Exercise in claudicants is accompanied by excessive thrombin generation

BACKGROUND

exercise in IC leads to ischaemia-reperfusion injury of leg muscles and a systemic inflammatory response, but the effect of on coagulation is unknown.

OBJECTIVE

to compare the effect of exercise on thrombin formation and fibrin turnover in patients with IC (n = 10), and age and sex matched smokers ([S] n = 5) and non-smokers ([NS] n = 5) without peripheral vascular disease.

METHODS

blood was taken from subjects 60 and 30 min before, and 1, 5, 20, 40, 60 and 120 min after, treadmill exercise. Markers of thrombin generation (thrombin-antithrombin complexes [TAT] and prothrombin fragments 1 + 2 [PF1 + 2]) and fibrin turnover (D-dimer and fibrin degradation products [FbDP]) were assayed at each time point.

RESULTS

following exercise, thrombin generation was significantly greater in the claudicant group compared to the control groups (Area Under Curve [AUC] post exercise IC vs S vs NS; TAT 3960 vs 1623 vs 1476 vs = 0.007 Kruskal-Wallis [KW]; PF1 + 2 163 vs 107 vs 123 p = 0.024 KW). Pre and post-exercise, fibrin turnover in claudicants was similar to smoking controls, but higher than non-smoking controls. (AUC post exercise IC vs NS; D-dimer 6340 vs 2754 p = 0.055 Mann-Whitney U[MW]; FbDP 45113 vs 21511 p = 0.009 MW).

CONCLUSION

when compared to non-claudicants, exercise in IC is associated with excessive production of thrombin. Despite this, claudicants have a similar level of fibrin turnover suggesting a possible defect in fibrinolysis. This prothrombotic state may contribute to the excess thrombotic morbidity and mortality suffered by claudicants.

Leptin reduces food intake but does not alter weight regain following food deprivation in the rat

OBJECTIVE

When animals are allowed free access to food following an extended period of food restriction, body weight is steadily restored to the pre-food restriction level, ie to a specific body weight 'set-point'. We tested the proposition that leptin is used as a signal by the brain to regulate body weight 'set-point'. To this end, we determined whether long-term leptin infusion in rats would prevent the normal weight regain after food restriction.

METHODS

Male Sprague-Dawley rats received leptin (leptin-treated) or saline (vehicle-treated) by intravenous infusion. After a 2 week run-in period, food intake was adjusted to 50% of each individual's normal intake for 12 days. Two days prior to the return of unlimited access to food, one group of animals received continuous leptin infusion at 3 micro g/h for the next 14 days. Blood samples taken from the tail vein were used to determine leptin concentrations. A third group of animals that did not undergo food restriction but received saline infusion served as control. As leptin acts in the brain to modulate neuropeptide Y (NPY) levels, hypothalamic NPY content was measured at the end of the study.

RESULTS

Food restriction to 50% normal intake for 12 days induced a 20% weight loss and significant reductions in plasma leptin compared with non-restricted control rats (0.5+/-0.1 vs 2.6+/-0.4 ng/ml, P<0.05). Intravenous infusion of leptin increased leptin concentrations four-fold compared with vehicle-treated animals (9.5+/-1.3 vs 2.2+/-0.4 ng/ml, P<0.05). The infusion of leptin attenuated the increase in daily food intake after free access to food was resumed (P<0.05 at 4, 6 and 8 days). Despite this, both groups of previously restricted rats had regained the same amount of weight after 12 days of ad libitum feeding. No difference was noted in NPY levels measured in the arcuate nucleus and the paraventricular nucleus, in line with the similar amounts of food eaten by all rats at the end of the experiment.

CONCLUSION

Increasing plasma leptin concentrations just prior to the end of a period of food restriction reduced subsequent food intake, but did not appear to exert a major influence on the body weight 'set-point', as leptin did not prevent weight regain. The results of the present study suggest that leptin may be of little value in maintaining weight loss in individuals who have lost weight through dieting. Further research is required to understand the role of leptin in the regulation of energy balance.

Association between hyperhomocysteinaemia and abdominal aortic aneurysm

Background

Hyperhomocysteinaemia is associated with occlusive vascular disease. In vitro evidence has demonstrated the induction of a serine elastase by homocysteine in vascular smooth muscle. Anecdotal evidence from case reports and post-mortem studies has suggested an association with abdominal aortic aneurysm (AAA). The aim was to determine the prevalence of hyperhomocysteinaemia in patients with AAA.

Methods

Some 120 subjects (60 controls and 60 patients with AAA) were studied prospectively. Epidemiological, clinical and haematological data were collected. Patients were defined as having AAA if ultrasonographic measurement of the aorta was greater than 4·5 cm. Those with evidence of occlusive peripheral vascular disease or an ankle: brachial pressure index lower than 0·8 were excluded. Homocysteine was measured with a commercial high-pressure liquid chromatography analyser. The reference range from age-matched controls was 8·9–14·3 µmol l−1.

Results

The median(s.d.) value of homocysteine for patients was significantly higher than that for the control group: 13·1(7·88) versus 10·9(5·07) µmol l−1 (P = 0·03, Mann–Whitney U test). Hyperhomocysteinaemia (homocysteine concentration greater than 14·3 µu;mol l−1) was present in 48 per cent of patients with AAA, compared with 24 per cent of the control population (P &lt; 0·01, χ2 test). There were no significant differences between groups with regard to age, folate levels, vitamin B12 concentration or renal function.

Conclusion

These results strongly suggest an association between hyperhomocysteinaemia and AAA. If studies currently ongoing demonstrate a causal relationship between hyperhomocysteinaemia and vascular disease progression, it raises the possibility of treating small aneurysms with vitamin supplementation to slow their growth.

Second best medical therapy

BACKGROUND

Best medical therapy (BMT) provides patients with peripheral arterial disease (PAD) substantial protection against future vascular events.

OBJECTIVE

To determine the quality of BMT received by PAD patients in this vascular surgery unit.

METHODS

Retrospective case-note review of 50 consecutive patients in each of the following groups: intermittent claudication (out-patients), symptomatic carotid artery disease (out-patients), lower limb angioplasty, lower limb bypass surgery, carotid endarterectomy.

RESULTS

Overall BMT use was poor. Fifteen percent of smokers had assistance with smoking cessation noted. Seventy-eight percent of patients were taking an antiplatelet agent, 38% cholesterol-lowering medication and 51% antihypertensive medication. Fifty-three percent of patients had a cholesterol measurement, 50% of out-patients had a blood pressure measurement and 53% of non-diabetics had a random blood glucose performed. Sixteen of the patients with lower limb disease were given advice about exercise. Patients with a history of coronary artery disease were more likely to be taking cholesterol lowering, or antihypertensive medication.

CONCLUSIONS

BMT is poorly used in patients with PAD, which will result in an excess of cardiovascular morbidity and mortality. Strategies need to be developed to increase the use of BMT in our patients.

Prophylaxis of radiation-associated mucositis in conventionally treated patients with head and neck cancer: a double-blind, phase III, randomized, controlled trial evaluating the clinical efficacy of an antimicrobial lozenge using a validated mucositis scoring system

PURPOSE

Mucositis occurs in almost all patients treated with radiotherapy for head and neck cancer. The aim of this multicenter, double-blind, prospective, randomized trial was to evaluate the clinical efficacy of an economically viable antimicrobial lozenge (bacitracin, clotrimazole, and gentamicin [BcoG]) in the alleviation of radiation-induced mucositis in patients with head and neck cancer.

PATIENTS AND METHODS

One hundred thirty-seven eligible patients were randomized to treatment with either antimicrobial lozenge (69 patients) or placebo lozenge (68 patients). The primary end point of the study was the time to development of severe mucositis from the start of radiotherapy. Secondary end points included severity and duration of mucositis, pain measurement, radiation therapy interruption, and quality of life. Mucositis was scored using a validated mucositis scoring system.

RESULTS

Toxicity profiles were similar between the two arms of the study. The median time to development of severe mucositis from the start of radiotherapy was 3.61 weeks on BCoG and 3.96 weeks on placebo (P =.61). There were no statistically significant differences between the arms in the extent of severe mucositis as measured by physician, in oral toxicities as recorded by patients, or in radiotherapy delays.

CONCLUSION

This study was conducted on the basis of a pilot study that demonstrated the BCoG lozenge to be tolerable and microbiologically efficacious. A validated mucositis scoring system was used. However, in this group of patients treated with conventional radiotherapy, the lozenge did not impact significantly on the severity of mucositis. Whether such a lozenge would be beneficial in treatment situations where rate of severe mucositis is higher (ie, in patients treated with unconventional fractionation or with concomitant chemotherapy) is unknown.

Thrombophilia and chronic venous ulceration

It is known that thrombophilia (TP) is a risk factor for deep venous thrombosis (DVT), and that DVT predisposes to chronic venous ulceration (CVU). However, the relationship between TP and CVU has not been well studied. Review of the literature reveals that the prevalence of TP in CVU patients is high--similar to the prevalence found in patients with a history of DVT. This is despite many patients with CVU having no clear history, or duplex evidence of previous DVT. TP may predispose to CVU by leading to macro- or micro-vascular thrombosis. This association raises several issues regarding the investigation, prevention and management of patients with venous disease.

What constitutes best medical therapy for peripheral arterial disease?

Peripheral arterial disease (PAD) is associated with a high morbidity and mortality, largely from coronary and cerebrovascular disease, which often overshadows the PAD itself. Best Medical Therapy (BMT), comprising smoking cessation, antiplatelet agent use, cholesterol reduction, exercise therapy, and the diagnosis and treatment of hypertension and diabetes mellitus; is evidenced based and can result in significant reductions in cardiovascular risk, as well as some improvement in PAD. Previous data have largely been restricted to patients with coronary artery disease, and their relevance to PAD has been extrapolated. However, data are now starting to become available, such as the Heart Protection Study, with data specific to PAD patients. This article reviews the data regarding the use of BMT in patients with PAD, and based on this, makes recommendations for the use of BMT in this group of patients.

Circulating relaxin acts on subfornical organ neurons to stimulate water drinking in the rat

Relaxin, a peptide hormone secreted by the corpus luteum during pregnancy, exerts actions on reproductive tissues such as the pubic symphysis, uterus, and cervix. It may also influence body fluid balance by actions on the brain to stimulate thirst and vasopressin secretion. We mapped the sites in the brain that are activated by i.v. infusion of a dipsogenic dose of relaxin (25 microg/h) by immunohistochemically detecting Fos expression. Relaxin administration resulted in increased Fos expression in the subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT), median preoptic nucleus, and magnocellular neurons in the supraoptic and paraventricular nuclei. Ablation of the SFO abolished relaxin-induced water drinking, but did not prevent increased Fos expression in the OVLT, supraoptic or paraventricular nuclei. Although ablation of the OVLT did not inhibit relaxin-induced drinking, it did cause a large reduction in Fos expression in the supraoptic nucleus and posterior magnocellular subdivision of the paraventricular nucleus. In vitro single-unit recording of electrical activity of neurons in isolated slices of the SFO showed that relaxin (10(-7) M) added to the perfusion medium caused marked and prolonged increase in neuronal activity. Most of these neurons also responded to 10(-7) M angiotensin II. The data indicate that blood-borne relaxin can directly stimulate neurons in the SFO to initiate water drinking. It is likely that circulating relaxin also stimulates neurons in the OVLT that influence vasopressin secretion. These two circumventricular organs that lack a blood-brain barrier may have regulatory influences on fluid balance during pregnancy in rats.

A meta-analysis of the use of typical antipsychotic agents in bipolar disorder

BACKGROUND

The potential benefits of typical antipsychotic agents in bipolar disorder are offset by serious treatment-associated side effects. Despite these concerns and the availability of mood stabilizing agents, the treatment of bipolar disorder with typical antipsychotic agents appears to be widespread.

METHODS

A Medline search identified 16 publications that outlined medication use among 2378 bipolar disorder patients. Meta-analysis was used to estimate a weighted average of the relative proportions of the treatment use, where the weights were the reciprocals of the estimated variances for each study.

RESULTS

Overall, 84.7% of bipolar patients received typical antipsychotic agents, with a loading toward a greater in-patient (90.7%) relative to out-patient (65.3%) use. Monotherapy accounted for 53.8% of typical antipsychotic use, and typical antipsychotic/mood stabilizer combination therapy accounted for 47.4%. In four studies where length of treatment data were available, the median of minimum typical antipsychotic use was 2.5 months, with 96.0% of the patients receiving typical antipsychotic agents.

LIMITATIONS

The meta-analytic technique employed in this analysis is limited by the possible inclusion of studies with unreliable study designs or biased treatment practices, publication bias in which some studies may not have been reported, and possible lack of identification of all relevant studies.

CONCLUSIONS

Typical antipsychotic agents are commonly used in the treatment of bipolar disorder, possibly due to dissatisfaction with mood stabilizer monotherapy especially in psychotic mania, the high prevalence of psychotic symptoms in acute mania, inappropriate continuation of typical antipsychotic agents after initial stabilization, and/or unavailability or unfamiliarity with new treatments. These findings also suggest that typical antipsychotics may have not only antipsychotic effects in mania but perhaps also antimanic properties.

Cerebral Na concentration, Na appetite and thirst of sheep: influence of somatostatin and losartan

Na and water intakes of Na-depleted sheep are influenced by changes in cerebral Na concentration. The effect of intracerebroventricular infusion of somatostatin or losartan, the ANG II type 1 receptor antagonist, on the Na appetite and thirst of Na-depleted sheep during infusions that decrease (intracerebroventricular hypertonic mannitol) or increase (intracerebroventricular or systemic hypertonic NaCl) cerebral Na concentration was investigated. Na intake was increased but water intake was unchanged during intracerebroventricular infusion of hypertonic mannitol. The increased Na appetite caused by intracerebroventricular infusion of hypertonic mannitol was decreased by concurrent intracerebroventricular infusion of either somatostatin or losartan, with somatostatin being most effective. Water intake was increased during intracerebroventricular infusion of hypertonic mannitol and somatostatin. Na intake was decreased and water intake was increased during systemic or intracerebroventricular infusion of hypertonic NaCl. Intracerebroventricular infusion of losartan blocked both (Na and water intake), whereas somatostatin did not influence either of these changes in intake. The results further consolidate a role for somatostatin and ANG II in the central mechanisms controlling Na appetite and thirst of sheep.

An fMRI study of stimulus equivalence

In order to study brain activation during the formation of equivalence relations, 12 subjects underwent fMRI during matching-to-sample (MTS) tests of (1) previously trained arbitrary relationships between iconic stimuli and the untrained, emergent relations of (2) symmetry, (3) transitivity, and (4) symmetry with transitivity, plus a test of verbal fluency (VF). Brain activation was similar in all MTS tasks and in the VF task. In particular, both types of task activated dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex bilaterally. However VF, but not the MTS tasks, activated Broca's area. In three of the four MTS tasks, behavioural accuracy was significantly correlated with left lateralisation of DLPFC activity. Brain activation patterns during equivalence thus resembled those involved in semantic processing underlying language, without involving regions concerned with the simple sub-vocal articulation of stimulus names.

Plasma choline in normal newborns, infants, toddlers, and in very-low-birth-weight neonates requiring total parenteral nutrition

Choline deficiency is associated with hepatic abnormalities in adult volunteers and patients administered total parenteral nutrition (TPN). Preliminary investigation has suggested that plasma-free choline concentration (PFCh) is greater in neonatal animals, including humans, than in adults. The aims of this study were to determine the normal PFCh and phospholipid-bound choline concentration (PPLBCh) for newborns, infants, and toddlers and to determine the change during TPN. We also sought to determine the degree of fetal choline extraction, the relation between maternal and newborn plasma choline concentrations, and the relation between plasma choline status and normal newborn length, weight, and gestational age. Blood samples were obtained from 104 full-term newborns in two centers (Ben Taub and Maimonides), 25 mothers, 21 normal infants aged 20.3 +/- 11.8 wk, 12 normal infants aged 62.4 +/- 3.9 wk, and 14 preterm infants (gestational age = 28.9 +/- 2.2 wk) who required TPN. The vein PFChs were 28.1 +/- 13.0 nmol/mL (Ben Taub) and 68.1 +/- 16.9 nmol/mL (Maimonides). The artery PFChs were 27.1 +/- 13.0 nmol/mL (Ben Taub) and 57.9 +/- 11.6 nmol/mL (Maimonides). The vein PPLChs were 1004.7 +/- 246.6 nmol/mL (Ben Taub) and 1121.2 +/- 289.6 nmol/mL (Maimonides). The artery PPLChs were 1065.7 +/- 469.3 nmol/mL (Ben Taub) and 1106.9 +/- 285.8 nmol/mL (Maimonides). The vein-minus-artery differences for PFCh were 1.0 +/- 9.7 nmol/mL (Ben Taub) and 10.2 +/- 10.9 nmol/mL (Maimonides). The vein-minus-artery differences for PPLCh were -51.9 +/- 398.2 nmol/mL (Ben Taub General Hospital, Houston, Texas) and 14.4 +/- 254.3 nmol/mL (Maimonides, New York, New York). Maternal venous PFCh was 8.4 +/- 3.1 nmol/mL. Maternal venous PPLCh was 2592.1 +/- 584.0 nmol/mL (range = 1227.8-3729.0). Maternal venous PFCh correlated with newborn arterial PFCh (r = 0.53, P < 0.05) but not with newborn venous PFCh. No correlation was seen between maternal venous and newborn PPLCh. No significant differences were seen in PPLCh or choline extraction in Ben Taub versus Maimonides patients, although PFCh was significantly greater in the newborns from Maimonides (P < 0.05). The mean venous PFCh and PPLCh in the preterm infants before beginning TPN was 21.2 +/- 6.3 and 1366.8 +/- 339.1 nmol/mL, respectively. Just before initiation of tube feeding (4.0 +/- 2.7 d after TPN had been started), mean venous PFCh and PPLCh was 18.4 +/- 5.3 and 2251.8 +/- 686.9 nmol/mL, respectively. When TPN was discontinued and tube feeding increased to goal, after 10.8 +/- 10.4 d, venous PFCh and PPLCh was 22.6 +/- 8.7 and 2072.5 +/- 540.6 nmol/mL, respectively. Venous PFCh and PPLCh was 13.4 +/- 2.5 and 1827.5 +/- 327.0 nmol/mL, respectively in the older infant group. In conclusion, newborn PFCh is significantly greater than PFCh in adults but falls to adult levels within the first year of life. Low maternal PFCh may be associated with low newborn PFCh. Normal newborn plasma choline status has no bearing on intrauterine growth, although the role of maternal choline deficiency in underweight newborns is unknown. Newborn PPLCh is substantially below that of adults, which suggests its use in membrane synthesis during growth.

Phase I chemotherapy study of biochemical modulation of folinic acid and fluorouracil by gemcitabine in patients with solid tumor malignancies

PURPOSE

This phase I biochemical modulation study evaluated the maximum-tolerated dose (MTD), toxicity, and effectiveness of the combination of folinic acid (FA)/fluorouracil (5-FU) followed by escalated dose levels of gemcitabine (FFG) in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients were refractory to primary treatment and/or without effective treatment options. Twenty-eight patients received an intravenous (IV) infusion of FA 100 mg/m(2) over 1 hour and a 5-FU 450 mg/m(2) IV bolus in the middle of the FA infusion. After the FA infusion, gemcitabine was administered at a steady rate of infusion of 10 mg/m(2)/min over initially 30 minutes and with increases of an additional 15 minutes at each given level. One cycle consisted of six weekly treatments followed by a 2-week rest.

RESULTS

The MTD of gemcitabine was established at 900 mg/m(2) given over 90 minutes. Eight patients of 21 with metastatic colorectal cancer achieved responses (one complete response; seven partial responses), for a response rate of 38%. Responses were seen across the gemcitabine doses of 300 to 900 mg/m(2). One patient had prior treatment with FA/5-FU for advanced disease. Patients with colorectal carcinoma had a median survival of 18 months, and the patient with lung carcinoma has been alive for 24+ months.

CONCLUSION

The combination chemotherapy of FFG was well tolerated and may benefit patients with advanced colorectal carcinoma. A phase II evaluation in this patient population is in progress.

Differential diagnosis of abuse injuries in infants and young children

A complete differential diagnosis is essential when assessing potential child abuse injuries. The differential diagnosis provides clinicians with the opportunity to compare injuries that might mimic abuse with actual abuse-related injuries. The differential diagnosis should delineate the injury type, injury site, instruments used, patterns, and the appearance of old or repeated injuries. This article discusses differential diagnoses that should be considered when evaluating injuries in infants and young children.

Fos immunoreactivity in the lamina terminalis of adrenalectomized rats and effects of angiotension II type 1 receptor blockade or deoxycorticosterone

Neural activity, as measured immunohistochemically by the presence of Fos protein, was determined in the lamina terminalis, a thin strip of tissue forming the anterior wall of the third brain ventricle, after adrenalectomy. Several weeks after surgery, the adrenalectomized rats were maintained with access to water and a low sodium diet for five days. In addition, hypertonic (0.5M) NaCl solution was available for the entire five-day period (sodium available) or only during the first four days (sodium unavailable). The number of neurons expressing Fos, determined at the end of the fifth day, was increased in the adrenalectomized rats with or without NaCl solution to drink. Fos activity in the median preoptic nucleus was increased only in adrenalectomized rats without access to NaCl solution. Treatment of adrenalectomized rats with the sodium-retaining mineralocorticoid hormone, deoxycorticosterone, at the end of the fourth day, decreased Fos expression in the subfornical organ and the organum vasculosum of the lamina terminalis when NaCl solution was available but not when the NaCl solution was unavailable. In the adrenalectomized rats with NaCl solution available, mineralocorticoid treatment decreased both urinary sodium excretion and daily sodium intake. Brain nuclei in the lamina terminalis also became activated in intact rats made sodium deplete by treatment with the diuretic, furosemide. Relative to sodium-deplete intact rats, however, sodium-deplete adrenalectomized rats had a greater number of neurons expressing Fos in the organum vasculosum. Treatment of sodium-deplete rats, adrenalectomized or intact, with the angiotensin II-type 1 receptor antagonist, ZD7155, decreased sodium intake and Fos expression in the subfornical organ but not in the organum vasculosum of the lamina terminalis or median preoptic nucleus. In conclusion, the results demonstrated that activation of the brain nuclei located in the lamina terminalis of adrenalectomized rats was primarily related to sodium deficit and not to the absence of the mineralocorticoid hormones, although the adrenal hormones may have a role in limiting the activation of organum vasculosum of the lamina terminalis during sodium depletion. Furthermore, the results obtained with the administration of the angiotensin receptor antagonist are consistent with the proposal that sodium appetite of the sodium-deplete rat, adrenalectomized or intact, is mediated by circulating angiotensin II acting in the subfornical organ.

The inhibitory effect of hormones associated with stress on Na appetite of sheep

Stress is a large stimulus of Na appetite in rabbits, rats, and mice. This study investigated the influence of some peptides implicated in stress, i.e., adrenocorticotropin (ACTH), corticotropin-releasing factor (CRF), and the recently discovered member of the CRF family, urocortin, on the ingestive behavior of sheep. Intracerebroventricular infusion of these peptides over 4 days decreased the need-free Na intake of Na-repleted sheep. Intracerebroventricular infusion of urocortin, however, did not alter Na intake of Na-depleted sheep. Systemic infusion of ACTH increased, whereas systemic infusion of either urocortin or CRF decreased, Na intake of Na-repleted sheep. The increase in Na intake caused by the peripheral infusion of ACTH was blocked by concurrent i.v. infusion of urocortin, substantiating the inhibitory role of this peptide on Na appetite. Central administration of all peptides and i.v. administration of urocortin or urocortin and ACTH combined decreased food intake. Water intake was not directly influenced by the peptides. Rather, decreased water intake, when observed, was secondary to decreased food intake, as determined by pair-feeding experiments. Whereas systemic infusion of ACTH mimics the increase in Na intake observed in several different stressful situations, CRF and urocortin actually inhibit Na intake, indicating a direct central action overriding any effect of these peptides on ACTH release. Indeed, the inhibition of Na intake by urocortin occurred despite its stimulation of ACTH release and the subsequent increase in peripheral level of cortisol. Thus it would appear that hormones associated with stress have both excitatory and inhibitory influences on Na intake. Presumably, other physiological processes entrained by stress also will be important in determining the quantitative outcome on Na appetite.

Collagenase and gelatinase messenger ribonucleic acid expression and activity during follicular development in the rat ovary

Metalloproteinases are members of a family of proteinases that remodel the extracellular matrix throughout the body. To test the hypothesis that metalloproteinases are regulated by gonadotropin-induced changes during follicular growth, rats were injected with eCG (20 IU, s.c.), and ovaries and serum were collected at the time of eCG administration (0 h) and at 6, 12, 24, 36, or 48 h later for analysis of metalloproteinase mRNA expression, metalloproteinase activity, and steroidogenesis. Serum estradiol levels increased from 18.9 pg/ml at 0 h to 503.8 pg/ml at 48 h. Analysis of mRNA expression was performed for collagenase-3, 72-kDa gelatinase, and 92-kDa gelatinase (n = 3-4). For collagenase-3, eCG stimulated a 32-fold increase in collagenase-3 mRNA at 48 h after eCG injection as compared to that in ovaries collected at the time of eCG administration (i.e., 0-h control). The mRNA levels for 72-kDa gelatinase were 2.8-fold compared to 0 h at 36 h after eCG treatment and returned to control levels by 48 h after gonadotropin treatment. Levels of the 92-kDa mRNA expression peaked at 24 h (4. 2-fold compared to 0 h) and returned to control levels by 36 h. Gel zymography revealed 3 gelatinolytic bands corresponding to the gelatinases of approximately 72 kDa, 92 kDa, and 105 kDa. Analysis of metalloproteinase activity as the degradation of collagen or gelatin per ovary showed an increase in gelatinolytic and collagenolytic activity between 12 and 48 h after eCG treatment. In summary, these findings demonstrate that the gonadotropin induction of folliculogenesis results in changes in the metalloproteinases that may be responsible for extracellular matrix remodeling associated with follicular growth.

Water drinking in rats resulting from intravenous relaxin and its modification by other dipsogenic factors

The purpose of the study was to determine whether iv infusion of relaxin would acutely stimulate water drinking in rats and, if it did, whether such drinking is affected by other dipsogenic stimuli or is blocked by centrally administered losartan. iv infusions of human gene 2 relaxin at doses of 25, 40, 55, or 80 microg/kg x h for 1 h induced dose-dependent water drinking in both male and female rats within 15-30 min of commencement of infusions. iv infusion of a nondipsogenic dose of angiotensin II (0.5 microg/h), combined with relaxin (40 microg/kg x h), almost tripled the relaxin-induced water intake. iv infusion of hypertonic (1 M) NaCl did not potentiate relaxin-induced drinking. Intracerebroventricular injection of the angiotensin AT1 antagonist losartan (10 microg) reduced water drinking induced by iv infusion of relaxin. The water drinking induced by iv infusion of relaxin in the rat suggests that blood-borne relaxin may be a dipsogenic hormone. Potentiation of this relaxin-induced drinking by moderate levels of circulating angiotensin II is additional evidence in support of this view. The results also indicate that a central angiotensinergic neural pathway, utilizing AT1 receptors, subserves relaxin-induced drinking.

Intracerebroventricular infusion of angiotensin II increases water and ethanol intake in rats

The influence of prolonged ingestion of ethanol on stimulation of water or ethanol intake by intracerebroventricular infusion of ANG II was evaluated in rats. Animals were maintained for 5-6 mo with either 10% ethanol solution or water as their only source of fluid. In both groups of rats, infusion of ANG II caused a large increase in water intake (7-fold) and a lesser increase in 10% ethanol intake (2-fold). The effect of ANG II on the volume of ethanol solution ingested, however, was inversely related to the concentration of the ethanol solution. As the concentration of ethanol solution was decreased, frequency and duration of drinking bouts increased. The intake of sweetened 10% ethanol solution or commercially produced wine during infusion of ANG II was similar to the intake of 10% ethanol and not related to taste preference. In conclusion, chronic consumption of ethanol solution did not appear to adversely effect ANG II stimulation of water intake. The intake of ethanol solution during infusion of ANG II was inhibited by a direct effect of ingested ethanol and/or by indirect effect from metabolized ethanol.