Maternal treatment with oleoyl-estrone induces resistance to lipid accrual in their descendants

Objective: To determine whether treatment of rat dams with oleoyl‐estrone (OE) has an effect on the offspring's long‐term response to diet restriction during lactation. Methods and Procedures: Control, OE‐treated, and diet‐restricted dams were treated up to day 15 of lactation. Changes in food intake and body weight were recorded for dams and their pups. After weaning, pups received a 4‐week standard diet followed by a 4‐week period of high‐fat diet. Lipid, protein, and energy content of pups plus energy intake and efficiency. Serum metabolites (glucose, urea, and cholesterol) and serum hormones (adiponectin, leptin, insulin, and sexual hormones). Results: Neither pups from dams in the OE‐treated nor in the diet‐restricted group showed significant changes in weight, though these two groups ingested 79% of food ingested by controls. At weaning, the pups from OE‐treated rats were smaller than those of the control or diet‐restricted groups. These pups maintained the differences in size and lipid content during the 4‐week standard‐diet period, whereas pups from diet‐restricted dams showed a sharp decrease in their lipid content. During the 4 weeks of high‐fat diet, the male offspring from OE‐treated dams increased the difference in lipid content in relation to the pups from control dams whereas in females the differences decreased. Female offspring from diet‐restricted dams showed the most marked changes in metabolite and hormone levels in relation to controls. Discussion: Treatment of lactating dams with OE programs the metabolic response of their offspring to resist the challenge of a high‐fat diet that would lead to obesity in adulthood.     

Early weaning programs rats to have a dietary preference for fat and palatable foods in adulthood

The objective of this work was to study the effect of early weaning on alimentary preference for the macronutrients protein, carbohydrate and fat in adult rats. Male Wistar rat pups were weaned by separation from the mother at 15 (D15) or 30 (D30) days old. Body weight and food intake were measured every 30 days until pups were 150 days old. At 110 days of age, the alimentary preference was evaluated for 1 h on 3 consecutive days. At 120 days of age, the palatable diet test was conducted during 3 consecutive 24-h periods. Body weight and food intake were not altered, but early weaning in rats induced an alimentary preference to fat and hyperphagia of a palatable diet. In conclusion, early weaning, although did not modify body weight or basal food intake, promoted an increased preference for palatable and fatty foods. This demonstrates that early weaning is not capable of promoting perceptible alterations of alimentary behavior under normal laboratory conditions. However, in the presence of a stimulating factor such as a choice of nutrients or a palatable diet, a possible latent effect on dietary preferences may become apparent. Over the long term, this preference for foods with high caloric density can lead to obesity and metabolic perturbations.     

Effect of moderate protein deficiency on reproduction in the female rat and on the development of the pups until weaning

Two groups of Wistar female rats were respectively fed ad libitum a standard stock diet containing 22 p. 100 protein (n = 93) and a diet containing 7.5 p. 100 protein (n = 189) for 8 weeks. They were mated with male rats of the same strain after 2 weeks of these diets. A small decrease (8 p. 100) in fecundity was observed but this moderate protein deprivation did not affect either the litter size (9.68 +/- 3.50 vs 9.61 +/- 3.69) or the percentage of stillborn pups (4.8 vs 4.9 p. 100). The postnatal mortality of the pups of deprived dams was much higher than that of pups from normal dams (11.2 vs 0.9 p. 100). During the suckling period, the 7.5 p. 100 protein diet did not cover the requirements of the dams. They lost 20 p. 100 of their weight, whereas the weight of the dams fed the 22 p. 100 protein diet remained stable. The weight deficit of the young rats born from deprived dams was about 10 p. 100 at birth but it rose to 50 p. 100 at weaning. During the gestation and suckling periods, the maternal body stores and tissues were mobilized to assure the growth of the young.     

Influence of maternal dietary calcium levels on milk zinc, calcium and phosphorus contents and milk production in rats

The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.     

Developmental changes of gut microflora and enzyme activity in rat pups exposed to fat-rich diet

The aim of this study was to investigate the effect of a high-fat (HF)/energy diet on the intestinal microbiota, the alkaline phosphatase (AP) activity, and related parameters of growth and obesity during the suckling and weaning periods in male Sprague-Dawley rats. From birth, nutrition in suckling pups was manipulated by feeding rat dams either HF or a standard diet, and then after weaning, by exposure of experimental pups to the HF, and control rats to normal diet. On days 15, 20, 40 the numbers of 2 microbial groups, i.e., Bacteroides/Prevotella (BAC) and the Lactobacillus/Enterococcus (LAB) in the jejunum, were determined by fluorescent in situ hybridization technique, and the AP activity was assayed histochemically. During all investigated periods HF pups gained body fat more rapidly than control animals, but from weaning they displayed significantly stunted growth resulting in final body weight loss. Obesity in HF rats was also accompanied by higher LAB and lower numbers of BAC and with permanently higher AP activity. Correlation of these data showed significant negative correlation between LAB, AP, and weight gain and energy efficiency, and significant positive correlation of BAC and AP activity with body fat. These data support the concept that postnatal nutritional experience represents an important factor affecting the ontogeny of intestinal microbial communities and intestinal function. These acquired changes could be a component of regulatory mechanisms involved in adverse and/or positive consequences of HF diet for adiposity, body weight, and energy-balance control in later life.     

Milk secretion in the rat: progressive changes in milk composition during lactation and weaning and the effect of diet.

1. Progressive changes in the composition of milk from rats has been studied from day 0 to 20 of lactation and for 3 days following separation of the dams and pups at day 20 post partum. 2. The changes in concentration of Na, K and lactose suggested that secretion both prepartum and following weaning occurred by a paracellular mechanism whereas a transcellular pathway existed during established lactation. 3. The concentration of total protein and casein increased gradually throughout lactation. In contrast, the concentration of serum albumin increased and transferrin decreased markedly during early lactation. The fat content of milk declined 3-fold within 5 days of birth but the concentration of Ca, Mg and inorganic P increased. The concentration of each of these milk constituents remained constant during established lactation. 4. Following weaning the pronounced decline in lactose, K and inorganic P was negatively correlated with an increase in all other milk constituents except fat. 5. Rats fed a low energy diet produced milk with a lower fat content but with an unaltered concentration of protein and carbohydrate. The growth rate of these litters was similar for the first 5 days of lactation when compared to litters from dams fed a high energy diet. The growth rate of litters thereafter and following weaning was greater for rats fed a high energy diet.     

Puberty onset in the female offspring of rats submitted to protein or energy restricted diet during lactation

This study aims to determine the effects of maternal protein and energy malnutrition during lactation on the linear growth, body weight and onset of puberty of the female offspring. At parturition, dams were randomly assigned to the following groups: (C) control group, with free access to a standard laboratory diet containing 23% protein; (PR) protein-restricted group, with free access to an isoenergy and protein-restricted diet containing 8% protein; and (ER) energy-restricted group, receiving standard laboratory diet in restricted quantities. After weaning, the female pups had free access to standard laboratory diet. From day 30 onwards, the pups were inspected daily for vaginal opening. Cyclic stages of the ovaries were studied by daily vaginal smears after vaginal opening until day 40 when all animals were sacrificed with pentobarbital. From day 4 after birth until day 40, body weight and linear growth in the PR and ER rats were significantly lower than in controls (p < 0.001). In spite of the significant (p<0.05) delayed in the vaginal opening in PR and ER rats, the first estrous cycle occurred at the same time of vaginal opening in all groups. The PR and ER rats exhibited a lower uterine (PR = 42%, ER = 40%, p < 0.001) and ovarian (PR = 26%, ER=19%, p < 0.05) absolute weight and uterus relative weight (PR = 27%, ER = 22%, p < 0.05). Our data showed that maternal protein and energy malnutrition during lactation leads to growth retardation and delayed on the onset of puberty in female pups, with vaginal opening and estrous cycle occurring at the same time.     

Chronic maternal dietary iodine deficiency but not thiocyanate feeding affects maternal reproduction and postnatal performance of the rat

Iodine deficiency disorders affect reproductive performance in the afflicted populations. Environmental iodine deficiency (ID) and goitrogens are important in their aetiology. We observed earlier that chronic maternal dietary ID but not goitrogen feeding altered the blood-brain barrier nutrient transport in adult rats. Whether similar differences exist in their effects on reproduction of dams and postnatal performance of the offspring has been assessed. Inbred, female, weaning WNIN rats were rendered hypothyroid by feeding for 8-12 weeks, a low iodine test diet or a control diet with added potassium thiocyanate (KSCN) (@ 25 mg/rat/day). Following mating with control males, they continued on their respective diets till their pups were weaned. Indices of reproductive performance such as percentage of conception, mortality of dams during pregnancy and parturition, litter size, and survival of pups till weaning were affected markedly by ID but not thiocyanate feeding. Neither ID nor thiocyanate feeding from conception or parturition affected their reproductive performance. Nevertheless, postnatal weight gain of pups was less in all the three ID groups but not thiocyanate fed dams. Rehabilitation of chronically ID pregnant dams from conception or parturition did not improve their pregnancy weight gain, litter size or birth weight of pups but decreased abortion and mortality of mothers during pregnancy and parturition. Rehabilitation improved the pups' postnatal weight gain but the effect was only moderate. Based on the results of the present study it may be suggested that maternal ID but not thiocyanate feeding affects reproductive performance and postnatal performance of their offspring.     

Development of hepatic and adipose tissue lipogenic enzymes and insulinemia during suckling and weaning on to a high-fat diet in Zucker rats

This study was designed to monitor the developmental changes in insulinemia and lipogenic enzyme activities in both inguinal adipose tissue and liver during suckling (7, 9, 14, and 17 days of age) and weaning (22 and 30 days of age) on to either a low-fat or a high-fat diet in lean (Fa/fa) and obese (fa/fa) rats. Tissues were removed through surgery and genotypes were retrospectively determined. During suckling, there was no difference in liver enzyme activities between the two groups. In contrast, adipose tissue fatty acid synthetase was increased by 50% and citrate cleavage enzyme and malic enzyme by 30% by 9 days of age. By 17 days of age, there was a threefold elevation in these enzyme activities and 6-phosphogluconic dehydrogenase and a twofold increase in glucose-6-phosphate dehydrogenase per inguinal fat pad in fa/fa versus Fa/fa. Consistent with these results, fat pad weight was increased by 20%, 50%, and 100% at 9, 14, and 17 days of age, respectively, in obese as compared to lean pups. However only by 17 days of age could a slight but significant increase in insulin level be detected in obese pups. Enlargement of inguinal fat pad accelerated after weaning on to a low-fat diet and still more after weaning on to a high-fat diet. Weaning on to a low-fat diet elicited an induction of hepatic lipogenic enzymes two or three times greater in fa/fa than in lean pups, while weaning on to a high-fat diet blunted the differences between genotypes. The lipogenic enzyme activities displayed per total inguinal fat were three to ten times greater in obese than in lean pups, regardless of the diet. However, adipose tissue lipogenic enzyme activities were much lower after weaning on to a high-fat than on to a low-fat diet in obese pups. The high-fat diet was as effective as the low-fat diet in triggering hyperinsulinemia in obese pups. The increased adipose tissue capacity for lipogenesis, starting during the suckling period, could play an important etiologic role in the development and maintenance of obesity in the Zucker rat.-Bazin, R., and M. Lavau. Development of hepatic and adipose tissue lipogenic enzymes and insulinemia during suckling and weaning on to a high-fat diet in Zucker rats.     

Differential Responses of Orexigenic Neuropeptides to Fasting in Offspring of Obese Mothers

Maternal obesity due to long‐term high‐fat diet (HFD) consumption leads to faster growth in offspring during suckling, and increased adiposity at 20 days of age. Decreased expression of the orexigenic neuropeptide Y (NPY) and increased anorexigenic proopiomelanocortin (POMC) mRNA expression were observed in the fed state. However, hunger is the major drive to eat and hypothalamic appetite regulators change in response to meals. Therefore, it is important to compare both satiated and fasting states. Female Sprague–Dawley rats (8 weeks old) were fed a cafeteria‐style HFD (15.33 kJ/g) or chow for 5 weeks before mating, with the same diet continuing throughout gestation and lactation. At postnatal day 20, male pups were killed either after overnight fasting or in the fed state. Pups from obese dams were hyperphagic during both pre‐ and postweaning periods. Pups from obese dams had higher hypothalamic mRNA expression of POMC and NPY Y1 receptor, but lower hypothalamic melanocortin‐4 receptor (MC4R) and its downstream target single‐minded gene 1 (Sim1), in the fed state. Overnight fasting reduced circulating glucose, insulin, and leptin and increased hypothalamic NPY Y1 receptor mRNA in pups from both lean and obese dams. Hypothalamic NPY and agouti‐related protein (AgRP) were only increased by fasting in pups from obese dams; reductions in MC4R and Sim1 were only seen in pups from lean dams. At weaning, the suppressed orexigenic signals in offspring from obese dams were normalized after overnight fasting, although anorexigenic signaling appeared impaired in these animals. This may contribute to their hyperphagia and faster growth.     

Long-term consequences of maternal high-fat feeding on hypothalamic leptin sensitivity and diet-induced obesity in the offspring

Epidemiological and animal studies suggest that the alteration of hormonal and metabolic environment during fetal and neonatal development can contribute to development of metabolic syndrome in adulthood. In this paper, we investigated the impact of maternal high-fat (HF) diet on hypothalamic leptin sensitivity and body weight gain of offspring. Adult Wistar female rats received a HF or a control normal-fat (C) diet for 6 wk before gestation until the end of the suckling period. After weaning, pups received either C or HF diet during 6 wk. Body weight gain and metabolic and endocrine parameters were measured in the eight groups of rats formed according to a postweaning diet, maternal diet, and gender. To evaluate hypothalamic leptin sensitivity in each group, STAT-3 phosphorylation was measured in response to leptin or saline intraperitoneal bolus. Pups exhibited similar body weights at birth, but at weaning, those born to HF dams weighed significantly less (-12%) than those born to C dams. When given the HF diet, males and females born to HF dams exhibited smaller body weight and feed efficiency than those born to C dams, suggesting increased energy expenditure programmed by the maternal HF diet. Thus, maternal HF feeding could be protective against adverse effects of the HF diet as observed in male offspring of control dams: overweight (+17%) with hyperleptinemia and hyperinsulinemia. Furthermore, offspring of HF dams fed either C or HF diet exhibited an alteration in hypothalamic leptin-dependent STAT-3 phosphorylation. We conclude that maternal high-fat diet programs a hypothalamic leptin resistance in offspring, which, however, fails to increase the body weight gain until adulthood.     

Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups

Dietary lipid quantity and quality have recently been shown to affect serum leptin levels in adult rats. Moreover, suckling pups from dams fed a high fat diet had increased serum leptin levels. The aim of the present study was to analyze the influence of essential fatty acid (EFA) deficiency on serum leptin levels in dams and their pups during the suckling period. For the last 10 days of gestation and throughout lactation, pregnant rats were fed a control or an EFA-deficient (EFAD) diet. The levels of leptin and EFA in the serum of the dams and pups were analyzed 1, 2, and 3 weeks after delivery. In parallel, serum levels of glucose and corticosterone were analyzed in the pups. Low serum leptin levels were found in the control lactating dams during the entire lactation period compared with the age-matched nonlactating animals. The leptin concentrations in the lactating dams fed the EFAD diet were lower compared with those fed the control diet. The serum leptin levels of suckling pups from dams on the EFAD diet were markedly decreased compared with controls (P < 0.05). The reduced serum leptin levels could not be explained by nutritional restriction as evaluated by serum levels of glucose and corticosterone. These results indicate the importance of the EFA composition of the maternal diet for serum leptin levels in both dams and pups. EFA deficiency in lactating dams may cause long-term effects on the pups through dysregulation of leptin and leptin-dependent functions. -- Korotkova, M., B. Gabrielsson, L. A. Hanson, and B. Strandvik. Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups. J. Lipid Res. 2001. 42: 359--365.     

Malnutrition during lactation changes growth hormone mRNA expression in offspring at weaning and in adulthood

Mothers' nutrition during lactation programs growth in their offspring. We studied the contribution of the growth hormone (GH) for this programming, evaluating GH mRNA expression. Lactating dams were grouped as follows: C, control diet with 23% protein; PR, 8% protein-restricted diet; and ER, energy-restricted diet, receiving the control diet in restricted quantities of the PR group's ingestion. Some pups were killed at weaning; the others received the control diet until they were sacrificed as adults. Pituitary GH mRNA was analyzed by Northern blot analysis. At weaning, the ER and PR animals had lower GH mRNA levels (-29% and -18%, respectively) and lower length as well as body weight. Ninety-day-old PR offspring showed a lower body length (-5%), whereas ER offspring showed a higher one (+5%); however, at 180 days, the lengths were not different. Both 90- and 180-day-old animals showed body weight differences against control animals, with PR offspring showing a lower (-10%) and ER offspring showing a higher (+12%) body weight. GH mRNA was higher in ER offspring at 90 and 180 days (+19% and +22%, respectively); it was lower in PR offspring at 90 and 180 days (-19% and -17%, respectively). Thus, we showed a direct relation between GH mRNA expression and length as well as body weight. We suggest that malnutrition during lactation may program GH mRNA expression patterns in adulthood and that these changes could be responsible for differences in growth patterns.     

Resveratrol attenuates oxidative stress and prevents steatosis and hypertension in obese rats programmed by early weaning

We hypothesized that resveratrol, a natural phytoalexin found in grapes, can prevent oxidative stress, obesity and its related disturbances in obese rats programmed by early weaning. Lactating Wistar rats were separated into two groups: early weaning (EW) — dams who were wrapped with a bandage to interrupt the lactation in the last 3 days of lactation; control — dams whose pups had free access to milk during all lactation. At the 150th day, EW offspring were randomly subdivided into EW+resveratrol (EW+Res) — resveratrol (30 mg/kg/day); EW+vehicle (EW) — rats that received 0.5% (w/v) aqueous methylcellulose. The control group received vehicle. Rats were treated by gavage daily for 30 days. EW offspring developed hyperphagia, higher body weight, visceral obesity, higher systolic (SBP) and diastolic blood pressure (DBP) (+15% and +20%, respectively; P<.05) and higher serum triglycerides (TG) and low-density lipoprotein but lower high-density lipoprotein (+55%, +33% and ?13%, respectively; P<.05). Resveratrol normalized food intake, SBP and DBP and prevented obesity and dyslipidemia in EW+Res. EW rats had higher plasma and liver thiobarbituric-acid-reactive substances (TBARS) and lower plasma superoxide dismutase (SOD) and liver glutathione peroxidase activities (+51%, +18%, ?58%, ?31%, respectively; P<.05), and resveratrol normalized both plasma and liver TBARS and increased the activity of SOD and catalase in plasma. EW rats presented liver steatosis and higher liver TG, and resveratrol prevented these hepatic alterations. In conclusion, this study demonstrated a potential therapeutic use of resveratrol in preventing obesity and oxidative stress and reducing the risk of hypertension, dyslipidemia and steatosis in adult rats programmed by early weaning.     

Maternal green tea extract supplementation to rats fed a high-fat diet ameliorates insulin resistance in adult male offspring

Maternal overnutrition is associated with increased risk of metabolic disorders in the offspring. This study tested the hypothesis that maternal green tea (GT) supplementation can alleviate metabolic derangements in high-fat-diet-fed rats born of obese dams. Female Sprague–Dawley rats were fed low-fat (LF, 7%), high-fat (HF, 30%) or HF diet containing 0.75% or 1.0% GT extract (GT1, GT2) prior to conception and throughout gestation and lactation. Both doses of GT significantly improved metabolic parameters of HF-fed lactating dams (P<.05). Birth weight and litter size of offspring from HF dams were similar, but GT supplementation led to lighter pups on day 21 (P<.05). The weaned male pups received HF, GT1 or GT2 diet (dam/pup diet groups: LF/HF, HF/HF, HF/GT1, HF/GT2, GT1/HF and GT2/HF). At week 13, they had similar weight but insulin resistance index (IRI), serum nonesterified fatty acid (NEFA) and liver triglyceride of rats born to GT dams were 57%, 23% and 26% lower, accompanied by improved gene/protein expressions related to lipid and glucose metabolism, compared with the HF/HF rats (P<.05). Although HF/GT1 and HF/GT2 rats had lower serum NEFA, their insulin and IRI were comparable to HF/HF rats. This study shows that metabolic derangements induced by an overnourished mother could be offset by supplementing GT to the maternal diet and that this approach is more effective than giving GT to offspring since weaning. Hence, adverse effects of developmental programming are reversible, at least in part, by supplementing bioactive food component(s) to the mother's diet.     

3,5,3'-Triiodothyronine administered to rat dams during lactation increases milk yield and triglyceride concentration and hastens pups growth

It is known that lactation induces a mild hypothyroid state in rats and other mammals while thyroid hormone administration increases milk secretion in ruminants. The aim of this study was to investigate the effects of a moderate dose of 3,5,3'-triiodothyronine (T3), administered to rat dams during lactation on pups' growth and milk yield and composition. Primiparous Wistar rats with litters adjusted to 10 pups per dam received either tap water or T3 (75 microg/kg x day) in their drinking water from parturition till weaning. Food and water intake of dams and body weight of dams and pups were measured daily. In other groups of rats with similar treatments, milk yield of dams, macronutrient milk composition, and mammary arteriovenous differences for triglycerides (TG) and glucose were also determined. Dams treated with T3 ingested more food and their pups gained more weight than controls. Milk yield, milk TG concentration and glucose extraction by mammary glands were also higher in T3 treated dams. The results show that compensation of the mild hypothyroidism of the lactating rat may contribute to an increase in milk production and lipid levels, leading to an increase in growth of pups.     

Effects of pre- and postnatal protein deprivation and postnatal refeeding on myenteric neurons of the rat large intestine: a quantitative morphological study

We investigated the effect of protein deprivation and refeeding on weight gain, the size of the colon, and the numbers and sizes of enteric neurons. Neurons were located by reduced nicotinamide adenine dinucleotide (NADH) diaphorase staining. Protein deprivation of the mother throughout pregnancy, and the mother and unweaned rat pups in the first 21 postnatal days, reduced the weights of pups to about 50% of control. The size of the colon was also reduced, by about 40%. Despite this, total numbers of neurons in the colon were not reduced. However, there was a small, but significant, 15% reduction in the areas of neuron profiles. After 21 days the remaining pups were removed from the mothers, and either maintained on the control diet, maintained on the protein-deprived diet, or changed from the protein-deprived diet to a normal diet (refed group). These rats were examined after a further 21 days. Refeeding restored body weight to 20% below control, restored colon size, and restored nerve cell size. After a total of 42 days of protein deprivation, nerve cell numbers were not significantly different from control. In undernourished rats at 21 and 42 days, neurons were less well stained than control for NADH diaphorase. Refeeding between 21 and 42 days restored the normal appearance of the neurons. It is concluded that enteric neurons are protected from loss even when there is a substantial reduction in body weight and organ size caused by protein deprivation. The neurons become smaller, but recover size after refeeding.     

Sniffing behaviour, copulatory readiness, copulatory performance and reproductive morphology of adult male rats weaned prematurely

Sexual behaviour of adult male rats weaned prematurely--on day 15 after birth--and of males weaned at the optimal age--on day 28--was compared at two life periods: at the age of 90 days and when the males were one year old. Sexual behaviour was evaluated by means of three characteristics: a) sniffing behaviour, b) copulatory readiness, c) copulatory performance. The differences in sniffing behaviour between prematurely and normally weaned males were assessed in terms of their responsiveness to sccents of unrelated adult males or oestrous females and from the point of view of both housing conditions after weaning and the animals' sexual experience. No differences were found in copulatory readiness as well as in copulatory performance between the two groups of males tested in their interaction with a female exhibiting complete precopulatory pattern. The morphological examination revealed no differences in the weight of reproductive organs and in spermatozoa development. We conclude that the sexual behaviour as well as reproductive organs of male rats are very resistant to early separation of pups from the mother which contrasts with some earlier findings.     

Rapid induction of vitamin A deficiency in rabbits

Clinical and biochemical evidence of vitamin A deficiency was produced in rabbits as early as 4-5 weeks after weaning to a vitamin A deficient diet from dams maintained during lactation on the deficient diet. Mean serum retinol levels at the time of weaning for the deficient dams were 25 +/- 6 micrograms/dl compared with 74 +/- 8 micrograms/dl for the controls. Five weeks after weaning, 25% of pups fed the vitamin A deficient diet had ocular lesions characterized by the accumulation of sloughed epithelium on the cornea. At this time, mean serum values of the pups were 10 +/- 4 micrograms/dl for the deficient group and 73 +/- 8 micrograms/dl for the controls. Evidence of critically depleted liver stores was documented in the deficient rabbits by an elevated relative dose response test (54 +/- 18%) that did not occur in the control group (6 +/- 5%). Although food consumption was similar, weight gain was lower in the deficient group when compared to the control group.     

Leptin serum concentration,food intake and body weight in rats whose mothers were exposed to malnutrition during lactation

We had shown that adult animals, whose mothers were submitted to protein or energy restriction during lactation, differ from controls in their body weight and thyroid function. The aim of this study was to evaluate, from birth through six months of age, leptin serum concentration, body weight and food intake in animals whose mothers received protein or energy restricted-diet during lactation as follows: control (C)-23% protein; protein-restricted (PR)-8% protein; energy-restricted (ER)-23% protein, in restricted quantity, according to the mean ingestion of the PR group. After weaning (day 21) all pups had free access the control diet. Body weight of pups from PR mothers were always lower than those from controls (p < 0.05), while body weight of pups from ER mothers surpassed that of the C group significantly at 140 days of age. The food intake was lower in both offspring from PR and ER mothers, normalizing on the 32th day in pups from ER mothers and on the 52th day in pups from PR mothers. Leptin serum concentration in both offspring from PR and ER mothers were significantly decreased on the 12th day (p < 0.05) and increased on the 21st day (p < 0.05) compared to control. After weaning there was no differences among the groups. It is possible that changes in leptin concentration during lactation in the offspring of malnourished groups could permanently modify the setpoint for body weight control.