Opposite influence of carbohydrates and fat on hypothalamic neurotensin in Long-Evans rats

Neurotensin inhibits food intake when injected in the central nervous system and is released after fat ingestion. The aim of the present study was to measure it in different brain areas and to determine if it is involved in the long-term variations in food intake induced by the ingestion of a high-fat (HF) diet. We compared the results with those obtained with 2 low-fat [high-carbohydrates (HC)] diets and a well-balanced diet. For this purpose, weanling male Long-Evans rats were fed ad libitum for 14 weeks either on a control diet, a HF diet or a HC diet. The rats with the HC (high-starch) diet were divided into 2 subgroups: the first (HC) drank water and the second (HCS) drank a 25% sucrose solution. During the last week of the experiment, energy intake of the HCS rats was significantly greater than that of the 3 other groups of rats (+17.2%; p < 0.01; +27.1%; p < 0.001 and +34.6%; P < 0.001 vs the control, HC and HF rats respectively). NT did not vary in the midbrain and particularly in the ventral tegmental area. Its concentrations were significantly higher in the 2 HC groups than in the HF rats both in the paraventricular (PVN; p < 0.02) and dorsomedial nuclei (DMN; p < 0.03). In the DMN, they were positively correlated with energy intake (r = 0.39; p = 0.027). These results indicate that hypothalamic neurotensin is indeed involved in the long-term modulation of feeding behavior by diet composition and that fat is the more potent macronutrient for its regulation.

The inhibition of alpha-chymotrypsin predicted using theoretically derived molecular properties

The structures and molecular properties of 95 aromatic and heteroaromatic ligands previously tested as reversible inhibitors of chymotrypsin catalysis have been calculated using AMl. The properties obtained have been used as input for multiple linear regression analysis and as descriptors for a back-propagation neural network to predict the binding affinity of alpha-chymotrypsin inhibitors. Using polarizability, molecular shape, electrostatic similarity, dipole moment, ClogP, and the diagonalized quadrupole moments of the ligands, correlation coefficients between calculated and experimental affinities of 0.96 for the training set and 0.89 for the test set were obtained using a neural network. The performance of the multiple linear regression was significantly worse, although useful QSARs were also obtained.

Enhanced feeding response to neuropeptide Y in hypothalamic neuropeptide Y-depleted rats

Monosodium glutamate is neurotoxic for the arcuate nucleus and more generally for all circumventricular organs when injected in newborn rats. Neuropeptide Y, a potent stimulator of food intake, is mainly synthesized in the arcuate nucleus. In the present experiment, we determined the hypothalamic status and the feeding response to intracerebroventricular neuropeptide Y in adult rats neonatally treated with monosodium glutamate. Marked neuropeptide Y decreases were measured in the arcuate nucleus and in the paraventricular nuclei in monosodium glutamate-treated rats (-40%; P < 0.01). Adult rats neonatally treated with monosodium glutamate weighed significantly less (-8%; P < 0.01) and ate less (-10%; P < 0.01) than the control rats. Neuropeptide Y injections in a lateral brain ventricle stimulated food intake in control and monosodium glutamate-treated rats in a dose-dependent manner (P < 0.001). Whatever the time after drug injection (2, 4, 6 and 8 h) and the injected dose (0.5, 1 and 5 micrograms), feeding responses were always greater in monosodium glutamate-treated rats (about 2 times greater starting with the lowest dose (0.5 microgram): 9.3 +/- 1.0 (monosodium glutamate) vs. 5.3 +/- 0.7 (control) g/2 h, P < 0.01). Calculated minimal effective doses were also always smaller in monosodium glutamate-treated rats than in control animals (P < 0.01). Neuropeptide Y increased meal duration, meal size and decreased latency to initiate feeding in monosodium glutamate-treated rats (P < 0.01) and control rats (P < 0.01). For each dose of neuropeptide Y, effects were more pronounced on meal size (+70%) and meal duration (+25%) in monosodium glutamate-treated rats than in control rats. Therefore, monosodium glutamate-treated rats were more sensitive to exogenous neuropeptide Y. Decreased food intake in the monosodium glutamate-treated rats was associated with a decrease in neuropeptide Y concentrations in the arcuate-paraventricular axis. This confirms the functional role of this peptidergic pathway in eating behavior.

Hypothalamic NPY and prepro-NPY mRNA in Djungarian hamsters: effects of food deprivation and photoperiod

Two catabolic states leading to loss of body weight were compared in the Djungarian hamster (Phodopus sungorus campbelli). Hypothalamic neuropeptide Y (NPY) and gene expression for NPY and corticotropin-releasing factor (CRF) were examined after withdrawal of food for 48 h or exposure to short photoperiod for 10 or 20 wk. Food deprivation was accompanied by increases in both NPY and prepro-NPY mRNA in the hypothalamic arcuate nucleus (ARC). Increases in gene expression were limited compared with published data from the rat and were inversely related to predeprivation body weight. Exposure to short photoperiod for 20 wk reduced body weight by 39%, but the activity of the NPY-ergic system was not affected; peptide concentration and gene expression were similar in short photoperiod hamsters and long photoperiod controls. The hypothalamic NPY-ergic system of the Djungarian hamster is sensitive to weight loss due to imposed manipulations of energy balance, but the catabolism observed in short photoperiod gives rise to a body weight that is appropriate to the season encoded by the photoperiod. CRF gene expression was not affected by food deprivation or short photoperiod.

Nitric oxide mediates hyperphagia of obese Zucker rats: relation to specific changes in the microstructure of feeding behavior

The presence of a nitric oxide synthetase (NOS) was demonstrated in the rat brain. It has been demonstrated recently that NOS-inhibitors reduce food intake in mammals and this suggest that nitric oxide (NO) might be a physiological mediator involved in the mechanisms controlling feeding behavior. Actually, there is no information about the acute central and peripheral effects of NOS-inhibitors on feeding behavior in obese and lean Zucker rats. That is why we investigated the acute dose-dependent activity of NG-Nitro-Arginine-Methyl-Ester (L-NAME) on food intake and feeding behavior in these rats. When given peripherally in the obese rats, L-NAME produced a dose-dependent decrease in food intake (p<0.001). The calculated MED and the ED 50 were 0.50 mg/kg IP and 3.46 mg/kg IP, respectively. These effects could not be reproduced in the lean Zucker rats whatever the dose used (p=0.59). The anorectic properties of L-NAME were very well translated into the microstructure of the feeding behavior. Time spent to eat (p<0.001), meal duration (p<0.01) and meal number (p<0.01) were reduced in the obese rats. Interestingly, L-NAME produced the same effects in the lean rats, but meal size increased in a compensatory manner. Central administration of L-NAME reproduced the same effects in the obese rats, but lean rats still remained insensitive. Central aminergic and/or peptidergic defects associated with the expression of hyperphagia might explain the differences observed between these lean and the obese animals. These results indicate a role of nitric oxide in the expression of hyperphagia and show that it might be a physiological mediator involved in the mechanisms controlling feeding behavior.

Comparison of Mycoplasma arthritidis strains by enzyme-linked immunosorbent assay, immunoblotting, and DNA restriction analysis

Twenty Mycoplasma arthritidis strains or isolates were compared by a combination of enzyme-linked immunosorbent assay by an antiserum adsorption technique, Western immunoblotting, and restriction analysis of chromosomal DNA. Antigenic markers that defined strains related to strains 158p10p9, PG6, and H606 were identified. In addition, restriction analysis allowed all 20 strains to be divided into six groups. Results of restriction analysis corresponded generally with antigenic similarities, although the former did not allow grouping with as fine a precision as the latter. However, intrastrain antigenic variability, which is common among many Mycoplasma species, including M. arthritidis, introduced a complicating factor into our attempts at antigenic analysis. While serologic and antigenic analyses remain useful, we recommend that they be used with caution and in combination with other techniques for identifying and characterizing new isolates and newly acquired strains. Combinations of these techniques have proven to be useful in our laboratory for quality control and for uncovering interesting relationships among strains subjected to animal passage and their less virulent antecedents and among strains originally classified as the same but obtained from different sources and maintained, sometimes for decades, in different laboratories.

[Follow-up of psychiatric disorders and specific developmental delay disorders in special education students]

In a prospective longitudinal study 72 children who were attending a special school for children with learning disabilities in Erlangen were examined in 1990 and again in 1992/93. At the first examination the children's mean age was 7 years 1 month and at the second 8 years 10 months. The sample contained many more boys than girls. Reported here are the findings on the course of the psychiatric disorders and the specific developmental disorders of speech and language and motor function. There was a marked decrease in the prevalence of psychiatric disorders. Of the 17 children with a psychiatric disorder at follow-up, 13 (76%) also had a disorder at the start of the study and of the 23 with a psychiatric disorder at the start 13 (57%) still had a disorder at follow-up. Children with enuresis and those with disturbances of activity or attention had the best prognosis. The special school had a positive effect on conduct. The prevalence of specific developmental disorders also decreased over the two-year period. As expected, specific speech articulation disorders had the best prognosis. All other disorders had a poor prognosis. Increases in prevalence were mainly the result of different cutoff points for a given diagnosis at different ages. The high number of specific disorders of motor function at both time points is especially noteworthy.

Neurotensin decreases with fasting in the ventromedian nucleus of obese Zucker rats

Neurotensin (NT) inhibits food intake when injected either in brain ventricles or in hypothalamic nuclei such as the ventromedian nucleus (VMN). NT concentrations are lower in obese than in lean Zucker rats in several hypothalamic nuclei, including the VMN. In this experiment, we studied the influence of the feeding state on NT concentrations in different brain areas of 10-week-old lean (n = 27) and obese (n = 27) Zucker rats that were fasted for 48 hours and then refed for 6 hours. NT level was measured in the microdissected areas by radioimmunoassay. Obese rats ingested approximately 50% more food than lean rats in the ad libitum (ad lib) condition (P < .001) and 12% more during the refeeding time (NS). NT concentrations in the median eminence (ME) were 50% lower in obese than in lean rats (P < .001). This decrease could be related to a 20% decrease in the arcuate nucleus (ARC) of the obese rats (P < .04). NT concentrations in the ME and ARC, which are important for the control of pituitary hormone secretion by NT, were not changed by the feeding state in both genotypes. NT varied with the feeding state in the VMN only (P < .04). Concentrations were 45% lower in fasted (FD) obese rats than in ad lib or refed (RF) obese rats (1.09 +/- 0.25 ng/mg protein v 1.98 +/- 0.36 ad lib and 1.62 +/- 0.11 RF, P < .05). They remained unchanged in lean rats. NT variations in the VMN of obese rats could contribute synergistically with other neuropeptides to the abnormal feeding behavior of these rats.

[Intelligence and language performance of special education children at 7 and 9 years of age]

Prospective longitudinal data from children at a school for learning disabled were obtained. Intelligence and language scores were assessed at first grade and two years later. The results of two samples from Erlangen and München showed a high stability of the intelligence scores but less stability of the language scores. There were remarkable improvements in language comprehension. Expressive language had a constant lag compared with the test-standard of children of the same age; the articulation did improve as expected. The children from this special school still had problems with verbal short term memory.

Origin of serum alpha-amylase isoenzymes from healthy adult rats

In connection with common use of rats in experimental testing drug toxicity in the liver or pancreas, we checked the electrophoretic patterns of amylase isoenzymes extracted from the liver, pancreas, parotis and serum of healthy adult rats. Separation of isoenzymes was made by polyacrylamide gel electrophoresis. The results indicate the salivary glands and liver as sources of serum alpha-amylase.

Mosaicism confined to placenta in pregnancies with adverse outcome

Chorionic villi and fetal tissues from 50 pathological human conceptions at gestational weeks 9-40 were cultured and cytogenetically analyzed to explore the existence of chromosomal mosaicism confined to the extraembryonic tissues and to clarify the relationship between confined placental mosaicism and adverse outcome of pregnancy. Chorionic villi and fetal tissues from 12 second trimester gestations terminated for social reasons served as a control group. In two pathological gestations, true mosaicism was found exclusively in chorionic cells and could not be confirmed in cells derived from the fetal tissues. One of these was severely growth retarded. Concordant results were obtained in all other cases.

[Mosaicism confined to placenta in pregnancies with adverse outcome]

Chorionic villi and fetal tissues from 50 pathological human conceptions at gestational weeks 9-40 were cultured and cytogenetically analyzed to explore the existence of chromosomal mosaicism confined to the extraembryonic tissues and to clarify the relationship between confined placental mosaicism and adverse outcome of pregnancy. Chorionic villi and fetal tissues from 12 second trimester gestations terminated served as a control group. In two pathological gestations true mosaicism was found exclusively in chorionic cells and could not be confirmed in cells derived from the fetal tissues. One of these was severely growth retarded. Concordant results were obtained in all other cases.

Involuntarily detained HIV-infected patients in Sweden: reasons for referral and psychiatric diagnoses

The Swedish Communicable Diseases Act permits the isolation of an HIV-infected person if there is risk of disease transmission. The purpose is for the patient to receive the support needed to alter his or her attitude and behaviour so that the isolation can be terminated. This study describes the reasons for referral and the psychiatric diagnoses of 34 isolated HIV-infected patients. All patients who were isolated in Stockholm from 1986 to 1993 were included. Psychiatric data were collected from their psychiatric records. The most frequent reason for referral was unprotected sex with a partner who was not informed about the infection. The most common psychiatric diagnosis was amphetamine or opiate abuse. Drug users without delusions and immigrants with adjustment disorders or post-traumatic stress disorder had the shortest treatment periods. All patients belonged to underprivileged groups, were drug users or refugees. More effort is needed to teach these groups about HIV.

Putative neuropeptide Y antagonist failed to decrease overeating in obese Zucker rats

A central dysregulation of several neuropeptides could be at the origin of the marked hyperphagia of the obese Zucker rat, a well-known animal model used for the study of obesity. Neuropeptide Y (NPY), which stimulates food intake and increases early in life in obese rats, plays a major role in the development of this hyperphagia. The aim of our experiment was to test a proposed NPY antagonist namely PYX-2 in obese hyperphagic Zucker rats in order to know if it could be an interesting drug for limiting their food intakes. Four doses of PYX-2 (50-1000 pmol) were injected in a counterbalanced order in the lateral brain ventricles of 10 adult male Zucker rats. Food intake was recorded 0.5, 1, 2, 3, 6, and 23 h after PYX-2 injection and compared either to the rat's spontaneous food intake or to the food intake following injection of artificial CSF (vehicle) only. It was not modified by any dose of PYX-2 whatever the time considered (1 h after injection: 4.3 +/- 0.5 (1000 pmol) vs 4.6 +/- 0.8 (CSF) g; 23 h period: 27.0 +/- 1.9 (1000 pmol) vs 26.6 +/- 2.9 (CSF) g; N.S.). Thus, PYX-2, the putative NPY antagonist, totally failed to inhibit food intake in the obese rats. The absence of effect of PYX-2 on food intake can be explained by the structure of PYX-2, a modified 27-36 amino acid sequence that may not be recognized by the Y1-type NPY receptors which are involved in the regulation of feeding behavior.

Increased threshold concentrations of neuropeptide Y for a stimulatory effect on food intake in obese Zucker rats--changes in the microstructure of the feeding behavior

A central dysregulation of several neuropeptides could be at the origin of the marked hyperphagia of the obese Zucker rat, a well-known animal model used for the study of obesity. Neuropeptide Y (NPY), which strongly stimulates food intake and increases early in life in obese rats, plays a major role in the development of this hyperphagia. The aim of our experiment was to measure the feeding responses of lean (n = 8) and obese (n = 17) male Zucker rats to several doses of exogenous NPY injected in the lateral brain ventricle. We analyzed the microstructure of the rats' feeding behavior with an automatic device for 8 h post-injection. NPY stimulated food intake both in the lean and obese rats in a dose-dependent manner (P < 0.001). However, the minimal effective dose was always 3-4 times greater in the obese rats than in the lean ones (range: 0.43-0.53 vs. 0.12-0.18 microgram/brain; P < 0.001). Meal size, meal duration and time spent eating significantly increased in the lean rats (P < 0.05 or less). The last two parameters also increased in the obese rats but with the highest dose (5 micrograms) only. The obese Zucker rats were therefore less sensitive to NPY than the lean ones, probably because of their already high endogenous NPY levels. The modifications in the eating behavior indicate that NPY could overcome the satiety signals.

Paget's disease in a squamous metaplasia of the urinary bladder. The first published case of a disease which is usually found in the epidermis

Extramammary Paget's disease is usually found in epidermis and is often associated with malignancy in visceral organs. We report the first case with Paget's disease developed in metaplastic squamous epithelium in the urinary bladder.

Reversals of blood-brain barrier disruption by catalase: a serial magnetic resonance imaging study of experimental optic neuritis

PURPOSE

To investigate serially the role of catalase detoxification of endogenous H2O2 in the disruption of the blood-brain barrier (BBB) and demyelination of experimental optic neuritis.

METHODS

Serial contrast-enhanced magnetic resonance imaging (MRI) of the optic nerves (T1 weighted) and T2 weighted MRI without contrast were performed on 18 guinea pigs 3 to 14 days after sensitization with central myelin for experimental allergic encephalomyelitis. Sex and age-matched littermates were paired and sensitized with the identical antigenic emulsion. To detoxify endogenous hydrogen peroxide (H2O2), animals received daily intraperitoneal injections of polyethylene glycol (PEG)-catalase at a dose of 12,000 U/kg per day for 3 days, then 1,200 U/kg daily for the next week, commencing 3 days after antigenic sensitization. Littermates received an equal volume of preservative-free saline. The intensity of gadolinium-DTPA (Gd-DTPA) enhancement was quantitated by obtaining the value for a region of interest (ROI) of the right optic nerve and the left optic nerve. The effect of H2O2 detoxification by catalase was evaluated by differences in the intensity of Gd-DTPA enhancement and T2 weighted signal in the ROI of the right and the left optic nerves at 7, 10, and 14 days after antigenic sensitization, from the pretreatment value obtained at day 3. The effectiveness of catalase detoxification of H2O2 was assessed with quantitative ultracytochemical localization of electron-dense, H2O2-derived cerium perhydroxide in the optic nerves.

RESULTS

With PEG-catalase treatment, mean differences for Gd-DTPA enhancement in the ROI at 7, 10, and 14 days after antigenic sensitization were significantly reduced from the pretreatment values obtained 3 days after antigenic sensitization compared with the comparable interval values for untreated littermates. For T2 weighted signal intensity, only the 7- and 14-day values were significantly less with PEG-catalase compared with values for littermates obtained at comparable intervals. Quantitative ultracytochemical localization of H2O2-derived cerium perhydroxide reaction product revealed significant reductions in the medium number of cerium particle counts of the optic nerve head, sheath, and myelinated retrobulbar nerve.

CONCLUSIONS

PEG-catalase reduced H2O2-derived cerium perhydroxide reaction product in the optic nerve but did not eliminate it, reversed disruption of the BBB as measured by Gd-DTPA enhancement, and reduced demyelination and edema as measured by T2 weighted signal intensity, suggesting detoxification of H2O2 as a new treatment strategy for disorders of primary demyelination of the central nervous system.

True trisomy 15 mosaicism, detected by amniocentesis at 12 weeks of gestation and fetal echocardiography

A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications.

Disruption of the blood-brain barrier in experimental optic neuritis: immunocytochemical co-localization of H2O2 and extravasated serum albumin

PURPOSE

To probe the role of endogenous hydrogen peroxide (H2O2) in the pathogenesis of disruption of the blood-brain barrier (BBB) associated with experimental allergic encephalomyelitis (EAE), an animal model for primary central nervous system demyelination.

METHODS

Strain-13 guinea pigs were sensitized for EAE with central myelin in complete Freund's adjuvant. Magnetic resonance imaging with Gd-DTPA was performed twice a week for 2 weeks to assess disruption of the BBB, in vivo, by the enhancement of the optic nerves. Two weeks after antigenic sensitization, ultracytochemical localization of endogenous H2O2 was performed using the cerium perhydroxide method, with co-localization of endogenous serum albumin extravasation using gold-labeled antibodies against serum albumin. Examination of blood vessels for perivascular immunogold-labeled serum albumin and H2O2 derived reaction product began in the optic nerve head and proceeded toward the retrobulbar optic nerve until a total of 20 vessels were evaluated per animal.

RESULTS

Magnetic resonance imaging revealed Gd-DTPA enhancement of the optic nerves in all animals sensitized for EAE. Optic nerve ultrastructure revealed colloidal gold-labeled antibodies against serum albumin in the perivascular and adjacent interstitial spaces of capillaries and small venules in which H2O2 derived cerium perhydroxide reaction product was also simultaneously evident. Immunogold-labeled serum albumin was predominantly confined to the intravascular compartment of the optic nerve in the absence of perivascular H2O2 and/or perivascular foci of inflammatory cells. The difference between the mean percentage of blood vessels (61.8%) with co-localization of perivascular immunogold-labeled serum albumin and cerium perhydroxide reaction product, to the mean percentage of blood vessels (9.5%) with perivascular immunogold-labeled serum albumin in the absence of cerium perhydroxide, was statistically significant (P = 0.0019).

CONCLUSIONS

Endogenous H2O2, found at the foci of BBB disruption, may be one of the mediators involved in the alteration of vascular permeability in experimental optic neuritis.

Macronutrient type independently of energy intake modulates hypothalamic neuropeptide Y in Long-Evans rats

Neuropeptide Y (NPY) induces a robust feeding response when it is injected in the hypothalamus. It stimulates both carbohydrate and fat intakes. Diets rich in either macronutrient are known to induce obesity and to modify feeding behavior. The aim of the present study was to determine the effects of long-term ingestion of these diets on hypothalamic NPY in relation with food intake and body weight gain and composition. For this purpose, three groups of weanling Long-Evans rats were fed either a well-balanced diet, a high-carbohydrate (HC) diet (high starch plus 25% sucrose solution), or a high-fat (HF) diet during 14 weeks. Body weight and food intake were recorded during this period. At the end of the experiment, NPY was measured in several microdissected brain areas, and some adipose tissues (AT) depots were sampled. HF rats weighed significantly more than the two other groups (p < 0.02). They were also fattier (+ 30-50% in AT weights; p < 0.01). Energy intake (EI) of the HC rats was significantly greater than that of the control (+ 15%; p < 0.02) and HF rats (+ 34%; p < 0.01) during the week preceding killing. EI of HF rats over the whole experiment was lower than that of the two groups (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Neuropeptide Y projection from arcuate nucleus to parvocellular division of paraventricular nucleus: specific relation to the ingestion of carbohydrate

Neuropeptide Y (NPY) injection into the hypothalamic paraventricular nucleus (PVN) stimulates feeding behavior and specifically carbohydrate intake in rats. The present study investigated the relation between endogenous levels of NPY and natural ingestion for carbohydrate. It also examined the possible importance of a specific NPY projection in this relationship, which traverses from cell bodies in the arcuate nucleus (ARC) to terminals in the parvocellular division of the PVN (pPVN). Sprague-Dawley rats were given pure macronutrient diets (carbohydrate, protein and fat), and their daily nutrient intake was recorded for 3 weeks. The rats were sacrificed, and 8 hypothalamic nuclei were micropunched and examined via RIA for endogenous NPY levels. The results demonstrate a strong, positive correlation between daily carbohydrate intake and hypothalamic NPY levels. The relationship was specific to the pPVN (r = +0.71; P < 0.001), ARC (r = +0.57; P < 0.001) and dorsomedial nucleus (DMN, r = +0.52; P < 0.01), and was not observed in any other hypothalamic area, including the magnocellular division of the PVN. In the pPVN, the NPY levels of animals that consumed > 50 kcal of carbohydrate (49 pg/microgram protein) were almost twice that of animals that consumed < 20 kcal of carbohydrate (28 pg/microgram protein: P < 0.01). Furthermore, NPY levels in the ARC were positively correlated with NPY in the pPVN and DMN but not any other nuclei. No relation between hypothalamic NPY and measures of protein or fat ingestion was detected. Levels of NPY were also unrelated to total caloric intake, to body weight at sacrifice, and to body weight gain during the 3-week measurement period. These results, together with other findings, provide support for a role of endogenous NPY and its projection from the ARC to the pPVN, perhaps via the DMN, in controlling natural appetite for carbohydrate.

Microdialysis in the estimation of interstitial myocardial neuropeptide Y release

The purpose of this study was to investigate the feasibility of cardiac microdialysis for the in vivo estimation of cardiac interstitial peptide concentrations, and, to determine the changes in neuropeptide Y release in myocardial tissue during experimental brain death in pigs. Using a specifically designed concentric flexible probe, perfused with Ringer solution containing 0.5% of bovine serum albumin at a flow rate of 2 microliters/min, allowed us to obtain a 23 +/- 2% relative recovery rate in vitro. Based on these in vitro recovery data, a regional study of the kinetics of interstitial NPY levels following brain death was obtained by monitoring the changes in NPY dialysate levels recorded from dialysis probes implanted into the right and left ventricular walls of the beating heart in vivo. Basal dialysate NPY levels determined by radioimmunoassay were of 95.2 +/- 7.0 and 93.2 +/- 9.1 pmol/l in left and right ventricle, respectively. Brain death was followed by a sustained 2 h increase in NPY dialysate levels in both ventricles (peak levels: 173.2 +/- 30.9 pmol/l in left ventricle, and 149.7 +/- 23.9 pmol/l in right ventricle), which then returned to control levels. We conclude that cardiac microdialysis is a simple and promising new tool for evaluating the role of peptides in cardiovascular regulation.