Male Litter Research Articles

Chronic exposure to inorganic arsenic and fluoride induces redox imbalance, inhibits the transsulfuration pathway, and alters glutamate receptor expression in the brain, resulting in memory impairment in adult male mouse offspring

Exposure to toxic elements in drinking water, such as arsenic (As) and fluoride (F), starts at gestation and has been associated with memory and learning deficits in children. Studies in which rodents underwent mechanistic single exposure to As or F showed that the neurotoxic effects are associated with their capacity to disrupt redox balance, mainly by diminishing glutathione (GSH) levels, altering glutamate disposal, and altering glutamate receptor expression, which disrupts synaptic transmission. Elevated levels of As and F are common in groundwater worldwide. To explore the neurotoxicity of chronic exposure to As and F in drinking water, pregnant CD-1 mice were exposed to 2 mg/L As (sodium arsenite) and 25 mg/L F (sodium fluoride) alone or in combination. The male litter continued to receive exposure up to 30 or 90 days after birth. The effects of chronic exposure on GSH levels, transsulfuration pathway enzymatic activity, expression of cysteine/cystine transporters, glutamate transporters, and ionotropic glutamate receptor subunits as well as behavioral performance in the object recognition memory task were assessed. Combined exposure resulted in a significant reduction in GSH levels in the cortex and hippocampus at different times, decreased transsulfuration pathway enzyme activity, as well as diminished xCT protein expression. Altered glutamate receptor expression in the cortex and hippocampus and decreased transaminase enzyme activity were observed. These molecular alterations were associated with memory impairment in the object recognition task, which relies on these brain regions.

LACTATIONAL EXPOSURE OF METHOXYCHLOR IMPAIRS SPERM QUALITY IN BALB/C MICE

Numerous pesticides derived from human activity are now disseminated in the environment that have been identified as an estrogenic activity that mainly affects the male reproductive system. The objective study was to determine the dose of methoxychlor (MXC) pesticides administered to the mother during the lactation period that would affect the sperm quality of the offspring in mice. Twenty-four BALB/c strains were divided into control and treatment groups. MXC was administered once daily by intraperitoneal to female mice for days 1 to 21 of lactation periods, with 0.14 mg/g, 0.28 mg/g, and 0,42 mg/g doses of MXC. Male litters were killed at postnatal day (PND) 60, and the cauda epididymis was used to observe sperm motility and morphology characteristics. Parameters observed were the number of spermatozoa abnormal and the percentage of progressive spermatozoa. ANOVA showed that the effect of MXC was significantly different in the case of the number of abnormal sperm and the rate of progressive sperm parameters. Duncan's Multiple Range Test (DMRT) showed that D3 (0.42 mg/g) gave the highest effect of MXC on increasing abnormal spermatozoa morphology and decreasing the percentage of motile sperm. These results indicate that exposure to MXC, which showed a physiological response in the lactation period, reduces the sperm quality of offspring

Relationships between litter size, sex ratio and within-litter birth weight variation in a sow herd and consequences on weaning performance.

Routine selection for litter size has resulted in an increase in the proportion of lightweight piglets. There is a need to balance prolificacy with litter uniformity to maximize profit. A total of 3,465 piglets from 310 litter records obtained from 2016 until 2019 at the Pig Industry Board research unit, Arcturus, Zimbabwe were used to determine the relationships between litter size, sex ratio, and within-litter birth weight variation in the sow herd and consequences on performance at weaning. The regression procedure of SAS was used to determine the relationships between litter size, sex ratio, and within-litter birth weight variation. The regression procedure was also used to determine the relationships between number born alive, within-litter birth weight variation, and sex ratio, and litter performance traits at weaning. Parity of sow, year, and month of farrowing did not affect sex ratio (P > 0.05). The number born alive and number of piglets born had no relationship with sex ratio (P > 0.05). As the sex ratio increased, percent survival of piglets at weaning also increased linearly (P < 0.05). As the proportion of males in litters increased, within-litter birth weight variation and within-litter weaning weight variation increased reaching maximum as the proportion of males in litters approached 0.5 and then decreased onwards. As the proportion of males in litters approached 1, within-litter birth weight variation and within-litter weaning weight variation reached their least values. In conclusion, within-litter sex ratio does not vary with parity, year, and month of farrowing. Within-litter weight variation is highest in litters with equal number of male and female piglets and lowest in unisex litters. This implies that the production of unisex litters can help to reduce the variation in the weight of pigs at birth, weaning, and marketing which is one of the biggest economic challenges faced by pork producers.

Gestational Monosodium Glutamate Exposure Effects on Anogenital Distance of Male Rat Pups

High-dose Monosodium Glutamate (MSG) expo sure increases the estrogen level in pregnant rats. However, there are limited data available on whether the MSG-related maternal hormonal effects can affect male litters' genitalia phenotype. This study aimed to analyze the impact of MSG on estrogen level in pregnant rats and anogenital distance in male pups. Experiment for this study was performed at the animal facility of Biomedical Laboratory at the Faculty of Medicine, Universitas Andalas, from April 2019 to February 2020. Pregnant Wistar rats were given MSG orally at 2 and 4 mg/g body weight (BW) for 20 days. On day 21, pregnant rats were sacrificed and blood was drawn intracardially. Estradiol serum level was measured by ELISA. Male pups were counted, and the anogenital distance (AGD) was measured. Maternal serum estradiol levels were statistically analyzed by One-Way ANOVA and the AGD of male litters were analyzed by the Kruskal-Wallis test. Results showed that perinatal MSG exposure increased the estradiol level (26.3±4.5 pg/ml; 37.5±6.7 pg/ml; 62.1±8.2 pg/ml in control, 2 mg/g BW, and 4 mg/g BW group, respectively [mean±SD; p=&lt;0.001]) and decreased the AGD (4 mm; 3 mm; 1.5 mm in control, 2 mg/g BW, and 4 mg/gBW group, respectively [median; p=&lt;0.01]) in a dose-dependent manner. Thus, MSG exposure during pregnancy is a risk factor for male rat feminization.

Maternal age, paternal age, and litter size interact to affect the offspring sex ratio of German Shepherd dogs

Several factors influence mammalian sex ratio. In this study, the effects of parental age and litter size on the offspring sex ratio in dogs were evaluated in 602 puppies born from 101 German Shepherd litters from a breeding facility. The data was obtained from recordings of the kennel and Studbook from 1996 to 2016. A linear mixed-model analysis was performed using dam age, sire age and litter size as predictors of the percentage of males in litter. Dam age and litter size has direct effect on sex ratio. Dam age * sire age and dam age * litter size interactions are significant. When evaluating dam age by sire age, the expected male percentage in the litter is higher for old dams mated with young sires and young dams mated with old sires. Smaller percentage of males is expected for young dams mated with young sires and old dams mated with old sires. When evaluating dam age by litter size, the expected percentage of males in the litter is higher for young dams delivering big litters and old dams delivering small litters. Smaller percentage of males is expected for young dams delivering small litters and old dams delivering big litters. Dam aging increased proportion of males in litters. We concluded that offspring sex ratio is determined partially by the dam age, sire age and litter size interactions in German Shepherd dogs.

The Effect of Prenatal and Postnatal Administration of Manganese Chloride on the Developing Caudate Nucleus of the Corpus Striatum in Male Albino Rats and the Possible Beneficial Role of Vitamin E Supplementation: A Histological and Immunohistochemical study

Background: Although low levels of manganese (Mn) intake are necessary for human health but may also be toxic at high concentrations. Infants are subjected to risk of elevated Mn exposure from soy-based infant formulas and contaminated well-water which contain Mn at high levels. Young children are susceptible to be exposed to an elevated Mn levels because the developing brain is vulnerable to the chemical insult, as well as an increased absorption and retention of ingested Mn in comparison to the adults. Vitamin E is an antioxidant and is protectective to the biological membranes from oxidative stress.Aim of work: To investigate the effect of adminstration of manganese chloride (MnCL2) during pregnancy and lactation on the postnatal development of the caudate nucleus of the rat corpus striatum and to evaluate the role of vitamin E. Also, this work aimed to detect the effect of MnCL2 withdrawal..Material and Methods: Forty-pregnant female albino rats were divided into two equal groups (20 rats each): group I (control) and group II (MnCl2-treated). Litters of the control dams were sacrificed at the age of one day (group Ia), 10 days (group Ib), 20 days (group Ic) and 2 months (group Id). MnCl2-treated dams received MnCl2 at a dose of 50 mg /kg b.w. orally daily throughout conception till 20th day postnatally. Half of their male litters were sacrificed at the age of one day (group IIa), 10 days (group IIb) and 20 days (group IIc). The other half was sudivided at the age of 20 days into 3 equal groups: group IId received the same dose of MnCl2 till the age of 2 months, group IIe received vitamin E at a dose of 48 mg/kg b.w. orally daily till the age of 2 months concomitantly with MnCl2 and group IIf received distilled water orally daily till the age of 2 months. Animals in the previous three groups were sacrificed at the age of 2 months. Brains were processed to be studied using Einarson’s gallocyanin stain, H&E, transmission electron microscopy and immunohistochemical study for glial fibrillary acidic protein (GFAP).Results: As regard the postnatal development of the caudate nucleus, there was a gradual increase in the amount of Nissl's granules and the size of the neuronal nuclei with the presence of an apparent decrease in neuronal density. A gradual increase in the density of GFAP positive cells was noticed. Maternal MnCl2 administration affected the development of the caudate of the offsprings at the different ages studied. Many cells revealed degenerative changes in the form of darkly stained pyknotic or irregular rarified nuclei and vacuolated cytoplasm. There was progressive reduction in the amount of Nissl's granules. More abundant GFAP positive cells were noticed comparable to those in the control ages. On electron microscopic study, there were dark degenerated cells and deformed myelin sheath with splitting and fragmentation of their lamellae. Swollen mitochondria with disrupted cristae were noticed in the cytoplasm of many cells. These histological and immunohistochemical changes were found to be corrected with the administration of vitamin E and the cells had nearly normal appearance. These changes revealed no improvement on withdrawal of MnCl2 and it is nearly like that under usage.Conclusion: Gestational and lactational administration of MnCl2 had harmful effects on the structure of the caudate nucleus of the offsprings at different ages. Vitamin E can be used for prevention and treatment of these effects as an adjuvant therapy.

Genetic analysis of teat number in pigs reveals some developmental pathways independent of vertebra number and several loci which only affect a specific side

BackgroundNumber of functional teats is an important trait in commercial swine production. As litter size increases, the number of teats must also increase to supply nutrition to all piglets. Therefore, a genome-wide association analysis was conducted to identify genomic regions that affect this trait in a commercial swine population. Genotypic data from the Illumina Porcine SNP60v1 BeadChip were available for 2951 animals with total teat number (TTN) records. A subset of these animals (n = 1828) had number of teats on each side recorded. From this information, the following traits were derived: number of teats on the left (LTN) and right side (RTN), maximum number of teats on a side (MAX), difference between LTN and RTN (L − R) and absolute value of L − R (DIF). Bayes C option of GENSEL (version 4.61) and 1-Mb windows were implemented. Identified regions that explained more than 1.5% of the genomic variation were tested in a larger group of animals (n = 5453) to estimate additive genetic effects.ResultsMarker heritabilities were highest for TTN (0.233), intermediate for individual side counts (0.088 to 0.115) and virtually nil for difference traits (0.002 for L − R and 0.006 for DIF). Each copy of the VRTN mutant allele increased teat count by 0.35 (TTN), 0.16 (LTN and RTN) and 0.19 (MAX). 15, 18, 13 and 18 one-Mb windows were detected that explained more than 1.0% of the genomic variation for TTN, LTN, RTN, and MAX, respectively. These regions cumulatively accounted for over 50% of the genomic variation of LTN, RTN and MAX, but only 30% of that of TTN. Sus scrofa chromosome SSC10:52 Mb was associated with all four count traits, while SSC10:60 and SSC14:54 Mb were associated with three count traits. Thirty-three SNPs accounted for nearly 39% of the additive genetic variation in the validation dataset. No effect of piglet sex or percentage of males in litter was detected, but birth weight was positively correlated with TTN.ConclusionsTeat number is a heritable trait and use of genetic markers would expedite selection progress. Exploiting genetic variation associated with teat counts on each side would enhance selection focused on total teat counts. These results confirm QTL on SSC4, seven and ten and identify a novel QTL on SSC14.

Atrazine contamination of sow feed and water affects the litter sex ratio and &#x0D; increases fetal mortality

Feed and water samples for 828 sows collected at weaning and weekly during gestation were assayed for atrazine content. Atrazine intake >3 µg d−1 resulted in reduced litter size and increased female:male litter sex ratio (P < 0.05). Of 1483 mummified fetuses, the majority of them were male (2.5:1), and mortality primarily occurred in weeks 7 and 8.

The Presence Of Strange Males' Odor Induces Behavioral Responses And Elevated Levels Of Low Molecular Weight Proteins Excreted In The Urine Of Mature Water Vole Males (Arvicola amphibius L).

We hypothesized that low molecular weight urinary proteins play a role in male-male chemical communication in the water vole, Arvicola ampibius L. We studied the effect of placing soiled litter from strange males into the cage of another sexually mature male on the intensity of its digging and scattering, urination on the litter, and alteration in the levels of low molecular weight proteins (15-25 kDa) excreted in the urine before and after 4 days of exposure as determined by chip electrophoresis. The intensity of digging and scattering was positively correlated with levels of testosterone in serum of males exposed to strange male odors (r = 0.56; P < 0.01), as well as with the concentration of low molecular weight proteins in the donor's urine (r = 0.52, P < 0.05). At the end of the experiment, the level of low molecular weight protein in excreted urine was elevated in the males exposed to the strange male's litter. These results highlight the importance of quantitative inter-individual variation of low molecular weight urinary proteins in the modulation of the physiology and behavior of conspecifics.

The Effect of Prenatal Exposure to Nicotine versus Thiocyanate on Pituitary-Testicular Axis of Juvenile Albino Rats: A Comparative Histological and Electron Microscopic Study

Cigarette smoking prevalence is still increasing in the developing world especially among men mainly in central Asia, east Europe and Africa. Furthermore, maternal cigarette smoking during pregnancy has multiple deleterious effects on the offspring, which may persist into adulthood. The present work aims at clarifying whether the prenatal exposure to either nicotine or thiocyanate could be the responsible factor in induction of the possible effect of smoking on spermatogenesis and the cytoarchitecture of the testis and hence influencing the male fertility later on. Twenty pregnant rats were randomly divided into four groups from gestational day 4. Groups Ia and b served as control. Group II animals were injected with nicotine (6 mg/kg/day) subcutaneously as a single dose. Group III Animals were treated with oral potassium thiocyanate (25 mg/rat/day) as a single dose through gastric gavages. Five male litters from each group (one/each pregnant rat) were sacrificed at the age of 1 month. Pituitary and testicular tissue samples were subjected to histological and electron microscopic study. The counts of different cells of seminiferous tubules were statistically analyzed for significance. Results revealed apoptotic changes at the subcellular level of the pituitary gonadotrophs and different spermatogenic and Sertoli cells of the testis. The number of Sertoli and different spermatogenic cells- rather than spermatogonia- showed a very highly significant decrease in the nicotine treated group in comparison to the control. The dense cells revealed a very highly significant increase in the nicotine treated group. In conclusion, the results of the present study were more consistent with a suggested dual effect of nicotine on the pituitary-testicular axis rather than a purely direct effect on the testis. On the other hand, thiocyanate induced subcellular effect on the testicular histology with minimal affection of gonadotrophs.

Does prenatal restraint stress change the craniofacial growth pattern of rat offspring?

A major and frequently encountered condition underlying the long-term programming effects of the intrauterine environment is exposure to stress. Gestational stress is an environmental factor that induces physical and behavioral alterations in offspring. Seventy female virgin Wistar rats were mated with one male rat for a maximum of four times, after which 52 pregnant rats were divided into two groups. In the experimental group the rats were exposed to restraint stress during pregnancy, whereas the control group did not receive the stress protocol. One male litter was randomly chosen from the offspring of each rat with 8-13 pups. A total of 40 male rat offspring were available for analysis. Thirty-one linear and angular measurements were analyzed in both study groups to investigate whether prenatal restraint stress changes the craniofacial growth pattern of rat offspring. In the prenatally stressed group, anterior cranial base length and viscerocranium measures were significantly increased compared with the control group, whereas cranial width, mandibular dimensions, and posterior cranial height and length remained unchanged. Furthermore, the prenatally stressed group showed backward rotation of the midface and decreased flattening of the cranial vault. It was concluded that prenatal chronic stress can induce alterations in the craniofacial growth pattern by promoting endochondral growth in the cranial base and nasal septum.

Mitochondria-targeted antioxidant SkQ1 accelerates maturation in Campbell dwarf hamsters (Phodopus campbelli).

We tested two hypotheses. 1) SkQ1 positively affects postnatal development of hamsters in litters born to parents receiving long-term SkQ1 treatment. 2) SkQ1 accelerates maturation of juvenile females receiving the antioxidant treatment from 10 days of age. Parental pairs were kept in an outdoor vivarium under conditions close to natural. At the age of 25 days, juvenile males in litters born to parents treated daily with SkQ1 (50 nmol/kg per os) had higher epididymis mass. Both the size of a litter and SkQ1 affected epididymis mass in young males. Both the litter size and SkQ1 affected uterus mass in 25-day-old females. Juvenile females who received SkQ1 treatment from 10 days of age demonstrated earlier opening of the vagina. This experiment was replicated with the same result. At the age of 2.5 months, virgin females treated with SkQ1 from the early age demonstrated higher ovary mass.

Postnatal early overnutrition dysregulates the intrarenal renin–angiotensin system and extracellular matrix-linked molecules in juvenile male rats

Overnutrition during the perinatal period has been associated with susceptibility to obesity and related comorbidities. We examined the effects of postnatal early overnutrition on the development of juvenile obesity and the associated renal pathophysiological changes. Three or 10 pups per mother from rat pup litters were assigned to either the overnutrition or control groups during the first 21 days of life. The effects of overfeeding were measured at 28 days. The smaller male litter pups were heavier than the controls between 4 and 28 days after birth (P<.05). By 28 days of age, the kidney weight per body weight ratio decreased in the small litter group (P<.05). Circulating leptin levels increased in the small litter rats (P<.05). Overnutrition had no effect on renal cell proliferation, apoptosis, macrophages and glomerulosclerosis. In the immunoblots and immunohistochemistry, renin and angiotensin II type (AT) 2 receptor expression increased in the overfed rats (P<.05). By contrast, the plasminogen activator inhibitor (PAI)-1 and matrix metalloproteinase (MMP)-9 expression decreased in the overnutrition group (P<.05). The AT 1 receptor, tissue inhibitor of MMP-1, monocyte chemoattractant protein-1, tumor necrosis factor-α, osteopontin and adiponectin expression was not changed. Our data showed that postnatal early overfeeding led to hyperleptinemia, juvenile obesity and the acquired reset of renal maturation. Up-regulation of renin and AT2 and down-regulation of PAI-1 and MMP-9 might contribute to abnormal programming of renal growth in rats exposed to postnatal early overnutrition.

Effect of sleep restriction during pregnancy on blood pressure and renal function of young offspring rats

Considering that changes at maternal environment have been associated to important abnormalities at the newborn, the aim of the present study was to examine the impact of sleep restriction during pregnancy on renal morphology and function in young offspring. Female 3 month-old Wistar rats were divided in three experimental groups: C (control), SR (sleep restriction between the 14th and 20th day of pregnancy) and SRT (sleep restriction during all the pregnancy). SR and SRT females were subjected to sleep restriction by the multiple platform technique for 20 hours daily. After birth, the offspring was reduced to 6 male litters per mother. The groups were designated OC (Control's offspring), OSR (SR's offspring) and OSRT (SRT's offspring). Blood pressure (BP) was measured by tail pletismography, at 2 and 3 months of age. Renal function parameters [renal plasma flow (RPF), glomerular filtration rate (GFR), sodium and potassium excretion and proteinuria] were studied at 3 months of age. Increased values of BP were observed in OSR and OSRT in comparison to OC [OSR:145±1.4 (43); OSRT:144±0.9 (68); OC:120±1.0 (45) mmHg, values measured at 3 months]. These groups also showed significant changes in RPF and GFR. Proteinuria was also increased in ORST in comparison to OC. Our present data suggest that changes at the maternal environment due to sleep restriction can result in hypertension and renal dysfunction in young offspring. Financial support: CNPq and FAPESP

Gene Expression, Function and Ischemia Tolerance in Male and Female Rat Hearts After Sub-Toxic Levels of Angiotensin II

To examine the response to chronic high-dose angiotensin II (Ang II) and a proposed milder response in female hearts with respect to gene expression and ischemic injury. Female and male litter–matched rats were treated with 400 ng kg−1 min−1 Ang II for 14 days. Hearts were isolated, subjected to 30-min ischemia and 30-min reperfusion in combination with functional monitoring and thereafter harvested for gene expression, WB and histology. Ang II-treated hearts showed signs of non-hypertrophic remodeling and had significantly higher end diastolic pressure after reperfusion, but no significant gender difference was detected. Ang II increased expression of genes related to heart function (ANF, β-MCH, Ankrd-1, PKC-α, PKC-δ TNF-α); fibrosis (Col I-α1, Col III-α1, Fn-1, Timp1) and apoptosis (P53, Casp-3) without changing heart weight but with 68% increase in collagen content. High (sub-toxic) dose of Ang II resulted in marked heart remodeling and diastolic dysfunction after ischemia without significant myocyte hypertrophy or ventricular chamber dilatation. Although there were some gender-dependent differences in gene expression, female gender did not protect against the overall response.

Sleep Restriction during Pregnancy: Hypertension and Renal Abnormalities in Young Offspring Rats

Because the maternal environment can affect several physiological functions of the newborn, the aim of the present study was to examine the impact of sleep restriction during pregnancy on renal morphology and function in young offspring. Female 3-month-old Wistar rats were divided in 2 experimental groups: C (control) and SR (sleep restriction between the 14th and 20th day of pregnancy). Pregnancy was confirmed by vaginal smear. SR females were subjected to sleep restriction by the multiple platform technique for 20 h daily. After birth, only male litters (6 for each mother) were selected and designated OC (offspring from C) and OSR (offspring from SR). At 2 months of age, blood pressure (BP) was measured by tail plethysmography; at 3 months the renal plasma flow (RPF), glomerular filtration rate (GFR), glomerular area, and number of glomeruli per mm3 were evaluated. Offspring from SR had higher systolic blood pressure than OC. In this group (OSR), we also observed significant increase in RPF and GFR, enlarged glomeruli diameter, and reduced number of glomeruli per mm3 of renal tissue. Our data suggest that sleep restriction during pregnancy is able to modify renal development, resulting in morphologic and functional alterations in young offspring.

Impact of gestational and lactational phthalate exposure on hypothalamic content of amino acid neurotransmitters and FSH secretion in peripubertal male rats

This study investigated the effect of the pre- and perinatal exposure to di-(2-ethylhexyl) phthalate (DEHP) on the neuroendocrine parameters that regulate reproduction in peripubertal male rats. DEHP at dose of 3 and 30 mg/kg bw/day was administered orally to female rat since pregnancy onset until weaning. The male litters were sacrificed at 30 days of age to determine gonadotropin serum level and the hypothalamic contents of the amino acids aspartate and gamma-aminobutyric acid. No changes in gonadotropin, aspartate and gamma-aminobutyric acid levels were detected at the low dose. DEHP 30 mg/kg bw/day reduced testis weight and serum FSH, in correlation with a significant increase in the inhibitory GABAergic tone and a reduction in the stimulatory effect of aspartate on gonadotropin level. This study provides unknown data regarding changes in the hypothalamic contents of the amino acid neurotransmitters, which are involved in the neuroendocrine regulation of reproductive axis, in peripubertal male rat offspring from dams exposed to DEHP during gestational and lactational periods. This could be related with the gonadotropin modifications also here described.

Impact of the UV-B filter 4-(Methylbenzylidene)-camphor (4-MBC) during prenatal development in the neuroendocrine regulation of gonadal axis in male and female adult rats

4-(Methylbenzylidene)-camphor (4-MBC), a UV-B ray filter, is an endocrine disruptors (ED). Our goal was to study the effect of 4-MBC on the neuroendocrine parameters that regulate reproduction in adult female and male rats that received this disrupter during prenatal development. The 4-MBC was administered (sc) to female rats (FO) since pregnancy onset, in doses of 100 mg/kg every other day. The litters (F1) were sacrificed at 70 days to determine gonadotrophin serum levels and also GnRH and the amino acids glutamate, aspartate and GABA release from the hypothalamus. The male litter rats (F1) present at adult age a decrease in serum LH and FSH concentration and so also GnRH, excitatory amino acids and GABA hypothalamic secretion. The female litters (F1) rats present at adult age an increase in serum LH and FSH concentration, whereas hypothalamic GnRH release was not modified. In these animals a significant increase of hypothalamic aspartate release as well as GABA secretion decrease were observed. Glutamate secretion was not modified. All these changes were accompanied by an advance (3 days) on the vaginal opening in 4-MBC rats group. In conclusion, prenatal administration of 4-MBC disrupts the gonadal axis in a sexual dimorphic mode that could be connected with the physiological sexual differences in the development of gonadotrophin secretion hypothalamic control mechanisms.

Effects of realimentation on small intestinal morphology and disaccharidase activity in malnutrition Sprague-Dawley rats

Low birth-weight infant and intrauterine growth retardation are still a health problem, especially in Indonesia due to high prevalence and need to be reduced. Malnutrition in infants are most common occur in low birth-weight infants. Malnutrition in rats resulted in hypotrophic and normoplastic mucosa of the small intestine. The finding was not only showed that small intestine was able to maintain its cell number in condition with restriction nutrient, however also suggested the posibility of epithelial regeneration if given adequate nutrient intake. Did realimentation recover the hypotrophic normoplastic mucosa to normotrophic normoplastic? The study aim to answer that question. Experimental animal study with post test-control group design was performed using 40 male litter of Sprague-Dawley rats, was fed standard chow. The study was divided into phases prenatally-induced malnutrition and continued with phase realimentation. The result of this study is the body weight, mucosal thickness, villus height, cryptus depth, ratio of villus/ crypt, number of villi, protein content, and disaccharidases of rats realimentation group was higher than non-realimentation group, but lower than control group. Prenatally-induced malnutrition did not reduced the population of small intestinal enterocytes. Realimentation in rats in prenatally-induced malnutrition was able to improve the hypotrophy of small intestinal mucosa and to increase the disaccharidases activities but did not reach the normal values. Realimentation in rats in prenatally-induced malnutrition was able to improve the maturity of small intestine mucosa but did not reach the normal values. The information will be helpfull to decide the policy of maternal malnutrition. (Med J Indones 2006; 15:208-16) Keywords : small intestinal morphology, disaccharidase activity, Sprague-Dawley rats, prenatally-induced malnutrition, realimentation.

Reproduction and demography of the northern quoll, Dasyurus hallucatus, in the lowland savanna of northern Australia

Reproduction and demography of the northern quoll, Dasyurus hallucatus, was assessed using live-trapping and radio-tracking at a lowland savanna site in Kakadu National Park between 1992 and 1995. Northern quolls were found to exhibit a highly synchronous breeding cycle with mating occurring late May/early June. The greatest peak in apparent male abundance was during the mating season, but this was probably due to their increased mobility at this time. Males demonstrated complete post-mating mortality, with most males dying within two weeks of mating. Young were born in mid to late June with the mean initial litter size for 8-teated females being 7.3. First-year mothers were more likely to have predominantly male litters, whereas second-year mothers had more females. The survival rate of pouch young was high but, once young were left in the den, survival was poor. Peaks in abundance for both sexes occurred when the juveniles first entered the trappable population in November each year. Mortality of females was high, with only 27% of females surviving to wean a second litter, and none bore a third. The most common proximate cause of adult mortality was predation. Increased predation pressure on adults, in particular due to a reduction in shelter and ground cover from too-frequent fire may make northern quolls vulnerable to local extinction in lowland savanna.