The melatonin system is expressed in the ovine uterus: effect of the day of the oestrous cycle and undernutrition.

CONTEXT: Melatonin influences female reproduction, but expression of the melatonin system has not been characterised in the ovine uterus. AIMS: We aimed to determine whether synthesising enzymes (arylalkylamine N-acetyltransferase (AANAT) and N-acetylserotonin-O-methyltransferase (ASMT)), melatonin receptors 1 and 2 (MT1 and MT2), and catabolising enzymes (myeloperoxidase (MPO) and indoleamine 2,3-dioxygenase 1 and 2 (IDO1 and 2)), are expressed in the ovine uterus, and if they are influenced by the oestrous cycle (Experiment 1) or by undernutrition (Experiment 2). METHODS: In Experiment 1, gene and protein expression was determined in sheep endometrium samples collected on days 0 (oestrus), 5, 10 and 14 of the oestrous cycle. In Experiment 2, we studied uterine samples from ewes fed either 1.5 or 0.5times their maintenance requirements. KEY RESULTS: We have demonstrated the expression of AANAT and ASMT in the endometrium of sheep. AANAT and ASMT transcripts, and AANAT protein were more elevated at day 10, then decreased to day 14. A similar pattern was observed for MT2 , IDO1 , and MPO mRNA, which suggests that the endometrial melatonin system might be influenced by ovarian steroid hormones. Undernutrition increased AANAT mRNA expression, but seemed to decrease its protein expression, and increased MT2 and IDO2 transcripts, whereas ASMT expression was unaffected. CONCLUSIONS: The melatonin system is expressed in the ovine uterus and is affected by oestrous cycle and undernutrition. IMPLICATIONS: The results help explain the adverse effects of undernutrition on reproduction in sheep, and the success of exogenous melatonin treatments in improving reproductive outcomes.

Differential transcriptional responses underlie dietary induction of intestinal carbohydrase activities in house sparrow nestlings.

Many species show diet-induced flexibility of activity of intestinal enzymes; however, molecular and genetic mechanisms responsible for such modulation are less known, particularly in altricial birds. The goal of our study was to test whether a diet-induced increase in activity of intestinal maltase and sucrase in house sparrow nestlings is matched with an increase in maltase-glucoamylase (MG) and sucrase-isomaltase (SI) complex mRNAs respectively. Both enzyme activities were significantly higher in mid-intestine of nestlings fed a medium-starch (MS) diet compared to those fed a starch-free (SF) diet. In contrast to the similar pattern of dietary induction for both enzyme activities, diet MS elevated significantly only the level of MG mRNA, but not SI mRNA. The coordinated increase in activity of maltase and in MG mRNA is consistent with the hypothesis that dietary induction of this enzyme is under transcriptional control. In contrast, the lack of such coordination for changes in activity of sucrase and SI mRNA suggests that upregulation of this enzyme may be achieved by post-translational factor(s). We conclude that genetic mechanisms responsible for diet-induced flexibility of digestive enzymes in birds may differ from that observed in mammals.

Kinetics of human sperm acrosomal exocytosis.

The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.

Undernutrition affects embryo quality of superovulated ewes.

To determine the effect of undernutrition on embryo production and quality in superovulated sheep, 45 ewes were allocated into two groups to be fed diets that provided 1.5 (control, C; n = 20) or 0.5 (low nutrition, L; n = 25) times daily requirements for maintenance, from oestrous synchronization with intravaginal sponges to embryo collection. Embryos were collected 7 days after the onset of oestrus (day 0). Low nutrition resulted in lower live weight and body condition at embryo collection (P < 0.05). Diet (P < 0.01) and day of sampling (P < 0.001) significantly affected plasma non-esterified fatty acid (NEFA) and insulin concentrations. Plasma leptin concentrations decreased on day 7 only in L ewes. A significant effect of dietary treatment (P < 0.05) and day (P < 0.0001) was observed on plasma insulin-like growth factor (IGF)-I concentrations. The number of recovered oocytes and embryos did not differ between the groups (L: 15.4 ± 0.4; C: 12.4 ± 0.4). Recovery rate was lower (P < 0.05) in the L (60%) than in the C group (73%). The total number of embryos and number of viable-transferable embryos (5.0 ± 0.3 and 3.4 ± 0.3 embryos, respectively) of the L group were lower (P < 0.1) when compared with controls (8.4 ± 0.4 and 6.2 ± 0.4 embryos, respectively). Undernutrition during the period of superovulation and early embryonic development reduced total and viable number of embryos. These effects might be mediated by disruption of endocrine homeostasis, oviduct environment and/or oocyte quality.

Periconceptional undernutrition modifies endocrine profiles and hepatic gene expression in sheep.

This study investigated whether a 22-day period of undernutrition (half maintenance) could affect maternal endocrine responses and liver gene expression during early pregnancy (day 7). Thirty-five ewes were fed 1.5 (n = 15) or 0.5 (n = 20) their maintenance requirements and slaughtered on day 7 of the oestrus cycle or pregnancy (oestrus = day 0). Insulin, IGF, leptin and non-esterified fatty acids (NEFA) were determined on days -14, 0 and 7. Transcripts of the IGF family and adipokines receptors were determined in the liver by real-time RT-PCR. Underfed animals presented lower body weight and body condition, greater plasma concentration of NEFA, and lower plasma concentrations of leptin, insulin and IGF1 compared to adequately fed animals. Underfed ewes presented greater hepatic expression of IGFBP2 than well-fed ewes, but tended to have lesser expression of IGFBP5. While no effect of undernutrition on IGFBP4 and ADIPOR2 mRNA expressions was observed, they were increased by pregnancy in underfed animals. This study shows that undernutrition modifies endocrine profiles and hepatic gene expression of IGFBP2 and 5. The pregnancy status increased hepatic gene expression of IGFBP4 and ADIPOR2 mRNA in undernourished ewes.

Periconceptional undernutrition increases quantity and quality of oocyte population, but not cognitive or emotional response of 60-day-old lambs.

Maternal periconceptional undernutrition is associated with altered development and increased risks of adverse outcomes in the offspring. The aim of this work was to determine the effect of periconceptional undernutrition on behavioural and reproductive aspects of the offspring. Fifty ewes were synchronized in oestrus (day 0) and allocated to two groups (n = 25) to be fed diets that provided 1.5 (C) or 0.5 (L) times the requirements for maintenance until day 15. Ewes were mated and fed the control diet from day 16 until lambing. Two months after lambing, 26 lambs were exposed to tests to determine their cognitive/emotional responses. Six ewe lambs were euthanized and in vitro oocyte maturation and fertilization procedures performed. The experimental diets produced no changes of mean live weight (LW) of C ewes, L ewes presenting a reduction in their initial LW with significant differences at day 15, in comparison with C ewes (p < 0.05). L ewes experienced a significant reduction in their body condition (BC) in comparison with C ewes (p < 0.05). Fourteen days after the onset of the experimental diets, mean LW and BC of L ewes was significantly lower than those of C ewes (p < 0.05). Undernourished ewes presented a trend to a reduction of prolificacy and fecundity (p < 0.10) in comparison with C ewes. Emotional and cognitive test revealed a similar response between groups. Ewe lambs from the undernourished ewes presented a population of oocytes 1.7 times higher than ovaries from control ewe lambs (66.0 ± 0.73 vs. 113.7 ± 15.6 oocytes; p < 0.05) and had more oocytes in the 'good' (p < 0.05) and 'healthy' (p < 0.05) categories. In conclusion, a low plane of nutrition around conception significantly increases quantity and quality of the oocyte population of 60-day-old female descendants. Modifications of the cognitive and emotional responses of the progeny have not been evidenced.

Homogeneous colleters in Myrteae (Myrtaceae).

Colleters are secretory structures characteristic of the apices of more than 60 botanical families. In the Myrtaceae, three types of colleters were previously described: petaloid, conical, and euriform. In Argentina, most species of the Myrtaceae family grow in subtropical regions and a few in the temperate-cold zones of Patagonia. We evaluated the vegetative buds of five species of the subfamily Myrtoideae, tribe Myrtea: Amomyrtus luma, Luma apiculata, and Myrceugenia exsucca, native to the temperate rainforests of Patagonia and Myrcianthes pungens and Eugenia moraviana from the riparian forest of northwestern Corrientes, in order to analyze the presence and morphological types and main secretion products of colleters. Optical and scanning electron microscopy was used to identify the presence of colleters in vegetative organs. Histochemical tests were performed to identify the main secretion products in these structures. The colleters are on the inner side of the leaf primordia and cataphylls and on the edge of the petiole, where they replace the stipules. They are classified as homogeneous because they consist of epidermis and internal parenchyma, both formed by cells with similar characteristics. They lack vascularization and originate from the protodermis. The colleters are of the conical type in L. apiculata, M. pungens, and E. moraviana and of the euriform type in A. luma and M. exsucca, the latter being identified by its dorsiventrally flattened shape. Histochemical tests showed the presence of lipids, mucilage, phenolic compounds, and proteins. This is the first time that colleters have been described in the analyzed species; the taxonomical and phylogenetic importance of this structures is discussed in relation to the Myrtaceae family.

Association between ancient bone preservation and dna yield: a multidisciplinary approach.

Ancient molecular typing depends on DNA survival in archaeological bones. Finding valuable tools to predict DNA presence in ancient samples, which can be measured prior to undertaking a genetic study, has become an important issue as a consequence of the peculiarities of archaeological samples. Since the survival of DNA is explained by complex interrelations of multiple variables, the aim of the present study was to analyze morphological, structural, chemical, and biological aspects of a set of medieval human bones, to provide an accurate reflection of the state of preservation of the bony components and to relate it with DNA presence. Archaeological bones that yielded amplifiable DNA presented high collagen content (generally more than 12%), low racemization values of aspartic acid (lesser than 0.08), leucine and glutamic acid, low infrared splitting factor, small size of crystallite, and more compact appearance of bone in the scanning electron micrographs. Whether these patterns are characteristic of ancient bones or specific of each burial site or specimen requires further investigation.

Metabolic memory determines oviductal gene expression of underfed ewes during early gestation.

Our aim was to investigate the oviduct environment by studying oviduct gene expression after undernutrition in day-5 pregnant ewes with different initial (i) BCS, and its association with the number of embryos recovered. Thirty-six ewes were divided into 2 groups with different iBCS: iBCS ≥2.75 (n = 19; high, H) and iBCS ≤2.25 (n = 17; low, L), and were randomly assigned to two nutritional treatments for 20 days: 1.5 (control, C) or 0.5 (underfed, U) times the daily maintenance requirements. Thus, the final four groups were: high-iBCS control (HC, n = 9), high-iBCS underfed (HU, n = 10), low-iBCS control (LC, n = 9) and low-iBCS underfed (LU, n = 8). Samples of oviduct were collected and the expression of target genes was quantified using real-time PCR. While high-iBCS control ewes presented more ADIPOR1 mRNA than the high-iBCS underfed group (P < 0.05) and low-iBCS control ewes (P = 0.01), high-iBCS underfed group presented higher ADIPOR2 gene expression than low-iBCS underfed ewes (P < 0.01) evidencing a differential oviductal gene expression for these receptors. In high-iBCS ewes, control animals presented higher IGFBP2 gene expression than underfed ewes (P < 0.05), associated these results with a poor oviductal environment. High-iBCS underfed ewes presented higher IGFBP4 gene expression than high-iBCS control ewes (P < 0.05). Stepwise regression models, using various combinations of data on metabolic and reproductive hormones, and oviduct gene expression as independent variables, identified a set of variables that accounted for 75% of the variation in the number of embryos recovered. In conclusion, the oviductal gene expression depends on body reserves and nutritional treatment, and the effect is gene-specific.

[Has sexuality changed in pregnancy? Baby boom generation versus millennial generation]. / ¿Ha variado la sexualidad en el embarazo? Generación baby boom versus generación millennial.

Sexuality is a complex and multidimensional phenomenon that constitutes a fundamental component in human relationships. Pregnancy is a crucial period in women's life and the physiological changes that happen in this period affect their sexuality. OBJECTIVE: Knowing how pregnancy impacts on sexual behaviors in millenial generation compared to baby boom generation. MATERIAL AND METHODS: Descriptive and cross-sectional study, by means of a self-completed, population-based survey, to a sample of pregnant women in the third trimester of gestation who attended Primary Care. A descriptive study of the frequency distribution of all the variables was carried out. RESULTS: In baby boom generation and millennial generation, it is observed that during pregnancy couple's attraction decreases slightly. According to variables desire and frequency of intercourse, results obtained show that as the pregnancy progresses there is a marked decrease in desire and intercourse frequency. Women state that they do not have enough information about sexuality in their current state, despite years having passed. CONCLUSIONS: During last 35 years, sexual behaviors have not changed in pregnant women. In both generations, changes in desire and intercourse domains were particularly significant, being in third trimester of pregnancy when frequency of intercourse decline. Pregnant women continue to hold erroneous beliefs about sexuality and request more sexual education.

Short-term undernutrition affects final development of ovulatory follicles in sheep synchronized for ovulation.

The objective of this study was to determine, in sheep, the effect of a short-term undernutrition on growth dynamics and competence of pre-ovulatory follicles. Synchronization of sexual cycles and induction of ovulation were performed, with progestagens and gonadotrophins, in 14 adult female sheep. Morphological characteristics and developmental competence of ovarian follicles to achieve ovulation were determined by imaging techniques (ultrasonography and laparoscopy) and blood sampling. All the animals ovulated and mean ovulation rates were similar between groups (2.0 ± 0.6 corpora lutea in control ewes and 2.2 ± 0.8 in undernourished sheep). However, nutritional restriction, even during a short period, was related to the presence of large follicles in static growing phase which, despite reaching ovulation, persisted static during the induced follicular phase and evidenced functional alterations as there was no inhibition of the development of subordinate follicles. Thus, this study suggests the existence of deleterious effects from short-term undernutrition on functionality of pre-ovulatory follicles, which can compromise fertility.

Undernutrition and exogenous melatonin can affect the in vitro developmental competence of ovine oocytes on a seasonal basis.

This study evaluated the effects of exogenous melatonin and level of nutrition on oocyte competence, in vitro fertilization (IVF), and early embryonic development in sheep during seasonal anoestrus (SA) and the reproductive season (RS). Adult Rasa Aragonesa ewes were assigned randomly to one of four treatment groups in two experiments based on a 2 x 2 x 2 factorial design. Individuals were treated (+MEL) or not treated (-MEL) with a subcutaneous implant of melatonin for 42 days and then were fed 1.5 (Control, C) or 0.5 (Low, L) times the daily maintenance requirements for 20 days. Ewes were synchronized and mated at oestrus (Day = 0). On Day 5, ovaries were collected and oocytes were used for IVF. Season had a significant (p < 0.01) effect on the number of oocytes recovered (RS: 19.6 +/- 1.0; SA: 14.5 +/- 1.0) and the number of healthy oocytes (RS: 13.9 +/- 0.7; SA: 9.0 +/- 0.7). In the RS, neither nutrition nor melatonin had a significant effect on the evaluated oocytes quality parameters although melatonin implants appeared to reduce the number of unhealthy oocytes in the undernourished group (p < 0.05). During SA, in undernourished ewes exogenous melatonin tended to increase the number of healthy (L+MEL: 9.4 +/- 1.0, L-MEL: 7.6 +/- 1.4; p < 0.1), and significantly improved both cleaved oocytes (L+MEL: 7.0 +/- 0.7, L-MEL: 4.1 +/- 0.9; p < 0.05) and blastocyst rate (L+MEL: 37.2, L-MEL: 21.9%; p < 0.05). In conclusion, oocyte competence in ewes was affected by season, and melatonin implants appeared to improve developmental competence in the seasonal anoestrous period, particularly in experimentally undernourished ewes.

Effect of undernutrition on the uterine environment during maternal recognition of pregnancy in sheep.

The effects of pregnancy and undernutrition on endometrial gene expression were investigated in ewes fed all or half their maintenance requirements and killed on Day 14 of pregnancy or of the oestrous cycle. The endometrial expression of progesterone, oestrogen, oxytocin and interferon receptors (PR, ERalpha, OXTR and IFNAR, respectively), cyclo-oxygenase (COX)-2, proliferating cell nuclear antigen (PCNA), insulin-like growth factors (IGF)-I and -II, and IGF-1 receptor (IGF-1R) was studied by immunohistochemistry or real-time reverse transcription-polymerase chain reaction. The luminal epithelium of cyclic control ewes was devoid of PR staining and had relatively high levels of ERalpha, OXTR, COX-2 and IFNAR2. The presence of a conceptus decreased the in vitro uterine secretion of prostaglandin (PG) F(2alpha) and the expression of IFNAR2 in most cell types, and increased the gene expression of IGF-I and IGF-II. Undernutrition tended to increase ERalpha protein and gene, but decreased in vitro uterine secretion of PGE(2) and the gene expression of IFNAR2 in cyclic ewes. There was no effect of undernutrition on pregnancy rates or the number of conceptuses recovered. Consistent with this, undernutrition of pregnant ewes did not have any effect on uterine gene expression. Moreover, in cases where changes were observed in cyclic ewes, these changes were negated when a conceptus was present.

Dietary restriction in sheep: Uterine functionality in ewes with different body reserves during early gestation.

The aim of this study was to characterize insulin, leptin and IGF-1 profiles after undernutrition in pregnant ewes with different initial body condition (iBCS) and to investigate embryo quality, uterine gene expression and presence and location of proteins during early gestation (day 5). Thirty-six Rasa Aragonesa ewes were divided into 2 groups with different BCS: BCS> 2.75 (high, H, n = 19) and BCS <2.25 (low, L, n = 17) and they were randomly assigned to two nutritional treatments: 1.5 maintenance (M) (control, C) or 0.5 (M) (undernourishment, U) times the daily maintenance requirements establishing four groups: high-iBCS control (HC, n = 9), high-iBCS undernourished (HU, n = 10), low-iBCS control (LC, n = 9) and low-iBCS undernourished (LU, n = 8). High-iBCS ewes presented higher concentration of IGF-1, reflecting a better metabolic status in these animals. There was a greater proportion of high-iBCS ewes presenting more than one CL (P < 0.05), and associated greater P4 plasma concentration, number of recovered embryo and a tendency for higher embryo viability rate (P = 0.13). In uterus, undernourished ewes tended to present lower P4 (P = 0.09) and higher E2 concentration (P = 0.10). Inmunostaining of uterine progesterone and estrogen receptors (PR and ERα) was not affected by iBCS and nutritional treatment. Ewes with low-iBCS tended to have more INSR mRNA, and undernourished ewes tended to have more IGFBP2 mRNA expression (P < 0.08). An interesting finding was that the uterine response to undernutrition was dependent on iBCS: a higher expression of GHR (P < 0.05) and a tendency in IGFBP5 (P = 0.09) mRNA was found in undernourished than control ewes but only in the high-iBCS group. In summary, the present study demonstrates that the endocrine response and the uterine gene expression to undernutrition depend on the initial body energy reserves (iBCS) and appears to be associated with a differential embryo quality.

Undernutrition reduces the oviductal mRNA expression of progesterone and oestrogen receptors in sheep.

The effect of undernutrition on the oviductal mRNA expression of oestrogen and progesterone receptors (ERalpha and PR) determined by a solution hybridisation assay in sheep was investigated. Adult ewes were fed either 1.5 (C) or 0.5 (L) times their maintenance requirements and were slaughtered on day 5 or 14 of a synchronised oestrous cycle (day 0=oestrus). In the oviduct ipsilateral to the corpus luteum, Group L presented lesser concentrations of ERalpha mRNA than Group C on day 5 (P<0.05), and lesser PR mRNA concentrations on both days (P<0.05). No effect of undernutrition was observed in the contralateral oviduct, and there was no difference in transcripts concentrations between days 5 and 14. The lesser sensitivity of the oviduct to ovarian steroids found in undernourished ewes could compromise the embryo environment and partly explain the retarded development reported in embryos collected from nutritionally restricted ewes.

¿Ha variado la sexualidad en el embarazo? Generación baby boom versus generación millennial / Has sexuality changed in pregnancy? Baby boom generation versus millennial generation

La sexualidad es un fenómeno complejo y multidimensional que constituye un componente fundamental en las relaciones humanas. El embarazo es un periodo crucial en la vida de las mujeres y los cambios fisiológicos que ocurren durante este periodo inciden en su sexualidad. Objetivo: Conocer qué impacto produce la gestación en las conductas sexuales en la generación millennial comparado con la generación baby boom. Material y métodos: Estudio descriptivo y transversal, mediante encuesta autocumplimentada, de base poblacional, a una muestra de mujeres embarazadas en el tercer trimestre de gestación que acudían a una consulta del equipo de atención primaria. Se realizó un estudio descriptivo de distribución de frecuencias de todas las variables. Resultados: Tanto en la generación baby boom como en la generación millennial se observa que durante el embarazo la atracción por la pareja disminuye ligeramente. En las variables deseo y frecuencia de coito los resultados obtenidos muestran que a medida que progresa el embarazo hay una disminución marcada del deseo y la frecuencia coital. Las mujeres manifiestan que no tienen suficiente información sobre la sexualidad en su estado actual, a pesar de los años transcurridos. Conclusión: Las conductas sexuales en las mujeres embarazadas no han cambiado en los últimos 35 años. Los cambios observados en ambas generaciones, en los dominios deseo y coito, fueron particularmente notables, siendo en el tercer trimestre de embarazo cuando más decae la frecuentación del coito. Las gestantes siguen manteniendo creencias erróneas acerca de la sexualidad y solicitan más educación sexual (AU)

Sexuality is a complex and multidimensional phenomenon that constitutes a fundamental component in human relationships. Pregnancy is a crucial period in women's life and the physiological changes that happen in this period affect their sexuality. Objective: Knowing how pregnancy impacts on sexual behaviors in millenial generation compared to baby boom generation. Material and methods: Descriptive and cross-sectional study, by means of a self-completed, population-based survey, to a sample of pregnant women in the third trimester of gestation who attended Primary Care. A descriptive study of the frequency distribution of all the variables was carried out. Results: In baby boom generation and millennial generation, it is observed that during pregnancy couple's attraction decreases slightly. According to variables desire and frequency of intercourse, results obtained show that as the pregnancy progresses there is a marked decrease in desire and intercourse frequency. Women state that they do not have enough information about sexuality in their current state, despite years having passed. Conclusions: During last 35 years, sexual behaviors have not changed in pregnant women. In both generations, changes in desire and intercourse domains were particularly significant, being in third trimester of pregnancy when frequency of intercourse decline. Pregnant women continue to hold erroneous beliefs about sexuality and request more sexual education (AU)

Cigarette smoking increases the risk of root canal treatment.

Few studies have investigated smoking as a risk factor for root canal treatment. We studied the effect of smoking on the incidence of root canal treatment, controlling for recognized risk factors, in 811 dentate male participants in the VA Dental Longitudinal Study. Participants were not VA patients. Follow-up ranged from 2 to 28 years. Root canal treatment was verified on radiographs and evaluated with proportional hazards regression models. Compared with never-smokers, current cigarette smokers were 1.7 times as likely to have root canal treatment (p < 0.001), but cigar and/or pipe use was not significantly associated with root canal treatment. The risk among cigarette smokers increased with more years of exposure and decreased with length of abstinence. These findings suggest that there is a dose-response relationship between cigarette smoking and the risk of root canal treatment.

Effect of undernutrition on uterine progesterone and oestrogen receptors and on endocrine profiles during the ovine oestrous cycle.

In the present study, it was investigated whether undernutrition affected the binding capacity, immunoreactivity and mRNA expression for uterine oestrogen and progesterone receptors (ER and PR, respectively) in sheep, as well as whether the responses were associated with changes in plasma concentrations of progesterone (P4), oestradiol (E2), glucose, fatty acids, insulin, leptin and insulin-like growth factor (IGF)-I during the oestrous cycle. Twenty ewes were fed either 1.5 (C) or 0.5 (L) times their maintenance requirements and were killed on Day 5 or 14 of the cycle (Day 0 = oestrus). Compared with Group C, Group L had higher concentrations of non-esterified fatty acids and lower concentrations of insulin, leptin and IGF-I. Group L also had higher plasma concentrations of P4 during the final days of the luteal phase. At oestrus in both treatment groups, there were peaks in the concentrations of glucose, insulin and IGF-I. For ER and PR, transcript expression, binding capacity and immunoreactivity were higher on Day 5 than on Day 14 of the cycle. The binding capacities for ER and PR were lower in Group L than in Group C on Day 5. Group C showed more immunoreactive staining for ER than did Group L in two of five cell types, whereas no effect of treatment was observed for PR immunoreactivity. There was more PR mRNA in the uterine horn contralateral to the corpus luteum in Group C than in Group L ewes. We conclude that undernutrition impairs steroid receptor expression and binding capacity. This may alter the uterine environment and help explain the reductions in embryo survival.