A tribute to Dr Francis Roe: 50 years of outstanding achievement.
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Carcinogenicity Tests↗
Biomedical subjects
P Grasso
Publications and source records attributed to P Grasso.
Clinical evaluation of oxidative stress and myocardial reperfusion injury in pediatric cardiac surgery.
BACKGROUND: To evaluate oxidative stress and myocardial damage after aortic crossclamping release (ACCR) during cardio pulmonary bypass (CPB) in children two parameters were investigated: total glutathione (GSH) and its oxidoreductive reactions (GSH/GSSG) as expression of oxidative stress, and plasmatic turnover of myocardial taurine (TAU) as expression of cell damage. METHODS: The study was divided in two periods: 1) first period: analysis of oxidative stress and myocardial damage in 18 children. 2) Second period: evaluation of myocardial cell protection by controlled anterograde low oxygen warm reperfusion (ALOWR) before declamping. Twenty-one children were divided in two groups: not receiving (Group 1, 9 patients) and receiving (Group 2, 12 patients) ALOWR. RESULTS: In the first period GSH values increased significantly after onset of mechanical ventilation (MV) in vein, after CPB start in artery and after ACCR in coronary sinus. Moreover TAU turnover in aortic and coronary sinus blood increased significantly after ACCR. In the second period, Group 2 showed a lower oxidative stress after ACCR, while no differences were observed in TAU turnover. CONCLUSIONS: 1) Assessment of TAU and GSH levels can be considered a good method to clinically evaluate myocardial injury during cardiac surgery. 2) MV and CPB can induce oxidative stress before aortic clamping and can decrease the physiologic scavengers. Therefore, to prevent that depletion, the strategy of these techniques must be adapted to the patient and to his cardiac disease. 3) Intramyocardial TAU turnover is not significantly modified by the reperfusion technique. 4) ALOWR can reduce myocardial oxidative stress and can improve heart recovery after the cardioplegic arrest.
Cardiopulmonary Bypass↗
[D-LEU-4]-OB3, a synthetic leptin agonist, improves hyperglycemic control in C57BL/6J ob/ob mice.
We have recently shown that the activity of a synthetic peptide corresponding to amino acid residues 116-130 of secreted mouse leptin is contained in a restricted sequence at the amino terminus of the peptide, between residues 116-122 (Ser-Cys-Ser-Leu-Pro-Gln-Thr, OB3). Substitution of the Leu residue at position 4 of OB3 with its D-isomer ([D-Leu-4]-OB3) enhanced the ability of OB3 (1 mg/day, ip, 7 days) to reduce body weight gain, food and water intake, and serum glucose in female C57BL/6J ob/ob mice. In the present study, we have utilized a pair-feeding approach to demonstrate that the antihyperglycemic action of [D-Leu-4]-OB3 is not solely due to its effects on caloric intake. One group of female C57BL/6J ob/ob mice (n=6) was fed ad libitum, and two additional groups (n=6 per group) were allowed 3.0 g food/mouse daily, an amount previously determined to satisfy [D-Leu-4]-OB3-treated mice. At the end of the 7-day test period, vehicle-injected mice fed ad libitum were approximately 10% heavier than their initial body weights, while pair-fed mice injected with vehicle and [D-Leu-4]-OB3-treated mice lost 5% of their initial body weights. After 1 day of treatment, blood glucose was reduced by 20% in pair-fed vehicle-injected mice, and by 40% in mice given [D-Leu-4]-OB3. Food restriction reduced blood glucose throughout the 7-day study, but not to levels seen in wild-type nonobese C57BL/6J mice of the same sex and age. After 2 days of treatment with [D-Leu-4]-OB3, however, blood glucose was reduced to levels comparable to those seen in wild-type nonobese mice. [D-Leu-4]-OB3 also lowered serum insulin levels by 53% when compared to mice fed ad libitum. Neither pair-feeding nor [D-Leu-4]-OB3 treatment had any apparent effect on thermogenesis. These results suggest that [D-Leu-4]-OB3 exerts its effects on serum glucose not only by suppressing caloric intake, but also through a separate effect on glucose metabolism which may involve increased tissue sensitivity to insulin.
Animals↗
Design of a synthetic leptin agonist: effects on energy balance, glucose homeostasis, and thermoregulation.
We have previously reported that a synthetic peptide amide corresponding to amino acid residues 116-130 of mouse leptin, LEP-(116-130), reduces body weight gain, food intake, and blood glucose levels in ob/ob and db/db mice. In the present study we show that the activity of LEP-(116-130) resides in a restricted sequence between amino acid residues 116-122. A synthetic peptide corresponding to this sequence (Ser-Cys-Ser-Leu-Pro-Gln-Thr) has been named OB3. Single point D-amino acid substitution was used to study the structure-function relationship of each residue in OB3. D-Amino acid analogs of OB3 were synthesized by the solid phase method, purified to 98+%, and administered (1 mg/day, ip) for 7 days to female C57BL/6J ob/ob mice. The effects of the peptides on body weight gain, food and water intake, glucose homeostasis, and thermoregulation were assessed. In most cases, the efficacy of OB3 on all parameters tested was reduced by substitution of an L-amino acid with its corresponding D-isoform. A statistically significant increase (2.6-fold) in the weight-reducing effect of OB3, however, was observed by inversion of the configuration of the leucine residue at position 4 (Leu-4) of OB3 by substitution with its D-amino acid isoform [D-Leu-4]. Compared with OB3, mice treated with [D-Leu-4]-OB3 consumed 7.9% less food and 16.5% less water. Blood glucose was normalized to levels comparable to those in wild-type control mice within 2 days after initiation of [D-Leu-4]-OB3 treatment. Unlike native leptin, however, neither OB3 nor any of its D-amino acid-substituted analogs had any apparent effect on thermogenesis. Our results indicate that synthetic peptide strategies may be useful in the development of potent and stabile pharmacophores with potential therapeutic significance in the treatment of human obesity and its related metabolic dysfunctions.
Amino Acid Substitution↗
Epitope mapping of secreted mouse leptin utilizing peripherally administered synthetic peptides.
We have recently reported that intraperitoneal (i.p.) administration of synthetic peptide amides corresponding to amino acids 106-140 of mouse leptin significantly reduced food intake and body weight gain in female C57BL/6J ob/ob mice. These results suggested that leptin activity was localized in domains toward its C-terminus between residues 106-140. In the present study, 14 overlapping peptides encompassing the complete sequence of secreted mouse leptin were synthesized, and their effects on body weight and food intake in female C57BL/6 J ob/ob mice were assessed. When given as seven daily 1-mg i.p. injections, only peptides corresponding to amino acids 106-120, 116-130 and 126-140 caused significant reductions in body weight and food intake. These results confirmed our earlier study and suggest that in contrast to the domain encompassed by amino acids 106-140, the N-terminal of mouse leptin between amino acids 21-105 may not contain functional epitopes that can be utilized as lead compounds in the development of peripherally administered bioactive peptide analogs or nonpeptide mimetics of leptin, which may have potential usefulness in treatment of the energy imbalance associated with obesity.
Amino Acid Sequence↗
A synthetic peptide corresponding to amino acid residues 90 to 95 of human follicle-stimulating hormone beta-subunit delays the onset of puberty in female Swiss Webster mice.
We have recently reported that a synthetic peptide corresponding to amino acid residues 81-95, a receptor-binding region of the human FSH-beta-subunit, and a subdomain within this region, hFSH-beta-(90-95) (DSTDCT), prolonged vaginal estrus when administered intraperitoneally (ip) to normally cycling Swiss Webster mice. These results were similar to those we reported for a synthetic peptide corresponding to hFSH-beta-(34-37) [TRDL, a subdomain within receptor-binding region hFSH-beta-(33-53)] in the same model system. TRDL also accelerated the onset of puberty in immature mice. We now report the effects of hFSH-beta-(90-95) in prepubertal female mice. In two separate experiments, a single ip injection of 200 microg/g body weight (BW) hFSH-beta-(90-95) in phosphate buffered saline (PBS, vehicle) administered to mice on day 28 delayed first vaginal estrus by 3 days in 50% (4/8) and 62.5% (6/8) when compared to mice given vehicle alone on day 28. Vaginal opening was also delayed in mice receiving hFSH-beta-(90-95) when compared to mice injected with vehicle alone. Serum estradiol levels of vehicle-injected control mice in first vaginal estrus were three-fold higher than in mice treated with hFSH-beta-(90-95), whose vaginal smears showed no evidence of first estrus. No significant differences in ovarian or uterine weights, or serum progesterone levels, were observed between vehicle-injected control mice achieving first vaginal estrus and mice receiving hFSH-beta-(90-95) in whom first estrus was delayed. The contrasting effects on the onset of puberty of hFSH-beta-(90-95) (delay) and hFSH-beta-(34-37) (acceleration) may reflect synthetic peptide binding to different domains of the FSH receptor, resulting in variable post-binding effects. These results are consistent with our earlier study suggesting that FSH-beta-subunit-related synthetic peptides can induce significant in vivo effects on the onset of puberty in female mice.
Animals↗
Cysteine residues in a synthetic peptide corresponding to human follicle-stimulating hormone beta-subunit receptor-binding domain 81-95 [hFSH-beta-(81-95)] modulate the in vivo effects of hFSH-beta-(81-95) on the mouse estrous cycle.
We have previously reported that synthetic peptide amides corresponding to subdomains of the human FSH 3-subunit, hFSH-beta-(33--53) and hFSH-beta-(81--95), interact with the external domain of the FSH receptor in two in vitro model systems. Consistent with these in vitro observations, we found that intraperitoneal (i.p.) administration of each of these peptides prolonged vaginal estrus in normally cycling mice in vivo. Both hFSH-beta-(33--53) and hFSH-beta-(81--95) contain cysteine (Cys) residues with free sulfhydryl groups of potential significance in receptor interactions. To assess the possible involvement of these groups in the in vivo effects of hFSH-beta-(33--53) and hFSH-beta-(81--95), synthetic peptide analogs were prepared in which all Cys residues were replaced with serine (Ser). In the present study, we demonstrate that the in vivo effect of hFSH-beta-(33--53) on the mouse estrous cycle, extension of vaginal estrus, was not changed by substitution of Cys-51 with Ser. In contrast, mice receiving the Ser-substituted analog of hFSH-beta-(81--95) had normal estrus stages, but were arrested in diestrus. hFSH-beta-(33--53)-(81--95), a linear peptide encompassing both domains, also prolonged vaginal estrus. The Ser-substituted analog of this peptide, however, prolonged vaginal estrus in some of the mice tested and induced cycle arrest at diestrus in others. hFSH-beta-(90--95), the active subdomain at the C-terminus of hFSH-beta-(81--95), extended vaginal estrus, but diestrus stages were of normal duration. Its Ser-substituted analog, however, prolonged the estrus stage of the majority of mice treated, but induced diestrus arrest in some. The differing responses to these peptides are presumably due to interactions of the synthetic peptides with different regions of the FSH receptor. This further suggests that one consequence of ligand interaction with multiple receptor binding domains may be variable effects on ovarian function, and that Cys to Ser analogs may have value in the design of a novel class of synthetic peptides capable of fertility regulation and control.
Amino Acid Sequence↗
Level, sources and toxicity of polychlorinated biphenyls in the Italian diet.
We used the duplicate portion method to measure the daily dietary intake of total and congener-specific polychlorinated biphenyls (PCB) and to assess their potential toxicity in a group of 20 subjects consuming a typical Italian diet. The mean +/- SD intake of total PCB, measured by GC-MS, was 3.72 +/- 1.51 micrograms/person/day, comparable to values reported in similar studies world-wide, with individual intakes varying within one order of magnitude, from 0.97 to 10.59 micrograms/person/day. The di-ortho congeners 153, 18 and 138 were the PCB found in the highest concentrations (respectively 13.8%, 11.4% and 10.9% of the total) while the non-ortho coplanar congeners (77, 126 and 169) amounted to 0.5% of the total. The corresponding levels of toxicity (TCDD-like TEQ values ascribable to PCB) ranged from 4.6 up to 119 pg/person/day of TCDD-equivalents in 18 subjects, i.e. presumed no-risk levels, but with peaks of 2109 and 4553 pg/person/day in two subjects with significant intakes of the congener 126. Principal components analysis and redundancy analysis showed dairy products, meat and fish were the principal sources of PCB, and vegetables those with the highest toxicity index in the Italian diet.
Adult↗
Inhibitory effects of leptin-related synthetic peptide 116-130 on food intake and body weight gain in female C57BL/6J ob/ob mice may not be mediated by peptide activation of the long isoform of the leptin receptor.
We recently reported that intraperitoneal administration of leptin-related synthetic peptide 116-130 [LEP-(116-130)] resulted in reduced food intake and significant weight loss in homozygous female C57BL/6J ob/ob mice. In this study, we used two in vitro bioassays to show that the interaction of LEP-(116-130) with the long form of the leptin receptor (OB-Rb), the receptor isoform that is predominantly expressed in the hypothalamus, is not required for the observed in vivo effects of the peptide on energy balance. LEP-(116-130) was unable to compete the binding of alkaline phosphatase-leptin fusion protein to OB-R. Moreover, LEP-(116-130) was unable to activate signal transduction by OB-Rb in vitro. In homozygous female C57BLKS/J-m db/db mice that do not express OB-Rb, intraperitoneal administration of LEP-(116-130) reduced body weight gain and blood glucose levels but not food intake, which further supports a mechanism of action that does not require peptide interaction with OB-Rb.
Animals↗
Deuterated internal standards for gas chromatographic-mass spectrometric analysis of polar organophosphorus pesticides in water samples.
It is essential to know whether drinking water contains any pesticides up to concentrations close to the European Union limit of 0.1 microgram/l, in order to protect the population. Mass spectrometry (MS) using a suitable internal standard (I.S.) should improve the quantitative analysis of pesticides, the I.S. circumventing loss of compounds during the analytical procedure and correcting the analytical variability. In this study we verified this assumption in GC-MS, synthesising specific internal standards for four organophosphorus pesticides with poor stability, comparing the performances with and without the I.S.
Deuterium↗
Reducing the vertical transmission of HIV. Italian obstetricians often don't ask women to take test.
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Attitude of Health Personnel↗
Smokeless tobacco and oral cancer: an assessment of evidence derived from laboratory animals.
No carcinogenic activity was observed when snuff was inserted into the cheek pouch of the hamster or spread over the oral mucosa. This negative result was obtained in a number of experiments whether snuff was applied once only and left in place for several months or inserted repeatedly for up to 2 years. In the rat, a few tumours were observed when snuff was inserted into the artificial lip canal. The insertion appeared to cause a considerable reaction in the surrounding tissue so it is plausible to assume that trauma plays an important role in the development of these tumours. An extract of snuff applied to the oral mucosa of the rat did not produce any tumours, but an extract enriched by the addition of 10 times the naturally-occurring amounts of NNN and NNK produced a few benign tumours at the site of application. A higher incidence of tumours was produced when an equivalent amount of an aqueous solution of these two nitrosamines was applied directly to the oral mucosa, suggesting, according to the authors, that snuff inhibits the carcinogenic activity of TSNAs. Initiation/promotion studies were carried out on snuff in the rat in order to explore further its carcinogenic potential. The results were consistent with the conclusion that snuff does not possess any promotional activity. No increase in tumour incidence was observed in mice when snuff was given in the diet at concentrations of 25% gradually decreasing to 5% in a 14 month study. A negative result was also obtained in the rat given snuff at a concentration of 5% for 18 months. In hamsters given snuff at a concentration of 20% for 2 years, forestomach tumours occurred. A comparable incidence of this type of tumour occurred in animals given 20% cellulose. The result of this study does not provide valid evidence of carcinogenicity. HSV and snuff applied orally in the hamster produced a high incidence of squamous cell carcinomas. The sustained high level of squamous cell hyperplasia generated by the experimental design could account for the development of these tumours. Despite the defects in some of the earlier studies, the sum total of this experimental work suggests that snuff is not carcinogenic to the oral mucosa of the hamster or the rat. It is also unlikely to cause tumours in other tissues in these species. These results give some degree of reassurance that snuff is not likely to be carcinogenic to the human oral mucosa. The interaction of snuff and HSV viruses is, at the moment, questionable and requires further investigation.
Animals↗
Application of guidelines for occupational HIV infection control during delivery in Italy.
OBJECTIVE: We surveyed the attitudes of Italian obstetricians toward the application of HIV infection control guidelines during labour and delivery proposed by the Italian National Committee for HIV Infection. STUDY DESIGN: We identified 66 obstetric centres affiliated to the AOGOI (Association of Italian Gynecologists and Obstetricians). A postal questionnaire was sent to 752 physicians in charge in the centres. RESULTS: A total of 419 clinicians (55.7%) completed and returned the form to the coordinating centre. Obstetricians were directly asked about the need for routine adoption of the Italian guidelines for delivery of women with positive or unknown HIV status (indicating the routine use during delivery of protective glasses, impermeable garments, mask and sterile latex gloves, the washing of hands with detergent solution after using gloves and collection of needles and sharp instruments in suitable containers). A total of 319 (76.1%) clinicians agreed that all these procedures should be adopted. In clinical practice, however, obstetricians declared that the use of latex gloves and collecting needles in suitable containers were always adopted, 'washing hands after using gloves' less frequently, and other procedures such as protective impermeable garments, glasses and mask were infrequently applied.
Adult↗
In vivo effects of human follicle-stimulating hormone-related synthetic peptide hFSH-beta-(81-95) and its subdomain hFSH-beta-(90-95) on the mouse estrous cycle.
We have previously reported that a synthetic peptide corresponding to amino acid residues 81-95 of the human (h) FSH-beta subunit inhibited binding of [125I]hFSH to bovine calf testis membranes and stimulated estradiol biosynthesis in primary cultures of rat Sertoli cells. We have now obtained several lines of evidence demonstrating in vivo effects of hFSH-beta-(81-95) on the mouse estrous cycle. 1) A single i.p. injection of 200 micrograms/g BW hFSH-beta-(81-95) significantly (p < 0.001) prolonged vaginal estrus in comparison to that in vehicle-injected control mice. 2) Vaginal smears taken at estrus from mice given hFSH-beta-(81-95) were characterized by the complete absence of epithelial casts, a hallmark of spontaneous ovulation in mice. 3) Mice receiving hFSH-beta-(81-95) had significantly (p < 0.001) lower serum estradiol at proestrus and serum progesterone at diestrus than vehicle-injected control mice. 4) The proestrous effects of estrogen on uterine ballooning and weight gain, clearly evident in vehicle-injected control mice, were not observed in mice treated with hFSH-beta-(81-95). A synthetic peptide corresponding to the carboxy-terminal region of hFSH-beta-(81-95), hFSH-beta-(90-95), inhibited binding of [125I]hFSH to bovine calf testis membranes, antagonized FSH-stimulated estradiol biosynthesis by primary cultures of rat Sertoli cells, and prolonged vaginal estrus in normally cycling mice. A synthetic peptide corresponding to the amino-terminal domain, hFSH-beta-(81-86), was inactive in vitro and had no effect on the mouse estrous cycle. The results of the present study provide additional evidence for in vivo effects of FSH-related synthetic peptides.
Animals↗
Exposure to video display terminals and risk of spontaneous abortion.
Clusters of spontaneous abortion among video display terminal (VDT) users in North America and Canada in the late 1970s aroused suspicion about the potential risk of an association between VDT. exposure and pregnancy outcome. This case-control study considered the association between VDT use and the risk of miscarriage. Cases were 508 women admitted for spontaneous abortion to the Clinica Luigi Mangiagalli and a network of obstetric departments in the Milan area. Controls were 1,148 women who gave birth at term to healthy infants on randomly selected days at the same hospitals where cases were identified. No association emerged between VDT exposure and spontaneous abortion, the estimated odds ratio being 1.0 (95% CI: 0.8-1.2). This evidence agrees with studies conducted in different countries by various authors.
Abortion, Spontaneous↗
Hepatic and associated response of rats to pregnancy, lactation and simultaneous treatment with butylated hydroxytoluene.
This paper describes changes in the livers of rats fed diets containing butylated hydroxytoluene (BHT) over two generations in two separate studies. BHT did not produce tumours when tested for carcinogenicity in several studies by the conventional way. However, when BHT was given to rats in a two-generation carcinogenicity study, a high incidence of hepatic tumours was found in males but not in female rats of the F1 generation. A sequential study has been carried out to gain an insight into this unexpected finding, paying particular attention to the perinatal period. In the dose-ranging study designed to assess the tolerance of rats to BHT, groups of male and female rats (F0 generation) were fed diets calculated to deliver 0, 500, 750 and 1000 mg/kg body weight/day. Following a loading period of 5 wk the rats were mated. The BHT content of the diet was not adjusted during pregnancy and lactation. Owing to the normal increase in food consumption during lactation, intakes peaked at double the nominal value by 21 days after the birth of pups. At this time the pups (F1) were weaned onto control diet and maintained on it for 4 wk. At birth, the body weights of pups from the BHT-treated dams were comparable to those of the controls but at weaning the body weights of the pups from all three dose levels were less than those of the controls. At the termination of the experiment (4 wk after weaning), the pups from BHT-treated dams still weighed less than those from untreated controls. In the main experiment the F0 generation were fed 0, 25, 100 and 500 mg/kg body weight/day. Their offspring (F1 generation) were weaned on diets containing the same amount of BHT as the respective parents, apart from the group given the highest dose level (500 mg/kg body weight/day). This dose level was reduced to 250 mg/kg body weight/day at weaning in order to conform with previously published findings. The pups from the dams given the highest dose level were maintained on a dietary concentration of 250 mg/kg body weight/day for the entire study. A group of age-matched non-pregnant females was also studied and the results obtained compared with those from pregnant dams. Pups from all groups were examined at day 20 of gestation, at weaning (21 days after birth), and at 4 and 22 wk post-weaning. There were no effects on fertility and no increase in foetal abnormalities at any dose of BHT. Dams receiving BHT at a nominal dose of 500 mg/kg body weight/day showed liver enlargement accompained by induction of pentoxyresorufin O-depentylase and glutathione S-transferase, and proliferation of the endoplasmic reticulum. Pups from these dams were of the same weight at birth as controls but lost weight during the lactation period. This deficit was not recovered by the time the experiment was terminated. Hence, in two independent studies, the only significant finding in rats treated with BHT in utero and during lactation was that the weight gain of pups during lactation was less than expected when dams received at least 500 mg BHT/kg body weight/day. The body weight of pups did not return to normal following a return to a control diet for 4 wk. It is postulated that the retardation in weight gain of the pups could be due to inadequate milk production.
Animals↗
A synthetic peptide corresponding to amino acid residues 34 to 37 of human follicle-stimulating hormone beta-subunit accelerates the onset of puberty in male and female mice.
We have previously reported that a synthetic peptide amide corresponding to residues 34-37 (TRDL, threonine, arginine-aspartic acid-leucine) of the beta-subunit of human FSH induced prolonged vaginal estrus in normally cycling female mice (see Ref. 15). These results represented the first demonstration of an in vivo effect of a gonadotropin-related synthetic peptide on reproductive processes. We have extended these studies to examine possible effects of TRDL on the onset of puberty in female mice. In two replicated experiments, vehicle-injected control mice attained first vaginal estrus by day 39. An ip injection of 200 ug TRDL/g BW to 28-day-old prepubertal female mice, however, accelerated the onset of first vaginal estrus by 7 days in 11 of 12 (11/12) (Exp 1) and 7/9 (Exp 2) mice. Serum estradiol levels were significantly (P = 0.017) elevated in TRDL-treated mice, whereas progesterone was unchanged. Uteri of TRDL-treated mice were significantly (P = 0.003) heavier than uteri of vehicle-injected control animals of the same age and body weight. Intraluminal fluid accumulation (ballooning) at proestrus was absent in 20/21 TRDL-treated females, as were oviductal ova and ovarian corpora lutea. These phenomena are characteristic of the first estrous cycles of female mice isolated from males. To obtain further evidence for in vivo effects of TRDL, we assessed the ability of TRDL to accelerate the onset of puberty in male mice. When given as five consecutive daily ip injections of 200 ug/g BW to 28-day-old prepubertal male mice, TRDL significantly increased testis weight, when compared with vehicle-injected control mice of the same age and BW (171.3 +/- 3.8 mg vs. 151.6 +/- 4.3 mg, P = 0.001) and induced a 6.5-fold increase in serum testosterone levels. These studies confirm the previously reported in vivo activity of a synthetic peptide corresponding to human FSH-beta subunit 34-37 (TRDL) in adult female mice and extend its effects to the acceleration of the onset of puberty in immature male and female mice.
Amino Acids↗
In vivo effects of leptin-related synthetic peptides on body weight and food intake in female ob/ob mice: localization of leptin activity to domains between amino acid residues 106-140.
In C57BL/6J ob/ob mice, a single base mutation of the ob gene in codon 105 results in the replacement of arginine by a premature stop codon and production of a truncated inactive form of leptin. These observations suggest that leptin activity may be localized, at least in part, to domains distal to amino acid residue 104. To investigate this possibility, we synthesized six overlapping peptide amides corresponding to residues 106-167 of leptin, and examined their effects on body weight and food intake in female C57BL/6J ob/ob mice. When compared with vehicle-injected control mice, weight gain by mice receiving 28 daily 1-mg i.p. injections of LEP-(106-120), LEP-(116-130), or LEP-(126-140) was significantly (P < 0.01) reduced with no apparent toxicity. Weight gain by mice receiving LEP-(136-150), LEP-(146-160), or LEP-(156-167) was not significantly different from that of vehicle-injected control mice. The effects of LEP-(106-120), LEP-(116-130), or LEP-(126-140) were most pronounced during the first week of peptide treatment. Within 7 days, mice receiving these peptides lost 12.3%, 13.8%, and 9.8%, respectively, of their initial body weights. After 28 days, mice given vehicle alone, LEP-(136-150), LEP-(146-160), or LEP-(156-167) were 14.7%, 20.3%, 25.0%, and 24.8% heavier, respectively, than they were at the beginning of the study. Mice given LEP-(106-120) or LEP-(126-140) were only 1.8% and 4.2% heavier, respectively, whereas mice given LEP-(116-130) were 3.4% lighter. Food intake by mice receiving LEP-(106-120), LEP-(116-130), or LEP-(126-140), but not by mice receiving LEP-(136-150), LEP-(146-160), or LEP-(156-167), was reduced by 15%. The results of this study indicate 1) that leptin activity is localized, at least in part, in domains between residues 106-140; 2) that leptin-related peptides have in vivo effects similar to those of native leptin; and 3) offer hope for development of peptide analogs of leptin having potential application in human or veterinary medicine.
Amino Acid Sequence↗