Single Injection Of Progesterone Research Articles

Respiratory regulation by steroids in newborn rats: a sex-specific balance between allopregnanolone and progesterone receptors.

What is the central question of this study? What are the contributions of allopregnanolone, the neuroactive metabolite of progesterone, and nuclear (nPR) and membrane (mPR) progesterone receptors to the respiratory effect of progesterone in newborn rats? What is the main finding and its importance? Acute progesterone injection increases the apnoea frequency, whereas finasteride (which blocks the conversion of progesterone to allopregnanolone) reduces apnoea frequency. An nPR agonist decreases apnoea frequency in males and an mPR agonist decreases apnoea frequency in males and females. Chronic injection of progesterone decreases the frequency of apnoea more efficiently in males than in females. We tested the hypothesis that the effects of progesterone on apnoea frequency in newborn rats are the result of a balance between its neuroactive metabolite, allopregnanolone (GABAA receptor modulator), and progesterone receptors. We used male and female rats between 10 and 12days of age and recorded respiratory and metabolic parameters (whole-body plethysmography), and assessed the frequency and duration of apnoeas in normoxia. We tested the effects of a single injection of progesterone (4mgkg-1 , i.p.), finasteride (10mgkg-1 , i.p.; a 5α-reductase antagonist, which blocks the conversion of progesterone to allopregnanolone), finasteride plus progesterone, or agonists of the nuclear or membrane progesterone receptors (R5020 or Org-od-02-0, 4mgkg-1 ). To test the hypothesis that chronic exposure to progesterone reduces the frequency of apnoeas, we used male and female rats treated daily with progesterone between postnatal days 3 and 12. The acute injection of progesterone reduced minute ventilation and metabolic rate and increased the frequency of apnoeas. Finasteride decreased the frequency of apnoeas, and finasteride plus progesterone did not increase apnoea frequency but decreased minute ventilation in female rats. Although R5020 decreased apnoea frequency only in males, Org-od-02-0 decreased apnoea frequency in males and females and decreased respiratory frequency in females. Chronic progesterone treatment reduced apnoea frequency more efficiently in males than in females, but in females (not in males) an acute injection of caffeine (the gold standard for the treatment of apnoea in preterm neonates) further reduced apnoea frequency. Apnoea frequency in newborn rats is, in part, determined by a sex-specific balance between allopregnanolone, GABAA receptors and progesterone receptors.

Wnt Genes in the Mouse Uterus: Potential Regulation of Implantation1

Wnt genes are involved in critical developmental and growth processes. The present study comprehensively analyzed temporal and spatial alterations in Wnt and Fzd gene expression in the mouse uterus during peri-implantation of pregnancy. Expression of Wnt4, Wnt5a, Wnt7a, Wnt7b, Wnt11, Wnt16, Fzd2, Fzd4, and Fzd6 was detected in the uterus during implantation. Wnt4 mRNA was most abundant in the decidua, whereas Wnt5a mRNA was restricted to the mesometrial decidua during decidualization. Wnt7a, Wnt7b, and Wnt11 mRNAs were abundantly detected in the endometrial epithelia. The expression of Wnt7b was robust in the luminal epithelium (LE) at the implantation site on Gestational Day 5, whereas Wnt11 mRNA disappeared in the LE adjacent to the embryo in the antimesometrial implantation chamber but remained abundant in the LE. Wnt16 mRNA was localized to the stroma surrounding the LE on Day 4 and remained in the stroma adjacent to the LE but not in areas undergoing the decidual reaction. Fzd2 mRNA was detected in the decidua, Fzd4 mRNA was in the vessels and stroma surrounding the embryo, and Fzd6 mRNA was observed in the endometrial epithelia, stroma, and some blood vessels during implantation. Ovarian steroid hormone treatment was found to regulate Wnt genes and Fzd receptors in ovariectomized mice. Especially, single injections of progesterone stimulated Wnt11 mRNA, and estrogen stimulated Wnt4 and Wnt7b. The temporal and spatial alterations in Wnt genes likely play a critical role during implantation and decidualization in mice.

Progesterone Plus PMSG Priming in Seasonally Anovulatory Lactating Sarda Ewes Exposed to the Ram Effect

The aim of this trial was to evaluate the effectiveness (fertility and lambing) of priming with a single injection of progesterone plus PMSG in anovulatory lactating Sarda ewes subjected to the ram effect (RE) in spring. Thirty ewes (P4 group) were i.m. injected with 30 mg progesterone and 500 IU PMSG 36 h before ram introduction (d 0). This treatment was compared to a 12-day treatment with fluorogestone acetate intravaginal sponges that was followed by injections of 350 IU PMSG upon sponge withdrawal (FGA group, n=30). All ewes responded to RE, showing plasma progestrone concentrations >1 ng/mL between d 6 and 12 (FGA) or 6 and 9 (P4). Eighty-nine percent of the P4 ewes conceived at first ovulation, and 11% conceived following a short estrus cycle. Lambings occurred on d 150.4 +/- 3.9, and the lambing rate was 100%. The fertility of the FGA ewes was 83% for the induced ovulation and was 7% for the second ovulation after a normal cycle. The FGA ewes lambed on d 149.8 +/- 4.4, and the lambing rate was 83%. Two abortions were recorded for the FGA ewes, which had higher prolificacy than the P4 group (2.2 +/- 0.8 vs. 1.8 +/- 0.4, respectively; P<0.05). Both fertility and the lambing rate were high in both groups, with a high degree of estrus synchronization, and there were no significant differences between the groups. We concluded that priming of lactating Sarda ewes in spring with P4+PMSG before RE is an effective and competitive method (cheaper and more practical than FGA+PMSG) of inducing fertile ovulations in these ewes.

Oestrous behaviour and development of preovulatory follicles in goats induced to ovulate using the male effect with and without progesterone priming

The objective of the current study was to examine follicular dynamics in goats induced to ovulate by using the male effect with or without progesterone pretreatment. Ten Murcian-Granadina goats were treated with a single dose of 25 mg of progesterone in olive oil on the day of male effect induction (Day 0), whereas ten does remained untreated. Changes in the ovarian follicular population and onset of oestrous behaviour were checked daily from Day 0 to the day on which ovulation was detected by ultrasonography. All of the treated goats and only 20% of control goats (P < 0.001) showed oestrous behaviour between 72 and 96 h after the introduction of bucks. Differences in follicle growth were found between the groups. The control goats exhibiting oestrous behaviour during the first 4 days of ovarian screening and all of the goats treated with progesterone had their preovulatory follicles in growing phase. However, the largest follicles in control does not showing oestrus in these first 4 days were in regressing phase, being necessary for the emergence of new preovulatory follicles from a new follicular wave between Days 6 and 7, for exhibition of oestrous behaviour and subsequent ovulation. In conclusion, the appearance of short luteal phases and delayed ovulation in goats treated with the male effect during seasonal anoestrous depends on the stage of follicle development at the time of buck introduction. A single injection of progesterone stimulates the emergence of a new follicular wave, able to grow and give adequate ovulation after induction of the male effect.

Microarray profiling of gene expression patterns in adult male rat brain following acute progesterone treatment

Progesterone can influence various behaviors in adult male rats, however, little is known about which particular genes are regulated by progesterone in the male rat brain. Using focused microarray technology, we where able to define a subset of genes that are responsive to progesterone. Nylon membrane-based cDNA microarrays were used to profile gene expression patterns in the preoptic area/mediobasal hypothalamus (POA/MBH) of male rat brain 7 h following a single injection of progesterone. RNA was isolated from the brains of 6 male rats injected with progesterone and 6 male rats injected with sesame oil. Next, we hybridized the RNA from each animal to individual cDNA microarrays that contained more than 100 target genes, all of which are involved in cAMP and or calcium signaling pathways. Direct side-by-side comparison of all 12 arrays revealed differences in the expression patterns of 12 different genes. We confirmed the data gathered from the arrays on 4 different genes using Real-Time PCR. These data begin to outline the important role played by progesterone in mediating changes in gene expression within the male brain.

Effect of a single injection of progesterone on ovarian follicular cysts in lactating dairy cows

The objective of this experiment was to evaluate the effect of a single injection of progesterone on the lifespan of ovarian follicular cysts and to examine the fate of follicles that mature following treatment. Lactating Holstein and Jersey cows with ovarian follicular cysts were identified by rectal palpation. The ovaries of cystic cows were then examined by transrectal ultrasonography three times weekly to monitor formation of new follicular cysts. Cows with newly formed follicular cysts were treated either with a single injection of progesterone (200 mg, IM, n = 11) or corn oil vehicle ( n = 7). Venous blood samples were collected daily for quantification of progesterone. Blood sampling and ultrasonography continued until ovulation or a new follicular cyst formed. Treatment reduced the lifespan of the cyst by 12 days, from 29.8 ± 2.3 days in control cows to 17.2 ± 1.8 days in progesterone-treated cows ( P = 0.01). Progesterone treatment also tended to alter the frequency of subsequent follicular events. Ovulation occurred in 4/11 cows that were treated with progesterone whereas none of the vehicle treated cows ovulated ( P = 0.07). In conclusion, a single injection of 200 mg of progesterone, administered early in the life of an ovarian follicular cyst, shortened its lifespan and in some cases was followed by ovulation of a new follicle.

Acute progesterone can recruit sex-specific neurochemical mechanisms mediating swim stress-induced and κ-opioid analgesia in mice

There is a qualitative sex difference in the neurochemical mediation of stress-induced and κ-opioid analgesia; these phenomena are dependent on N-methyl- d-aspartic acid (NMDA) receptors in males but not females. Progesterone modulation of this sex difference was examined in mice. Analgesia against thermal nociception was produced by forced cold water swim or by systemic administration of the κ-opioid agonist, U50,488. As seen previously, the NMDA receptor antagonist MK-801 blocked both forms of analgesia in male but not female mice. Also as in previous studies, this sex difference was found to be dependent on ovarian hormones such that ovariectomy induced female mice to “switch” to the male-like, NMDAergic system. We now demonstrate that a single injection of progesterone (50 μg), systemically administered 30 min before analgesia assessment, is sufficient to restore female-specific mediation of analgesia (i.e., insensitivity to MK-801 blockade) in ovariectomized female mice. The rapidity of this neurochemical “switching” action of progesterone suggests mediation via cell surface receptors or the action of neuroactive steroid metabolites of progesterone.

Progesterone Protects against Necrotic Damage and Behavioral Abnormalities Caused by Traumatic Brain Injury

A single injection of progesterone can attenuate cerebral edema when administered during the first 24 h after traumatic brain injury (TBI) in rats but this regimen may not always produce functional benefits. In this experiment, we sought to find the duration of progesterone administration needed to facilitate both behavioral and morphological recovery. Male rats received bilateral contusions of the medial prefrontal cortex and were given progesterone (4 mg/kg) or vehicle for 3 or 5 days postoperatively. Both the 3- and the 5-day progesterone regimens reduced the size of injury- induced necrosis and cell loss, with the 5-day schedule being most effective. With regard to behavioral outcome, only 5 days of progesterone injections resulted in improved spatial learning performance and reduced sensory neglect. These results show that 5 days of postinjury progesterone treatment are needed to reduce significantly the neuropathological and behavioral abnormalities found in a rodent model of TBI. These benefits of progesterone, in the absence of any known side effects, provide further support for clinical testing of this neurosteroid.

Ovarian follicular development following administration of progesterone or aspiration of ovarian follicles in holstein cows

The objective of this study was to compare the effects of administration of a single injection of progesterone (P 4) and follicle aspiration on Day 7 of the estrous cycle on the timing and synchrony of follicular wave emergence, time of ovulation, and concentrations of P 4, estradiol and FSH in Holstein cows. Twenty cows were assigned to 4 groups (n=5 cows per group) in a 2 by 2 factorial arrangement. Cows were treated on Day 7 (Day 0=estrus) of the estrous cycle with either sham follicular aspiration and an oil vehicle administered intramuscularly (control), aspiration of ovarian follicles (aspiration), 200 mg of P 4 im, or aspiration and 200 mg of P 4 im (aspiration + P 4). On Day 11, PGF 2α(25mg) was administered to all groups. Synchrony of ovulation was less variable in each of the treatment groups compared with the control group (P<0.05), whereas ovulation was delayed in cows in the P 4 group (P<0.05). Day of follicular wave emergence was delayed in the cows of the P 4 group compared with cows in the aspiration and aspiration + P 4 groups (P<0.01), whereas variability in wave emergence was less among both groups of aspirated cows compared with the cows in the control group (P<0.01). More follicles 4 to 7 mm in diameter were detected in the 2 aspiration groups compared with the cows in the control and P 4 group (P<0.05). No difference was detected among groups in the maximum concentration of FSH associated with follicular wave emergence. We conclude that both the administration of P 4 and the aspiration of follicles on Day 7 of the estrous cycle improves the synchrony of ovulation when luteolysis is induced on Day 11 and results in similar concentrations of FSH at the time of follicular wave emergence, but the timing of wave emergence and the number of follicles post-emergence differ.

Memory retention is modulated by acute estradiol and progesterone replacement.

Ovarian hormones alter spine density of hippocampal granule and pyramidal cells in young adult and aging female rats (P. Miranda, C. L. Williams, & G. Einstein, 1999; C. S. Woolley, 1998). The present study used a delayed matching-to-place version of the water maze to investigate a behavioral correlate of these hormone-induced changes in hippocampal connectivity in 3- and 8-month-old female rats. When primed with 10-microg injections of estradiol 72 and 48 hr before testing, the memory retention of ovariectomized rats was improved compared with retention after priming with oil. A single injection of progesterone maintained this enhancement if testing occurred within 8 hr of the progesterone injection but not if testing occurred more than 24 hr after the progesterone injection. These findings indicate that estradiol and progesterone alter memory retention and suggest that these changes may be the result of hormone-induced increases in hippocampal connectivity.

Limbic seizures alter reproductive function in the female rat.

Reproductive dysfunction and endocrine disorders are common among women with temporal lobe epilepsy. This study used the kindled rat model to test the hypothesis that limbic seizures directly contribute to reproductive dysfunction. Kindling electrodes were implanted in the basolateral amygdala in adult female rats. Females were kindled by either brief, daily, suprathreshold stimulations with a bipolar electrode or sham-kindled (controls). Electrographic and behavioral seizures were monitored. Estrous cycles also were monitored with daily vaginal smears. Seizures arrested ovarian cyclicity in all (n = 42) kindled animals, the rats exhibiting persistent vaginal cornification (PVC). In these animals PVC was associated with high serum estradiol, increased pituitary weight, and polyfollicular ovaries consisting of many cystic follicles, as well as follicles in various stages of growth and atresia. In 93% of females, this effect occurred after the development of stage 5 motor seizures, when focal seizures had secondarily generalized. In contrast, only five (21%) of 24 sham-kindled controls exhibited PVC. A single injection of progesterone (P4) temporarily restored cyclicity in five (18%) of 28 kindled females exhibiting PVC. In contrast, P4 administration restored cyclicity in all five sham-kindled controls that had spontaneously stopped cycling. P4 treatment to kindled females in PVC resulted in a different endocrine profile than that in non-P4-treated, kindled rats in PVC. P4-treated rats had high serum estradiol, testosterone, and prolactin levels; they showed an increase in pituitary weight; and their ovaries contained numerous corpora lutea and cystic follicles surrounded by markedly overdeveloped thecal cell layers. Seizures initiated in the amygdala result in impairment of the hypothalamic-pituitary axis, resulting in loss of ovarian cyclicity.

Levels of trkA and BDNF mRNA, but not NGF mRNA, fluctuate across the estrous cycle and increase in response to acute hormone replacement

Recent studies suggest that hormone replacement therapy can help to reduce the risk and severity of Alzheimer's-related dementia in postmenopausal women. We have hypothesized that these effects are due, in part, to the ability for estrogen and progesterone to enhance hippocampal function, as well as the functional status of cholinergic projections to the hippocampus and cortex, by influencing the expression of specific neurotrophins and neurotrophin receptors. In the present study, quantitative in situ hybridization techniques were used to determine whether the levels of trkA mRNA in the basal forebrain, and nerve growth factor (NGF) mRNA and brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus, are significantly affected by physiological changes in circulating gonadal steroids. Gonadally intact animals were sacrificed at different stages of the estrous cycle and ovariectomized animals were sacrificed at different times following the administration of either estrogen or estrogen plus progesterone. In gonadally intact animals, significant fluctuations in the levels of trkA mRNA in the medial septum (MS), and BDNF mRNA in regions CA1 and CA3/4 of the hippocampus, were detected across the estrous cycle. In animals that received hormone replacement, a significant increase (30.4%) in trkA mRNA was detected in the MS of animals sacrificed 24 h following estrogen administration. Levels of trkA mRNA in the MS declined to control levels over the next 48 h; however, a single injection of progesterone administered 48 h after estradiol appeared to prevent any further decline in trkA mRNA over the next 24 h. In addition, significant increases in BDNF mRNA were detected in the dentate granule cell layer (73.4%), region CA1 (28.1%), and region CA3/4 (76.9%) of animals sacrificed 53 h after receiving estrogen and 5 h after receiving progesterone. No significant changes in trkA mRNA were detected in the nucleus basalis magnocellularis, and no significant changes in NGF mRNA were detected in the hippocampus. These data demonstrate that levels of trkA mRNA in the MS, and BDNF mRNA in the hippocampus, are affected by physiological changes in the levels of circulating gonadal steroids and are elevated in response to acute hormone replacement. The relevance of these effects to the ability for estrogen replacement to enhance cholinergic activity and hippocampal function, and thereby reduce the risk and severity of Alzheimer's-related dementia in postmenopausal women, is discussed.

Differential regulation of gonadotropin-releasing hormone (GnRH) receptor expression in the posterior mediobasal hypothalamus by steroid hormones: implication of GnRH neuronal activity

The present study is designed to evaluate the relationship between gonadotropin-releasing hormone (GnRH) and GnRH receptor ( GnRHR) gene expression during the steroid-induced LH surge. One week after ovariectomy (OVX), a capsule containing 17β-estradiol (E) or vehicle (V) was implanted into OVX rats, and 2 days later a single injection of progesterone (P) or V was administered s.c. at 10:00 h. Poly(A)-rich RNA samples were isolated from the micropunches of the preoptic area (POA) and the posterior mediobasal hypothalamus (pMBH) from both sides of individual brain slices. Using competitive reverse transcription–polymerase chain reaction (RT-PCR) procedures, three parameters (POA GnRH, pMBH GnRHR and pituitary GnRHR mRNA levels) were simultaneously determined in each individual animal. POA GnRH mRNA and pituitary GnRHR mRNA levels were decreased by treatment with E, but increased by a combination of E and P. In contrast, pMBH GnRHR mRNA levels were clearly augmented by treatment with E, and decreased by the combination of E and P. Temporal changes in such parameters were determined in OVX+E+V- and OVX+E+P-treated rats. P augmented POA GnRH mRNA levels at the time of the LH surge (17:00 h) and the increased GnRH mRNA levels were remained until 22:00 h, while E alone failed to alter POA GnRH mRNA levels. In the pMBH micropunch samples, P substantially decreased E-induced increase in GnRHR mRNA levels at 17:00 h and further lowered those until 22:00 h. Antisense oligonucleotides of GnRHR mRNA administered into the lateral ventricle of OVX+E-treated rats blocked the E-induced increase in pMBH GnRHR mRNA levels. The antisense oligonucleotides also prevented the LH surge as well as the increase in pituitary GnRHR mRNA levels in the OVX+E+P-treated group. However, administration of this antisense oligonucleotides failed to alter POA GnRH mRNA levels. In conclusion, the present study demonstrated that there is an inverse relationship between POA GnRH mRNA levels and pMBH GnRHR mRNA levels in response to E and/or P, and that the blockade of the E-induced increase in pMBH GnRHR mRNA levels effectively nullified the P-induced LH surge. These results indicate that pMBH GnRHR gene expression is involved in synchronizing the GnRH neuronal activity, which is crucial for the generation of the LH surge.

Hormone-dependent changes in A and B forms of progesterone receptor.

The influence of different estrogen and/or progesterone treatments on concentrations of A and B forms of progesterone receptor (PR-A and PR-B) in the different cell types of chick oviduct was studied. A semiquantitative immunohistochemical assay for cellular PR concentrations was developed using a computer-assisted image analysis system. The staining intensity of nuclear PR in the basal layer of epithelial cells, glandular, smooth muscle and mesothelial cells was analysed separately using two monoclonal antibodies, PR6 and PR22. The measured concentrations of PR varied between different cell types and from cell to cell. A significant decrease in PR concentration, as noted by a decrease in staining intensity, was observed in all cell types studied 2 or 6 h after a single injection of progesterone with or without simultaneous estrogen administration. The decrease was also verified with immunoblotting and an immunoenzymometric assay (IEMA) for chicken PR. After down-regulation the concentration of PR recovered to the control level within 48 h after progesterone or estrogen administration. Estrogen administration alone was observed to cause changes in the concentration of PR-A only, having little or no effect on PR-B concentration depending on the cell type studied. These findings indicate that estrogen and progesterone cause cell-specific changes not only to the total concentration of PR but also to the cellular ratio of PR-A and PR-B.

Effect of estradiol and progesterone on cholesterol 7α-hydroxylase activity in rats subjected to different feeding conditions

The regulation of cholesterol 7α-hydroxylase activity by estradiol and progesterone was investigated in liver microsomes isolated from rats fed standard diet, either ad libitum or fasted for 24 h, and diet containing the bile acid sequesterant cholestyramine. Differentieffects were observd when the direct action of estradiol and progesterone on microsome preparations was examined. Cholesterol 7α-hydroxylase activity was inhibited by progesterone in a dose-dependent way to almost complete abolition; similar patterns of declines were found in the three feeding groups under study. In contrast, the addition of 5 μM estradiol induced small and selective 7α-hydroxylase increases in fasting and cholestyramine-fed animals, then activity declined to control values and consistent decreases were found from 20 μM. The administration of estradiol (50 μg) or progesterone (100 μg) for 21 days resulted in depressed cholesterol 7α-hydroxylase activity in rats with high bile acid synthesis basal rate due to cholestyramine feeding. In rats receiving a standard diet, either ad libitum or after 24 h fasting, the hormonal effects did not reach significance. Declines in the content of free cholesterol were provoked by progesterone, not by estradiol, in liver microsomes prepared from all feeding groups. No changes in cholesterol 7α-hydroxylase activity and microsomal free cholesterol were observed after administration of the sex hormones for 3 days. Rapid and transient inhibitions in 7α-hydroxylase activity were found after the single injection of progesterone to fed animals. Estradiol, on the contrary, was unable to alter rapidly the hepatic 7α-hydroxylase capacity. It is concluded that: i) estradiol and progesterone act directly on liver microsome membranes inhibiting the activity of cholesterol 7α-hydroxylase, ii) changes in the dietary conditions are important in the in vivo regulation of 7α-hydroxylase by these hormones, and iii) progesterone appears to be an inhibitor of cholesterol 7α-hydroxylase more potent than estradiol.

Progesterone Modulation of Estrogen Receptors in Microdissected Regions of the Rat Hypothalamus

One mechanism whereby progesterone opposes the regulatory actions of estrogen in the brain may include the down-regulation of estrogen receptors. A previous study has shown a small decrease in estrogen binding in the combined preoptic area-hypothalamic area in response to progesterone treatment. To determine if this effect is region specific, gonadectomized/adrenalectomized (GDX/ADX) estrogen-treated female rats were administered a single injection of progesterone (5.0 mg, sc) or a silastic capsule containing crystalline progesterone. Control animals were treated identically but without progesterone exposure. Animals were killed 24 or 72 h after initiating progesterone treatment and estrogen binding was measured in cytosel and cell nuclear extracts of the anterior pituitary, mediobasal hypothalamus (MBH), and preoptic area. A significant effect of progesterone injection on nuclear estrogen binding was observed in the MBH at 24 h. This effect had subsided by 72 h. No effect was observed when progesterone was administered in a continuous fashion. To further examine the regional specificity of the progesterone effect and to determine if males were similarly affected, nuclear-bound estrogen receptors were measured in microdissected brain regions from male and female estrogen-treated GDX/ADX rats treated with 5.0 mg progesterone or vehicle 24 h before sacrifice. A significant decrease in estrogen binding was found in the ventromedial nucleus of the female but not the male. A significant effect of progesterone treatment was found in the periventricular preoptic area of the male. These studies confirm that progesterone acts in the brain to down-regulate estrogen binding and demonstrate that this action is not evenly displayed in all areas of the brain containing high levels of both estrogen and progestin receptors.

Changes in alpha (1-2)-fucosyltransferase activity in the murine endometrial epithelium during the estrous cycle, early pregnancy, and after ovariectomy and hormone replacement.

alpha (1-2)-Fucosyltransferase (alpha (1-2)-FT) activity in the uterine luminal epithelium was investigated during the estrous cycle, during early pregnancy, and in ovariectomized mice treated with ovarian steroids. Phenyl-beta-D-galactoside was used as a specific acceptor for alpha (1-2)-FT activity. Enzyme activity fell dramatically throughout the pre- and peri-implantation period (Days 1-6 of pregnancy). Activity on Day 4 of pregnancy represented less than a tenth of the Day 1 level and by Day 6 became undetectable. During the estrous cycle alpha (1-2)-FT showed a peak of activity at estrus, the level being similar to that observed on Day 1 of pregnancy. In proestrus, postestrus, and diestrus, activity was similar and was approximately one fifth of that during estrus. Ovariectomized mice were primed with estrogen and treated with progesterone only, estradiol benzoate only, or progesterone followed by a single injection of progesterone and estradiol. Estrogen alone stimulated alpha (1-2)-FT activity, while progesterone treatment was strongly inhibitory. These results correlate well with the pattern of expression of the fucosylated H-type-1 carbohydrate epitope found on the endometrial epithelium and believed to have a role in implantation. alpha (1-2)-FT is capable of catalyzing the final step in formation of the H-type-1 oligosaccharide, and on the basis of our results it is likely that control of this enzyme is the major factor responsible for modulating H-type-1 expression.

Studies on Relationship of Biological Rhythms to Reproductive Functions in Animals.

Biochemical, neural, endocrine and behavioral rhythms play a central role in many different aspects of the reproductive process in animals. These rhythms provide the basis for temporal organization of the reproductive functions of individual animals. In this paper, I introduce our results about the relationship of biological clock to reproductive function, analysis of mechanisms in biological clock, and manipulation of circadian rhythms. Main contents are as follows: 1) The ovulation is induced between 14 and 16 hr after stimulation dissociating entirely with solar hours in light estrous rat. The effectiveness of the cervical stimulation for induction of ovulation in light estrous rats is related to not only the duration of light estrus but also the time after transfer to LL. 2) Both nocturnal and diurnal prolactin surges are controlled by a circadian system. 3) Pseudopregnancy is induced by a single injection of progesterone at a special time. 4) The time of parturition and of pre-partum progesterone decrease is closely associated with an endogenous circadian system. 5) Food restriction is more potent zeitgaber than light in circadian adrenocortical rhythms. 6) The circadian rhythms of blinded rat pups is entrained by the nursing dam. 7) Social cues have a profound effect on the synchronization of the free-running period of adrenocortical rhythm. 8) Carbachol, an acetylcholine agonist, shortens the free-running period of circadian activity rhythm. 9) Melatonin accelerates the re-entrainment of the circadian rhythm to shifted LD cycle. 10) Light signals increase the acetylcholine concentration in suprachiasmatic nucleus, but not the other control site. 11) The cAMP levels in rat suprachiasmatic nucleus show an endogenous circadian rhythm. 12) Long term cultured neuron from rat suprachiasmatic nucleus retain the capacity for circadian oscillation of vasopressin release. 13) Inhibitors of protein synthesis phase shift the circadian clock in chick pineal cells.

Inhibitory Effect of Progesterone on Occupied Estrogen Receptors of Anterior Pituitary and Uterus in Adult Rats

Abstract The acute effects of a single progesterone injection on estradiol receptor (E(2)R) binding in the anterior pituitary and uterus were examined in the mature ovariectomized rat. Adult ovariectomized female rats receiving estradiol were injected with various doses of progesterone followed 1 h later by a final injection of 2 mug of estradiol. All animals were sacrificed 1 h after estradiol and the E(2)R binding in the nuclei and cytosol was determined. In the anterior pituitary, progesterone decreased total nuclear E(2)R in a biphasic inhibitory pattern, with maximal effects at 0.8 and 4 mg/kg body wt doses of progesterone and a smaller decrease with the 2 mg/kg body wt dose. This progesterone-induced decrease of nuclear E(2)R was due to a decrease in the occupied form of nuclear E(2)R. The unoccupied nuclear E(2)R and cytosol E(2)R binding were not altered by progesterone administration. In the uterus, progesterone caused a dose-dependent decrease in total nuclear E(2)R binding. This effect also occurred in the occupied form of E(2)R. The uterine unoccupied nuclear E(2)R and cytosol E(2)R were not altered by progesterone administration. These studies emphasize differences in the tissue specificity of progesterone action on occupied nuclear E(2)R which are presumably responsible for the mediation of estradiol action, and provide a biochemical basis for our previous observations of multiphasic effect of progesterone on gonadotropin secretion.

Progesterone receptor concentration differences in the chick oviduct cells and apparent down-regulation by ligand. A semiquantitative immunohistochemical study.

A semiquantitative immunohistochemical technique was developed for identification of chick progesterone receptor (PR). The mouse monoclonal antibody PR6 was used. The nuclear PR concentration was analyzed with Leitz Orthoplan MPV-3 light microscope. The target tissue was chick oviduct, with epithelial, glandular, mesenchymal, smooth muscle and peritoneal cells analyzed separately. PR concentration varied between different cell types and also from cell to cell within a single cell type. A significant decrease of PR concentration, as noted by decrease in staining, was also observed in all studied cell types, 6 h after a single injection of progesterone. This technique allows for histological identification of biochemical events that should help lead to the understanding of the role of PR changes in a variety of experimental situations.