between 1930 and 1960. Among the target organisms were Mycobacterium bovis and Mycobacterium tuberculosis. As a result, the Codex Alimentarius prescribes that HTST treatment of milk should lead to a significant reduction of pathogenic microorganisms during milk pasteurization. Due to the development of improved methods for the detection of survivors and of more advanced heating technology, verification of this requirement seemed to be necessary. To address recent outbreaks of tuberculosis in cattle caused by M. bovis ssp. caprae (M. caprae) in the southern regions of Germany, this organism was tested and compared with M. bovis ssp. bovis (M. bovis). Experiments were performed in a pilot plant for HTST pasteurization of milk with 3 strains of M. caprae and 1 strain of M. bovis. In preliminary trials at a fixed holding time of 25 s, the temperature at which significant inactivation occurred was 62.5°C for all strains. To determine D-values (decimal reduction times) for the inactivation kinetics, the strains were tested at 65, 62.5, and 60°C at holding times of 16.5, 25, and 35 s. At 65°C, the D-values of all strains ranged from 6.8 to 7.8 s, and at 62.5°C, D-values ranged from 14.5 to 18.1 s. Low inactivation was observed at 60°C. When the low slope of the inactivation curve allowed calculation of a D-value, these ranged from 40.8 to 129.9 s. In terms of log10 reductions, the highest values for all strains were 4.1 to 4.9 log at 65°C, with a holding time of 35 s. The tested strains of M. caprae and M. bovis showed similar low resistance to heat. Standard HTST treatment should result in a high reduction of these organisms and thus the requirements of the Codex Alimentarius for inactivation of pathogens by this process are far exceeded.

Soil texture and climate limit cultivation of the arsenic hyperaccumulator Pteris vittata for phytoextraction in a long-term field study.

Long term field studies are required to bridge gaps between research and practical application of arsenic phytoextraction with the arsenic-hyperaccumulating fern Pteris vittata. In a 4-year field study, we investigated the effects of nutrient application (compost, inorganic or organic nitrogen, inorganic or organic phosphorus) and soil texture (13 % and 35 % clay) on arsenic phytoextraction with P. vittata in moderately contaminated soils (74-79 mg As/kg in the 0-15 cm depth interval). We found the highest phytoextraction rates, 5 ± 1 kg As/ha/y, in a coarse-textured compost-amended soil after 2 years of phytoextraction. Phytoextraction rates decreased over time, likely due to decreased root growth in mature stands, indicating plants should be replaced every 2-3 years to maintain phytoextraction efficiency. Across soil textures, nitrogen or phosphorus application led to a 60 % decrease in mean frond arsenic concentrations, leading to mean phytoextraction rates 54 % lower than in control ferns. In the fine-textured soil, frond arsenic concentrations were 54 % lower than in the coarse-textured soil, and fewer ferns survived from year 3 to 4. Across soil textures, compost application increased fern survival. We show that phytoextraction with P. vittata is limited to specific soil and climate conditions, narrower than those under which P. vittata grows in the wild.

Arsenic hyperaccumulator Pteris vittata shows reduced biomass in soils with high arsenic and low nutrient availability, leading to increased arsenic leaching from soil.

Plant-soil interactions affect arsenic and nutrient availability in arsenic-contaminated soils, with implications for arsenic uptake and tolerance in plants, and leaching from soil. In 22-week column experiments, we grew the arsenic hyperaccumulating fern Pteris vittata in a coarse- and a medium-textured soil to determine the effects of phosphorus fertilization and mycorrhizal fungi inoculation on P. vittata arsenic uptake and arsenic leaching. We investigated soil arsenic speciation using synchrotron-based spectromicroscopy. Greater soil arsenic availability and lower nutrient content in the coarse-textured soil were associated with greater fern arsenic uptake, lower biomass (apparently a metabolic cost of tolerance), and arsenic leaching from soil, due to lower transpiration. P. vittata hyperaccumulated arsenic from coarse- but not medium-textured soil. Mass of plant-accumulated arsenic was 1.2 to 2.4 times greater, but aboveground biomass was 74% smaller, in ferns growing in coarse-textured soil. In the presence of ferns, mean arsenic loss by leaching was 195% greater from coarse- compared to the medium-textured soil, and lower across both soils compared to the absence of ferns. In the medium-textured soil arsenic concentrations in leachate were higher in the presence of ferns. Fern arsenic uptake was always greater than loss by leaching. Most arsenic (>66%) accumulated in P. vittata appeared of rhizosphere origin. In the medium-textured soil with more clay and higher nutrient content, successful iron scavenging increased arsenic release from soil for leaching, but transpiration curtailed leaching.

Conduction mechanism and switchable photovoltaic effect in (1 1 1) oriented BiFe0.95Mn0.05O3 thin film.

Epitaxial 200 nm BiFe0.95Mn0.05O3 (BFO) film was grown by pulsed laser deposition (PLD) on (1 1 1) oriented SrTiO3 substrate buffered with a 50 nm thick SrRuO3 electrode. The BFO thin film shows a rhombohedral structure and a large remnant polarization of Pr = 104 µC cm-2. By comparing I(V) characteristics with different conduction models we reveal the presence of both bulk limited Poole-Frenkel and Schottky interface mechanisms and each one dominates in a specific range of temperature. At room temperature (RT) and under 10 mW laser illumination, the as grown BFO film presents short-circuit current density (J sc) and open circuit voltage (V oc) of 2.25 mA cm-2 and -0.55 V respectively. This PV effect can be switched by applying positive voltage pulses higher than the coercive field. For low temperatures a large V oc value of about -4.5 V (-225 kV cm-1) is observed which suggests a bulk non-centrosymmetric origin of the PV response.

Histamine as a neuroendocrine regulator of the stress-induced release of peripheral catecholamines.

The involvement of hypothalamic histaminergic neurons in the stress-induced release of peripheral catecholamines was studied in conscious, freely moving male rats. Blood samples were obtained via a catheter in a femoral artery. Intracerebroventricular infusion of histamine (HA; 30 micrograms) increased the plasma concentrations of norepinephrine (NE) and epinephrine (E) 3- and 9-fold, respectively. The plasma level of dopamine was not affected. The effect of HA was prevented by prior intracerebroventricular infusion of the H1-receptor antagonist mepyramine (100 micrograms) or the H2-receptor antagonist cimetidine (100 micrograms). Restraint stress applied for 5 min caused an immediate but transient increase in the plasma concentrations of NE and E which were increased 5- and 11-fold, respectively. The plasma level of dopamine was not altered significantly by restraint stress. The effect of stress on NE and E was almost prevented by prior icv infusion of mepyramine or cimetidine. The HA receptor antagonists had no effect on the basal plasma catecholamine level. We conclude that neuronal HA is an important mediator of the restraint stress-induced release of peripheral catecholamines by an action on H1- and H2-receptors within the central nervous system.

Semiautomated quantitative detection of loss of heterozygosity in the tumor suppressor gene p53.

The most frequently altered gene in diverse tumor types is the tumor suppressor gene p53. Typically, normal function is inactivated by point mutation of one allele and deletion of the other. Therefore, loss of heterozygosity (LOH) of intragenic polymorphic markers is a strong indication for p53 involvement in a cancerous lesion. This study shows that a highly polymorphic short tandem repeat (STR) within intron 1 of p53 is an excellent marker for quantitative evaluation of LOH in tumor samples, whose multicolor, fluorescently tagged PCR products are analyzed and quantitated on an automated DNA sequencer. The range of error was analyzed in detail. Discrete allelic profiles were obtained following amplification of DNA from microdissected cell samples of patients with urogenital tumors. By calculating qLOH, the relative allele ratio of a tumor compared with healthy tissue, a quantitative expression for the LOH is obtained. PCR-based tumor DNA typing using fluorescent STR primers and automated analysis provides an enhanced level of accuracy and sensitivity required for routine analysis in clinical practice, where large numbers of tumor samples have to be processed.

Beta-adrenergic receptors are involved in histamine-induced secretion of proopiomelanocortin-derived peptides and prolactin in rats.

The neurotransmitter histamine (HA) is involved in central regulation of secretion of prolactin (PRL) and the proopiomelanocortin (POMC)-derived peptides adrenocorticotropin (ACTH), beta-endorphin (beta-END) and alpha-melanocyte-stimulating hormone (alpha-MSH). The effect of HA on POMC-derived peptides and PRL release is, at least in part, indirect and may involve activation of catecholaminergic systems. Therefore, we investigated the effect of beta-adrenergic receptor blockade on HA or HA agonist-induced release of ACTH, beta-END, alpha-MSH and PRL. Central administration of HA, the H1-receptor agonist 2-thiazolylethylamine (2-TEA) or the H2-receptor agonist 4-methylhistamine (4-MeHA) stimulated the secretion of ACTH, beta-END, alpha-MSH and PRL. Pretreatment with the beta-adrenergic antagonist propranolol inhibited secretion of the POMC peptides in response to HA, 2-TEA or 4-MeHA. Propranonol only inhibited the PRL response to HA or 2-TEA, but had no effect on the PRL response to 4-MeHA. Administration of the beta-receptor agonist isoproterenol stimulated ACTH, beta-END, alpha-MSH and PRL two to five-fold. This effect was totally blocked by pretreatment with propranolol. We conclude that HA-induced secretion of POMC-derived peptides from the anterior and intermediate lobe of the pituitary gland and of PRL from the anterior lobe is, at least in part, mediated via catecholamines. beta-Adrenergic receptors are involved in the mediation of the POMC response to H1- as well as H2-receptor activation, whereas beta-receptors are involved only in the mediation of the PRL response to H1-receptor activation.

Increased UV-induced sister-chromatid exchange in cultured fibroblasts of first-degree relatives of melanoma patients.

Cultured fibroblasts of 17 first-degree relatives of familial melanoma patients and six first-degree relatives of cutaneous melanoma (CMM) patients with multiple CMM primaries were tested for in vitro sensitivity to UV light. Fibroblasts of nine familial CMM patients with a known UV-sensitivity and 19 healthy probands served as a control. Sister chromatid exchange (SCE) was used as a parameter to detect UV-induced genotoxic damage. We found significantly (p less than 0.001) increased UV-induced SCE levels in familial melanoma patients, as well as in first-degree relatives of familial melanoma patients (p less than 0.001) after UV-A,B irradiation (375 J/m2), compared to the healthy probands without a family history of CMM. A significant (p less than 0.001) increase of UV-induced SCE was also observed in the relatives of CMM patients with multiple CMM primaries. In addition, the spontaneous SCE were significantly increased (p less than 0.05) in familial CMM patients. This study shows that increased UV sensitivity is a familial phenomenon. It is consistent with the concept of a genetic predisposition to CMM, which is based on increased UV sensitivity and may help to define groups with an elevated risk of developing cutaneous malignant melanoma.

Natural killer cell activity during head-up tilt-induced central hypovolemia in humans.

Changes in immunological competent blood cells were evoked in seven humans during passive head-up tilt (50 degrees anti-Trendelenburg's position maintained until appearance of presyncopal symptoms). Blood samples were collected after 60 min of rest, when presyncopal symptoms appeared during tilt, and 105 min after tilt-down. Natural killer (NK) cell activity increased during head-up tilt due to a three to four-fold increase in CD16+ NK cells in blood. In support NK cell activity boosted with interferon-alpha and interleukin 2 (IL-2) rose in parallel with unboosted NK cell activity. This effect on NK cells disappeared during recovery but was not suppressed when compared to prevalues. Lymphocyte concentration also increased during head-up tilt. Concentrations of CD3+ and CD4+ T cells were almost stable during head-up tilt, whereas the percentage of CD3+ T cells in relation to blood mononuclear cell (BMNC) concentration decreased, due to a diminished percentage of CD4+ T cells and the marked simultaneous increase in the percentage of CD16+ NK cells. Although changes in the BMNC composition occurred, the proliferative responses of BMNC following stimulation with phytohemagglutinin, purified derivative of tuberculin, or IL-2 did not change significantly. We conclude that head-up tilt induced marked changes in subpopulations of BMNC, especially the CD16+ NK cells, as they were recruited to the blood.

Tolerance to head-up tilt and suspension with elevated legs.

OBJECTIVE: Orthostatic hypotension is usually a benign event. However, some patients are disabled by frequent syncopal events, and vertical transportation during helicopter rescue, for example, may even be fatal. Normal orthostatic tolerance is poorly defined, so we evaluated the response to 50 degrees head-up tilt. Also, the effect of leg elevation was examined in order to establish the influence of venous return, and a fatal accident associated with orthostasis is reported. METHODS: There were 79 volunteers who were subjected to 50 degrees head-up tilt, and 9 subjects performed 1 h of suspension by double strops placed around the thorax and knee bends, respectively. The time to presyncope and changes in BP, heart rate, thoracic electrical impedance, central venous pressure and central venous and muscle oxygen saturations were measured. RESULTS: Head-up tilt resulted in hypotension, bradycardia and presyncopal symptoms in 69 subjects within 1 h (87%; half time 27 min), but during suspension with elevated legs in only one subject (11%; p < 0.02). In presyncopal subjects the central blood volume was reduced as reflected by an elevated thoracic electrical impedance and reduced central venous and muscle oxygen saturations. CONCLUSIONS: During 50 degrees head-up tilt, half of 79 subjects near-fainted within 27 min, whereas elevation of the legs secured venous return to the heart and prevented presyncopal symptoms. The high rate of near-fainting in normal subjects should be taken into account during evaluation of patients with syncope, and it emphasizes the use of a position that secures venous return during transportation.

Neovaginal construction in vaginal aplasia and sex-reassignment surgery.

During the period 1984-1994 33 patients were admitted to the department of plastic surgery for the purpose of neovaginal construction. They comprised 22 patients with vaginal agenesis or aplasia and 11 transsexual men. In most cases neovaginal construction was done by blunt dissection and lining with a split thickness skin graft from the thigh, and in the cases of sex-reassignment surgery genital skin was also used. The two groups differed as the patients with vaginal agenesis or aplasia had remarkably few complications compared with the transsexual group. The most common complications were defects in the skin grafts and vaginal stenosis. The transsexuals therefore had an extended recovery period including several admissions and visits to the outpatient clinic. The difference in genotype does not explain the high complication rate in the transsexual group as eight in the vaginal agenesis or aplasia group had Morris syndrome (testicular feminisation (XY)). However, the phenotype may be of importance in vaginal construction as the male (transsexual) pelvis is narrow and the levator muscles are stronger than those in the female pelvis.

A new amorphous hydrocolloid for the treatment of pressure sores: a randomised controlled study.

A randomised controlled study was carried out to compare the effect of a new amorphous hydrocolloid (hydrogel, Coloplast) with that of conventional treatment on the healing time of pressure sores. After initial debridement in the outpatient clinic of pressure sores located in the sacral (n = 21) or trochanteric (n = 11) area the patients were randomised to be treated with either hydrogel (n = 17) or wet saline compresses (n = 15). Once a week the healing was estimated by the same investigator. The relative volumes (from the initial 100%) of hydrogel-treated wounds were significantly less (26 +/- 20%, p < 0.02) than those of saline treated wounds (64 +/- 16%) in the last week of the study. The saline treated wounds needed more frequent weekly debridement than the hydrogel-treated wounds (21% compared with 7% of all weekly dressings, p < 0.03). We conclude that amorphous hydrocolloid increases current healing of pressure sores compared with conventional treatment. It is therefore a better choice for treating patients with pressure sores in their homes.

[Idiopathic aortoduodenal fistula]. / Idiopatisk aortoduodenal fistel.

A case of primary aortoduodenal fistula of unknown origin in a 72 year old female is presented. The fistula was successfully treated by excision from the duodenum and direct suture of the aortic wall.

[Incidence and treatment of urinary calculi in patients in Frederiksborg County]. / Forekomst og behandling af sten i urinveje hos patienter i Frederiksborg Amt.

The case records of all patients admitted to one of the hospitals in the County of Frederiksborg with radiologically demonstrated first episodes of urinary calculi during a period of one year in 1983/1984 and 1988/1989 respectively were reviewed retrospectively. Uniform frequencies of calculus incidence and sex distribution were encountered mutually and as compared with the remainder of Denmark during the two periods. In 30% of the cases the calculi were localized to the kidneys and in 58% to the ureter. In approximately 65% of the patients, the greatest diameter of the stones was 100 mm or less. Spontaneous passage of the stones occurred in approximately 40%. Development in the treatment of urinary tract stones has followed the development in the county as a whole. The number of operative interventions during the five year period was reduced by 30% and extracorporeal shock wave treatment was employed in 22% during the second period.

Super switching and control of in-plane ferroelectric nanodomains in strained thin films.

With shrinking device sizes, controlling domain formation in nanoferroelectrics becomes crucial. Periodic nanodomains that self-organize into so-called 'superdomains' have been recently observed, mainly at crystal edges or in laterally confined nanoobjects. Here we show that in extended, strain-engineered thin films, superdomains with purely in-plane polarization form to mimic the single-domain ground state, a new insight that allows a priori design of these hierarchical domain architectures. Importantly, superdomains behave like strain-neutral entities whose resultant polarization can be reversibly switched by 90°, offering promising perspectives for novel device geometries.

Studies of injection ports of permanent expandable breast implants.

It has previously been questioned if the injection port of soft-tissue expanders is a source of leakage. However, several laboratory studies have concluded that the port is safe. A former quality assessment of our one-stage breast reconstructive procedures showed, that suspicion of leakage led to the removal of the injection port in 12% of the cases. With this level of inconsistency with previous laboratory studies, we found a need to conduct a separate study in order to confirm the true cause of leakage. Thirteen consecutively removed McGhan Style 150 injection ports were examined for leakage by increasing intraluminal pressure. Eight of the 13 ports had been removed because of discomfort due to the subcutaneous placement. Three of these eight ports showed substantial leakage (up to 14.55 ml/hour) at pressures attainable under normal in vivo circumstances. Five of the 13 ports had been removed due to clinical leakage. All five showed substantial leakage in the experimental setting (up to 19.65 ml/hour). Comparing the placement of the leaking puncture holes with the construction of the port, it seems that the leaking puncture holes are the result of peripheral perforations escaping the self-sealing material in the port, while still allowing injection of saline. The study shows clinical and experimental evidence of leakage from the McGhan Style 150 injection port, which is contrary to other similar laboratory studies. However, in those studies the needles were inserted at the apex of the port membrane, while our study shows that this is not in accordance with a clinical setting, where perforation may be all over the port. It is concluded that extreme care should be taken in the clinical setting only to perpendicularly perforate the apex of the injection port membrane. Peripheral perforation of the port may result in leakage of saline.

Neuroendocrine mechanisms during reversible hypovolaemic shock in humans with emphasis on the histaminergic and serotonergic system.

In humans, the head-up tilted position results in central hypovolaemia which mimicks haemorrhage and is associated with cardiovascular changes that can be divided into two stages. 1) One stage with increase in HR and vascular resistance and a slight increase in MAP. 2) Another stage with decrease in HR, vascular resistance and MAP and appearance of presyncopal symptoms (hypovolaemic shock). The first stage is "sympathoexcitatory" as plasma NA originating from postganglionic vasoconstrictory sympathetic neurons increase. Limb vascular resistance contributes to the increase in TPR at this time. The second stage is "sympathoinhibitory" in nature as plasma NA slightly decreases, or remains unchanged, while plasma A, originating from the adrenal medulla, raises. This pattern is a reflection of a differentiated sympathetic response as an increase in the activity of the nerves innervating the adrenals and decrease in renal sympathetic nerves has been reported by others. There is a decrease in limb as well as total vascular resistance. The secretion of potent vasoactive peptides may contribute to the circulatory changes taken place during head-up tilt. The head-up tilted position is associated with central hypovolaemia which is reliably monitored by electrical impedance. There is a close relation between the increase in thoracic electrical impedance and the decrease in plasma ANP which is regulated by atrial stretch. Also, from recording of technetium labeled red blood cells and measurements of haematocrite the decrease in CBV is reflected by thoracic electrical impedance. In contrast, CVP reflects changes in CBV during the initial head-up tilt only, whereafter CVP usually is unchanged or may even increase. After the initial head-up tilt the decrease in the CBV is caused by further reduction in plasma volume as shown by increase in haematocrite and unchanged distribution of labeled red blood cells. This mechanism is reflected by application of regional electrical impedance measurements at a low and high frequency current. The low frequency current, passing extracellular fluid only, changing more than the high frequency current that passes extra as well as intracellular fluid. Central hypovolaemia was found to stimulate the pituitary-adrenal axis, and the development of hypotension strongly increases plasma ACTH, beta-END, cortisol and PRL. Blocking histaminergic receptors did not change the pituitary-adrenal response to central hypovolaemia, while the sympathoadrenal response was affected by histaminergic receptor blockade. The H2-receptor antagonist cimetidine inhibited plasma A, while the H1-receptor antagonist mepyramine attenuated plasma NA and reduced cardiovascular tolerance, and also induced some sedation. A possible effect of sedation and anxiolysis was investigated by administration of the GABAergic drug diazepam. This drug did not change the cardiovascular response to head-up tilt, but reduced the increase in plasma cortisol. This indicates that the appearance of presyncopal symptoms is not related to "stress" but associated with the cardiovascular effects of central hypovolaemia. Another endogenous substance, serotonin (5-HT), may be also involved in cardiovascular as well as endocrine regulation. We investigated the effect of blocking three main receptors on the development and effects of hypovolaemic shock. Methysergide (5-Ht1+2-receptor antagonist) attenuated plasma NA, beta-END, PRL and PRA during tilt with a slight reduction of cardiovascular tolerance. The 5-HT2-receptor antagonist ketanserin reduced cardiovascular tolerance without significant effects on the hormonal responses. The 5-HT3-receptor antagonist ondansetron inhibited the plasma CGRP and adrenalin response to central hypovolaemia without influencing cardiovascular tolerance. It is concluded that the head-up tilted model in humans can be applied to study cardiovascular and endocrine mechanisms until the development of hypovolaemic shock.(ABSTRACT TRUNCATED)

Cardioinhibitory-vasodepressor response to head-up tilt without hypoxaemia or myocardial ischaemia.

We evaluated whether hypoxaemia and/or myocardial ischaemia are of importance for development of the bradycardic hypotensive phase (cardioinhibitory-vasodepressor syncope) of central hypovolaemia. Arterial blood gas variables and a twelve-lead electrocardiogram (ECG) were followed during head-up tilt in seven men. During tilt, before presyncopal symptoms appeared, mean arterial pressure (MAP) increased (from 67 +/- 7 to 78 +/- 6 mmHg) (mean +/- SE) as did heart rate (HR) (61 +/- 4 to 99 +/- 8 beats min-1) and total peripheral resistance (TPR) (11 +/- 1 to 17 +/- 1 mmHg min l-1) (P < 0.01), while cardiac output (5.9 +/- 0.5 to 4.6 +/- 0.6 l min-1) and central venous pressure (CVP) (4.2 +/- 0.4 to 1.3 +/- 0.7 mmHg) decreased (P < 0.01). After 40 +/- 7 min of head-up tilt presyncopal symptoms appeared together with a decrease in MAP to 48 +/- 7 mmHg, HR to 71 +/- 11 beats min-1 and TPR to 9 +/- 2 mmHg min l-1 (P < 0.01). Arterial oxygen tension was not changed and there was no ST-segment depression of the ECG. The results indicate that during central hypovolaemia decreases in HR and TPR are elicited during normoxaemia and without electrocardiographic signs of myocardial ischaemia.

Effect of anaesthetics on PRL and LH secretion in rats. Importance of pre-anaesthetic adaptation and involvement of monoaminergic neurons.

General anaesthesia has been reported to interact with neuroendocrine functions leading to large variations in basal and stimulated plasma levels of several hormones, but the findings are often contradictory. In the present investigation we have attempted to clarify the importance of the experimental procedure when evaluating the influence of anaesthetics on the secretion of PRL and LH in male rats. One group of rats (non-adapted) were anaesthetized (ip) with pentobarbital (P), urethane (U), ketamine (A), or althesin (A) without being accustomed to the laboratory environment prior to anaesthesia. Another group of rats (adapted) were kept for 90 min in their individual cages before induction of anaesthesia with P or U. In non-adapted rats the plasma concentration of PRL declined rapidly during the first 30 min following administration of all anaesthetics or saline (controls) and attained a steady level after 60 min. Except for a brief rise following U injection, the LH concentration was not affected by anaesthesia in the non-adapted rats. In adapted rats, the concentration of both PRL and LH declined markedly during the pre-anaesthetic adaptation period and had stabilized at the end of that period. Following administration of U, P or saline, no further changes in the hormone concentrations were observed. Injection of the dopamine receptor antagonist pimozide prevented the decrease in plasma PRL during the adaptation period, but had no effect on LH secretion. In pimozide-treated rats, U caused a 5-fold increase in the PRL concentration. This effect of U was inhibited by the serotonin receptor antagonist methysergide. The PRL response to 30 micrograms of histamine was similar in conscious and U-anaesthetized rats, whereas P anaesthesia caused a reduction in the response.(ABSTRACT TRUNCATED AT 250 WORDS)

Histaminergic mediation of the stress-induced release of prolactin in male rats.

Histamine (HA) is likely to participate in the neuroendocrine regulation of prolactin (PRL) secretion. We, therefore, studied the possible involvement of HA in the stress-induced release of PRL in conscious male rats. HA (30 micrograms) infused intracerebroventricularly 15 min before decapitation elevated PRL plasma levels from 5 +/- 1 to 54 +/- 6 ng/ml (p less than 0.01). Intracerebroventricular infusion of the H2 receptor antagonists cimetidine (CIM: 100 micrograms) or ranitidine (RAN: 125 micrograms) abolished the PRL response to HA (p less than 0.01), while intracerebroventricular infusion of the H1 receptor antagonist mepyramine (MEP; 100 micrograms) inhibited the response only 40% (p less than 0.05). Intra-arterial infusion of CIM (2,000 micrograms) or RAN (2,500 micrograms) inhibited the HA-stimulated PRL secretion 52% (p less than 0.01) or 63% (p less than 0.01), respectively. The H1 receptor antagonists MEP (1,000 micrograms) and SKF-93944 (1,500 micrograms) had no effect following intra-arterial administration. Restraint stress increased the PRL level to 84 +/- 6 ng/ml (p less than 0.01 vs. control). This effect was prevented by intracerebroventricular infusion of CIM or RAN (p less than 0.01) and inhibited 75% by MEP (p less than 0.01). Intra-arterial infusion of CIM, MEP, and SKF-93944 inhibited the stress response about 50% (p less than 0.01), while RAN decreased the response only 25% (p less than 0.05). Ether stress elevated the plasma PRL concentration to 46 +/- 5 ng/ml (p less than 0.01 vs. control). When infused intracerebroventricularly CIM or RAN prevented the response (p less than 0.01), while MEP had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)