Site-specific changes in brain extra-SCN oscillators during early pregnancy in the rat

The influence of circadian timekeeping systems on behavior and physiology can change substantially as female mammals undergo the transition from a nonpregnant to a pregnant state. Here, we examined the possibility that site-specific changes in extra-SCN oscillators and in local rhythms might coincide with the emergence of new patterns of temporal organization among various behavioral and physiological rhythms. Specifically, we compared daily patterns of immunoreactive FOS and PER2 in 3 brain regions of pregnant and diestrous rats. We found that, in the oval nucleus of the bed nucleus of the stria terminalis (BnST-ov), the peak of the PER2 rhythm occurred approximately 12 hours out of phase in pregnant and diestrous females. In contrast, the phase of the rhythm in FOS was the same, but pregnant rats expressed more FOS in the BnST-ov than diestrous ones. In the central amygdala (CEA) of diestrous females, PER2 expression was arrhythmic, but Fos expression was elevated at night. No rhythms were seen in this region of pregnant females, nor were any rhythms seen in the basolateral amygdala of either group. Overall, the patterns in the BnST-ov and the CEA were consistent with the hypothesis that differential changes in daily rhythms within some extra-SCN brain regions might mediate the changes in the temporal organization of several behavioral and endocrine functions that occur during the transition from a nonpregnant to a pregnant state.     

Enzymic activity in rat uterus during early pregnancy.

Total protein, RNA and DNA content and the activity of acid and alkaline phosphatases, 5'-nucleotidase and isocitrate dehydrogenase were studied in rat uterus during the first 8 days of pregnancy. Isocitrate dehydrogenase activity showed marked fluctuations from day to day. Nucleotidase and acid phosphatase activities showed a significant increase on day 8. The most marked change in activity was that of alkaline phosphatase which showed a 10-fold increase between days 6 and 8, due largely to an increase in the activity of this enzyme in the decidual nodule. The rise in alkaline phosphatase activity did not occur in rats ovariectomized on days 1, 2 or 4 of pregnancy and was markedly decreased in those ovariectomized on day 6. [3H]-uridine incorporation into RNA showed a significant increase between days 2 and 6 whereas [3H]-thymidine incorporation into DNA showed a significant increase on day 6.     

Genomic organization and sequence of the rat major histocompatibility complex class Ia gene RT1.A u

The nucleotide sequence data reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession number X82669     

Endometrial cell death during early pregnancy in the rat

In a study of early pregnancy in the rat, a high proportion of morphologically apoptotic, TUNEL and P2X₇ positive cells were found to be present in the luminal epithelium and stroma prior to implantation. At the time of implantation on Day 6, apoptosis as measured by these indicators was reduced up to 4-fold in the non-implantation uterine epithelium but was markedly increased adjacent to the implanting blastocyst. It is proposed that apoptotic cell death is an important regulatory factor involved in uterine remodelling prior to and during implantation.     

Uterine protein synthesis during the early stages of pregnancy in the rat.

The synthesis of uterine-soluble proteins during early pregnancy in the rat has been examined by means of dual-isotope labelling techniques and subsequent electrophoretic analysis. A protein of similar electrophoretic mobility to the uterine oestrogen-induced protein was observed, and synthesis of this 'presumptive induced protein' was maximal on Day 4 and Day 6 of pregnancy but low on day 5. Pregnancy associated protein synthesis was observed in many regions on polyacrylamide gels, including the beta-lipoprotein, alpha2-macroglobulin, post-transferrin and albumin regions. Synthesis of the post-transferrin species rapidly increased from Day 4 to reach a maximum on Day 6 in the implantation tissue. The temporal pattern of synthesis of post-transferrin protein and and of 'presumptive induced region' suggests involvement in the processes of cell proliferation and decidualization.     

Polymorphism and mapping of the class II genes in the rat: RT1.B,RT1.D,and RT1.H,a new DP-like region

The major histocompatibility complex of the rat (RTI) encodes the class II molecules involved with antigen presentation and cell to cell communication. The organization of these class II genes has been studied by Southern blot hybridization using genomic DNA from inbred and recombinant rat strains digested with various restriction endonuclease and hybridized under stringent conditions with probes for mouse class II and human class II genes. Analysis of the restriction fragment length polymorphisms has mapped the class II genes relative to each other. We have confirmed the order of the - and -chain genes in the RT1.B region, mapped the RT1.D region relative to RT1.B and showed that it has - and -chain loci, and identified a new HLA-DP-like locus, RT1.H, to the RT1.A side of RT1. B. The RT1. H and RT1.H genes map to the region around the recombination point in R22, and there appears to be a hot spot of recombination in RT1.H. The H and D genes have high levels of polymorphism; B , B ,and H have intermediate levels of polymorphism, and D has a low level of polymorphism.     

Oestrogen pattern during early pregnancy in the mare.

Plasma total (conjugated + unconjugated) oestrogens were measured from Day 0 to 100 of pregnancy and compared with the levels found during the oestrous cycle. From Day 0 to 35 of gestation, the concentrations were similar to those during dioestrus. An increase in total oestrogens between Days 35 and 40 was followed by a plateau of 3 ng/ml between Days 40 and 60 which was slightly higher than preovulatory concentrations. This first increase in total oestrogen level was produced by the ovaries since values were suppressed after ovariectomy; stimulation may be due indirectly to PMSG causing follicular growth. After Day 60, a second increase was detected and considered to be of feto-placental origin as the levels at this time were not suppressed after ovariectomy. By Day 85, oestrogen concentrations exceeded thos detected in non-pregnant mares so that a direct measurement of total oestrogens in plasma by a simplified radioimmunoassay after Day 85 of gestation offers a reliable method of pregnancy diagnosis.     

Enzyme changes in rat small intestine during pregnancy and lactation

Synopsis Small fluctuations in the activity of a number of important enzymes have been found during the intestinal hyperplasia and hypertrophy of pregnancy and lactation. The pattern of change differs between the enzymes studied, and for individual enzymes often varies between the jejunum and ileum. These results suggest that there must be a complex response to the signals that trigger hyperplasia in the mucosal epithelium.     

Adipose tissue metabolism during early pregnancy in the rat: temporal relationships of changes in the metabolic activity, number of insulin receptors, and serum hormone concentrations

The temporal relationships between changes in rates of fatty acid and acylglycerol glycerol synthesis; the activity of lipoprotein lipase of parametrial adipocytes and their capacity to bind insulin; and the serum concentrations of insulin, progesterone, prolactin, and total lactogenic activity have been examined in rats during the first 15 days of pregnancy. The rate of fatty acid and acylglycerol synthesis showed a transient increase at Days 9 and 12 of pregnancy, whereas there was no change in the activity of lipoprotein lipase activity except for a fall between Days 12 and 15 of pregnancy. The capacity of adipocytes to bind insulin was increased by Day 6 of pregnancy and remained elevated until at least Day 15; no changes in the affinity for insulin were observed. Serum progesterone, insulin, and total lactogenic activity were elevated by Days 3, 9, and 12 of pregnancy, respectively. The results show that progesterone but not placental lactogen could be responsible for the rise in the insulin-binding capacity of rat adipocytes during pregnancy, whereas the fall in lipogenic capacity at about Day 12 of pregnancy coincides with the rise in serum placental lactogen.