Photoperiodicity and increasing salinity as environmental cues for reproduction in desert adapted rodents

Understanding the ways environmental signals, regulate reproduction and reproductive behavior of desert adapted rodents is a major gap in our knowledge. In this study, we assessed the roles of photoperiod and diet salinity, as signals for reproduction. We challenged desert adapted common spiny mice, Acomys cahirinus, males and females with osmotic stress, by gradually increasing salinity in their water source - from 0.9% to 5% NaCl under short and long days (SD and LD, respectively). Photoperiodicity affected testosterone levels, as under LD-acclimation, levels were significantly (p<0.05) higher than under SD-acclimation. Salinity treatment (ST) significantly reduced SD-acclimated male body mass (W(b)) and testis mass (p<0.005; normalized to W(b)). ST-LD-females significantly (p<0.005) decreased progesterone levels and the numbers of estrous cycles. A reduction in white adipose tissue (WAT) to an undetectable level was noted in ST-mice of both sexes under both photoperiod regimes. Receptors for vasopressin (VP) and aldosterone were revealed on testes of all male groups and on WAT in control groups. Our results suggest that photoperiod serves as an initial signal while water availability, expressed by increased salinity in the water source, is an ultimate cue for regulation of reproduction, in both sexes of desert-adapted A. cahirinus. We assume that environmental changes also affect behavior, as water seeking behavior by selecting food items, or locomotor activity may change in extreme environment, and thus indirectly affect reproduction and reproductive behavior. The existence of VP and aldosterone receptors in the gonads and WAT suggests the involvement of osmoregulatory hormones in reproductive control of desert adapted rodents.

In vitro mitochondrial effects of PK 11195, a synthetic translocator protein 18 kDa (TSPO) ligand, in human osteoblast-like cells

The role of the TSPO in metabolism of human osteoblasts is unknown. We hypothesized that human osteoblast metabolism may be modulated by the TSPO. Therefore we evaluated the presence of TSPO in human osteoblast-like cells and the effect of its synthetic ligand PK 11195 on these cells. The presence of TSPO was determined by [(3)H]PK 11195 binding using Scatchard analysis: Bmax 7682 fmol/mg, Kd 9.24 nM. PK 11195 did not affect significantly cell proliferation, cell death, cellular viability, maturation, [(18)F]-FDG incorporation and hexokinase 2 gene expression or protein levels. PK 11195 exerted a suppressive effect on VDAC1 and caused an increase in TSPO gene expression or protein levels. In parallel there was an increase in mitochondrial mass, mitochondrial ATP content and a reduction in ΔΨm collapse. Thus, it appears that PK11195 (10(-5) M) stimulates mitochondrial activity in human osteoblast-like cells without affecting glycolytic activity and cell death.

Designing a long-acting human growth hormone (hGH) by fusing the carboxyl-terminal peptide of human chorionic gonadotropin beta-subunit to the coding sequence of hGH

Chimeric genes were constructed by fusing of human GH (hGH) cDNA to one, two, or three cassettes of the carboxyl-terminal peptide (CTP) of human chorionic gonadotropin (hCG)-beta-subunit. hGH variant genes were inserted into the pCI-DHFR plasmid, transfected into DG44 cells, and stable clones were selected. Bioactivity and pharmacokinetic studies were performed in hypophysectomized Sprague Dawley derived male rats. The results indicated that sc injections of GH-wild-type (WT), Biotropin (commercial), GH-CTP, or CTP-GH (0.6 mg/kg) once every 5 d for 11 d (total dose of 1.2 mg/kg) resulted in an increased weight gain by 4, 4.9, 5.1, and 7 g, respectively. Treatment with CTP-GH-CTP-CTP (GH-LA) or CTP-GH-CTP (0.6 mg/kg) once every 5 d for 11 d or with Biotropin (0.12 mg/kg) daily for 11 d (total dose 1.2 mg/kg) resulted in a dramatic increase in weight gain of 16.5, 16.8, and 17 g, respectively. Repeated injections with different doses of GH-LA, 0.6, 1.8 mg/kg every 4 d or daily injection of 0.12 mg/kg of Biotropin increased the weight gain by 16, 28, and 18 gr, respectively. In addition, the cumulative serum levels of IGF-I after injection of GH-LA was significantly higher than that detected after injection of Biotropin. Pharmacokinetic studies indicated that the half-life, mean residence time, area under the curve, time of maximal plasma concentration, and maximal plasma concentration of GH-LA are dramatically increased compared with Biotropin. This may suggest that the mechanism of GH metabolic clearance is affected by the presence of CTP. These data establish a rationale for using this chimera as a long-acting GH analog.

Effect of increased dietary salinity on the reproductive status and energy intake of xeric and mesic populations of the spiny mouse, Acomys

The possible role of increased dietary salinity as a proximate regulator of reproduction in xeric population of golden spiny mice (Acomys russatus) and mesic population of common spiny mice (A. cahirinus) was tested. In the wild, as the dry season progresses, evaporative water loss in the vegetation increases. This leads to increase in particle concentration of plant tissues. Thus, species consuming a plant diet are exposed to increased dietary salinity. Both male and female individuals of A. russatus were subjected to gradually increasing dietary salinity (0.9%, 2.5%, 3.5%, and 5%) while those of A. cahirinus only up to 3.5% for a total period of 8 and 6 weeks, respectively. Urine osmolarity showed a significant increase under 3.5% and 5% salinity in A. russatus and 2.5% and 3.5% in A. cahirinus. Testis mass and spermatogenesis were significantly reduced while uterine mass and vaginal estrus cycles were not affected in A. russatus. None of the parameters was significantly affected in A. cahirinus. Increase in salinity also significantly reduced body mass in A. russatus but not in A. cahirinus. Mass-specific daily digestible energy intake was not significantly affected by increased salinity in both species. Recovery individuals regained body mass quickly and surpassed initial values after four weeks. However, testis mass and spermatogenesis did not show recovery. The results suggest that increase in dietary salinity could be used as a proximate signal to regulate reproduction in A. russatus by halting it in males, as the dry season progresses while such role in the mesic population of A. cahirinus is unlikely.

Development of a long-acting erythropoietin by fusing the carboxyl-terminal peptide of human chorionic gonadotropin beta-subunit to the coding sequence of human erythropoietin

Human erythropoietin (EPO) is a glycoprotein hormone secreted from the kidney and controls red blood cell production. EPO has a wide clinical use in the treatment of anemia associated with renal disease, certain chronic diseases, and anemia related to chemotherapy and radiotherapy. One major issue regarding the clinical use of EPO is its relatively short half-life due to its clearance by glomerular filtration. Thus, the therapeutic protocol used in the treatment of patient-required frequent injections of EPO. To address this issue, we constructed a chimeric gene that contains the sequence of the carboxyl-terminal peptide (CTP) of human chorionic gonadotropin-beta subunit bearing four O-linked oligosaccharide recognition sites and the coding sequence of human EPO cDNA. Fusing the CTP to the carboxyl-terminal of EPO did not affect secretion, receptor binding affinity, or in vitro bioactivity. However, both in vivo potency and half-life of EPO-CTP were significantly enhanced. A single injection dose (660 IU/kg) of EPO wild-type administered once a week had no significant effect on haematocrit levels. However, EPO-CTP administered as 660 IU/kg once a week was effective as well as the same total dose of EPO wild-type administered as 220 IU/kg three times a week. This may emphasize the importance of sustained blood levels rather than total dose of administration for in vivo bioactivity. These data established the rationale for using this chimera as a long-acting EPO analog. The therapeutic efficacy of EPO-CTP analog needs to be established in higher animals and human clinical trials.

Clinical significance of the parental origin of the X chromosome in turner syndrome

CONTEXT

The phenotype in Turner syndrome (TS) is variable, even in patients with a supposedly nonmosaic karyotype. Previous work suggested that there were X-linked parent-of-origin effects on the phenotype.

HYPOTHESIS

The TS phenotype is influenced by the parental origin of the missed X chromosome.

DESIGN

This was a multicenter prospective study of TS patients and both their parents, determining parental origin of the X-chromosome, and characterizing the clinical phenotype.

PATIENTS AND METHODS

Eighty-three TS patients and their parents were studied. Inclusion criteria were TS with karyotype 45,X or 46Xi(Xq). Four highly polymorphic microsatellite markers on the X-chromosome DMD49, DYSII, DXS1283, and the androgen receptor gene and three Y chromosome markers, SRY, DYZ1, and DYZ3.

OUTCOME MEASURES

The study determined the correlation between the parental origin of the X chromosome and the unique phenotypic traits of TS including congenital malformations, anthropometry and growth pattern, skeletal defects, endocrine traits, education, and vocation.

RESULTS

Eighty-three percent of 45,X retained their maternal X (X(m)), whereas 64% 46Xi(Xq) retained their paternal X (X(p), P < 0.001). Kidney malformations were exclusively found in X(m) patients (P = 0.030). The X(m) group had lower total and low-density lipoprotein cholesterol (P < 0.003), and higher body mass index sd score (P = 0.030) that was not maintained after GH treatment. Response to GH therapy was comparable. Ocular abnormalities were more common in the paternal X group (P = 0.017), who also had higher academic achievement.

CONCLUSIONS

The parental origin of the missing short arm of the X chromosome has an impact on overweight, kidney, eye, and lipids, which suggests a potential effect of an as-yet-undetermined X chromosome gene imprinting.

The role of O-linked and N-linked oligosaccharides on the structure-function of glycoprotein hormones: development of agonists and antagonists

Thyrotropin (TSH) and the gonadotropins; follitropin (FSH), lutropin (LH) and human chorionic gonadotropin (hCG) are a family of heterodimeric glycoprotein hormones. These hormones composed of two noncovalently linked subunits; a common alpha and a hormone specific beta subunits. Assembly of the subunits is vital to the function of these hormones. However, genetic fusion of the alpha and beta subunits of hFSH, hCG and hTSH resulted in active polypeptides. The glycoprotein hormone subunits contain one (TSH and LH) or two (alpha, FSHbeta and hCGbeta) asparagine-linked (N-linked) oligosaccharides. CGbeta subunit is distinguished among the beta subunits because of the presence of a carboxyl-terminal peptide (CTP) bearing four O-linked oligosaccharide chains. To examine the role of the oligosaccharide chains on the structure-function of glycoprotein hormones, chemical, enzymatic and site-directed mutagenesis were used. The results indicated that O-linked oligosaccharides play a minor role in receptor binding and signal transduction of the glycoprotein hormones. In contrast, the O-linked oligosaccharides are critical for in vivo half-life and bioactivity. Ligation of the CTP bearing four O-linked oligosaccharide sites to different proteins, resulted in enhancing the in vivo bioactivity and half-life of the proteins. The N-linked oligosaccharide chains have a minor role in receptor binding of glycoprotein hormones, but they are critical for bioactivity. Moreover, glycoprotein hormones lacking N-linked oligosaccharides behave as antagonists. In conclusion, the O-linked oligosaccharides are not important for in vitro bioactivity or receptor binding, but they play an important role in the in vivo bioactivity and half-life of the glycoprotein hormones. Addition of the O-linked oligosaccharide chains to the backbone of glycoprotein hormones could be an interesting strategy for designing long acting agonists of glycoprotein hormones. On the other hand, the N-linked oligosaccharides are not important for receptor binding, but they are critical for bioactivity of glycoprotein hormones. Deletion of the N-linked oligosaccharides resulted in the development of glycoprotein hormone antagonists. In the case of hTSH, development of an antagonist may offer a novel therapeutic strategy in the treatment of thyrotoxicosis caused by Graves' disease and TSH secreting pituitary adenoma.

Paternal isodisomy of chromosome 7 with cystic fibrosis and overgrowth

We have diagnosed a boy with cystic fibrosis (CF) due to paternal UPD presenting with overweight and developmental delay, not typical features to CF patients. Two previously reported patients with paternal UPD(7) did not present overgrowth. The discrepancy between the phenotype of this boy and the other two patients raises the question of imprinted genes or homozygotization of a disease-causing gene in paternal UPD7.

Arsenic Trioxide inhibits the growth of human ovarian carcinoma cell line

OBJECTIVE

To determine whether Arsenic Trioxide may be an effective treatment of human ovarian carcinoma, we examined if it induced apoptosis in human ovarian cancer cell line.

METHODS

The human ovarian cell line SKOV3 was exposed to different concentrations of As2O3: 0 (control), 0.1 microM, 1 microM, 5 microM and 10 microM. The effect on cells proliferation and apoptotic parameters was examined.

RESULTS

The most effective inhibitory Arsenic Trioxide concentrations were 5 microM and 10 microM, causing growth inhibition of 79% and 83%, respectively. The maximum inhibitory effect of Arsenic Trioxide on cellular proliferation was seen after 48 h. No morphological or molecular features of apoptosis have been observed. At the same time, there were no typical changes of cellular necrosis.

CONCLUSIONS

The exact mechanism by which Arsenic Trioxide inhibits the growth of ovarian cancer cells is probably not by apoptosis. However, since As2O3 has been shown to inhibit ovarian cancer cellular growth, it should be further elucidated as a possible chemotherapeutic agent of ovarian cancer.

Differences in the characteristics of families with BRCA1 and BRCA2 mutations in Israel

Three specific mutations in the BRCA1 (185delAG, 5382insC) and BRCA2 (6174delT) genes have been reported to be of high prevalence in the Jewish Ashkenazi population. We studied the differences in phenotype of families carrying these mutations. All consecutive families found by the CHS Familial Cancer Service to carry one of the three 'Jewish' mutations of the BRCA1/BRCA2 genes were evaluated for phenotypic characteristics. Chi-squared and Student's t-test statistics were employed to study differences in a variety of clinical and demographic parameters. A total of 111 families with 1499 family members were included. Among them 454 cases of cancer (297 in breast/ovary) were reported. Ovarian cancer, but not breast cancer, was detected at a significantly younger age among carriers of 185delT compared with other mutation carriers. In families with 185delAG, 5382insC and 6174delT mutations, breast cancer was found in 20.2, 39.4 and 24.1% of all identified women (born between 1900 and 1975), correspondingly. The corresponding figures for ovarian cancer were 13.9, 6.8 and 4.9%. Families carrying the 5382insC mutation had the highest probability of expressing bilateral breast cancer (38.9% of families, 15.4% of women with cancer, 6.1% of all women in family) and metachronous breast and ovary tumours (22.2, 9.8 and 4.5% correspondingly). Other tumours were reported in 7.9, 9.1 and 12.0% of women and 9.5, 12.9 and 15.8% of men in families with 185delAG, 5382insC, 6174delT, correspondingly. Marked phenotypic differences were found between families carrying different BRCA mutations warranting mutation-specific counselling to families seeking risk-reduction advice. 5382insC emerged as a most aggressive mutation.

Human thyrotropin (TSH) variants designed by site-directed mutagenesis block TSH activity in vitro and in vivo

TSH is a heterodimeric glycoprotein hormone synthesized in the pituitary and composed of a specific beta-subunit and a common alpha-subunit shared with FSH, LH, and human chorionic gonadotropin. The heterodimer was previously converted into a biologically active single chain protein by genetic fusion of the genes coding to both subunits in the presence of the carboxy-terminal sequence of human (h) chorionic gonadotropin-beta subunit as a linker [hTSHbeta-carboxyl-terminal peptide (CTP)-alpha]. N-linked carbohydrate-free single-chain TSH variants were constructed by site-directed mutagenesis and overlapping PCR: one devoid of both N-linked oligosaccharide chains on the alpha-subunit (hTSHbeta-CTP-alpha(deg)) and the other lacking also the oligosaccharides on the beta-subunit (hTSHbeta(deg)-CTP-alpha(deg)). These variants were expressed in Chinese hamster ovary cells and secreted into the culture media. We have previously reported that the variants block the activities of hTSH and thyroid-stimulating immunoglobulins in cultured human thyroid follicles. In the present study, binding affinity of hTSH variants to hTSH receptor and the localization of the antagonistic effect were examined. Moreover, the effect of these variants on TSH activity was tested in vivo. The results of the present study indicate that the hTSH variants bind to the hTSH receptor with high affinity. Experiments using forskolin also indicated that the N-linked carbohydrate-free TSH single-chain variants inhibit TSH activity at the receptor-binding site and not at a postreceptor level. Moreover, the variants significantly inhibited (about 50%) TSH activity with respect to thyroid hormone secretion in vivo in mice. These variants may offer a novel therapeutic strategy in treating hyperthyroidism.

Identification of two mutations for ataxia telangiectasia among the Druze community

Ataxia telangiectasia (AT) is a rare autosomal recessive disease characterized by progressive cerebellar ataxia, immunodeficiency, susceptibility to lymphoreticular malignancies and cancer predisposition, hypersensitivity to ionic radiation and chromosomal instability. In this study, we report a founder effect of AT with two different mutations: 1339 C > T and 6672 del GG together with 6677 del TACG, found in four Israeli Druze clans originating from three different Druze centers in the Middle East (Lebanon, Syria and Jordan). The 1339 C > T mutation, which results in a stop codon at position 447 of the ATM protein, was observed in two unrelated clans originating from Lebanon and Jordan. The 6672 del GG/6677 del TACG mutation was observed in two unrelated clans originating from Syria and Lebanon. In the present study, simple and fast detection assays were developed for both mutations. The ability to identify AT carriers routinely provides a unique opportunity for prenatal diagnosis, genetic counseling as well as marriage guidance in the Druze community.

Evaluation of the spectral transmittance of UV-absorbing disposable contact lenses

PURPOSE

Increasing evidence suggesting deleterious effects of ultraviolet radiation (UVR) on the eye has prompted manufacturers to develop UV-absorbing disposable contact lenses. The spectral transmittances of a sample of these lenses were measured in order to determine if they provide adequate protection from UVR.

METHODS

Four types of UV-absorbing disposable lenses were studied (Acuvue [Vistakon, Jacksonville, FL], Precision UV [Wesley-Jessen, Des Plaines, IL], Specialty Sport [Specialty UltraVision, Sunnyvale, CA], and Surevue [Vistakon]). For comparison, a lens without UV-absorbing properties (Acuvue), a conventional soft lens (Permaflex UV [Cooper Vision, San Jose, CA]) and an RGP lens (Boston ES [Polymer Technology, Rochester, NY]) were also evaluated. The tested lens was placed in a silica wet cell filled with saline. Spectral transmittance was measured over the 200-800 nm waveband.

RESULTS

Each disposable lens exhibited a transmittance window in the 240-320 nm waveband. Computing indices of protection factor and safe exposure duration allowed for the assessment of the level of protection afforded by each lens. Among disposable lenses studied, the Surevue performed best with a transmittance of less than 1% in the waveband 280-348 nm and the longest safe exposure duration, while the Specialty Sport had the highesttransmittance of UVB (290-315 nm).

CONCLUSION

All UV-absorbing lenses studied provided a better level of protection from UVR exposure than lenses without UV absorber. These results will help the eyecare practitioner in prescribing the most appropriate UV-blocking lens for each patient.

DNA global hypomethylation in EBV-transformed interphase nuclei

In tumors, DNA is often globally hypomethylated compared to DNA extracted from normal tissues. This observation is usually made after extraction and exhaustive digestion of DNA followed by analysis of nucleosides by chromatography or digestion with restriction enzymes, gel analysis, and hybridization. This approach provides an average value which does not give information on the various cell subpopulations included in heterogeneous samples. Therefore an immunochemical technique was set up with the aim of demonstrating, in a population of mixed cells, the possibility of detecting the presence of individual nuclei containing hypomethylated DNA, on a cell-by-cell basis. Monoclonal antibodies to 5-methylcytidine were used to label cells grown in vitro. Under appropriate fixation and permeabilization conditions, interphase nuclei were labeled. Quantitative differences in the labeling were detected between Epstein-Barr virus-transformed cells and normal peripheral blood monocytes by flow cytometry analysis. Similar differences were observed by fluorescence microscopy. Both results were confirmed by Southern transfer and hybridization of DNA fragments generated by restriction enzyme digestion. This observation, which is in accordance with the occurrence of global DNA hypomethylation in tumors as established by chromatography, opens the field for the analysis of fresh tumor samples by flow cytometry and microscopy.

High Epstein-Barr virus serum load and elevated titers of anti-ZEBRA antibodies in patients with EBV-harboring tumor cells of Hodgkin's disease

Hodgkin's disease is commonly associated with EBV latent infection. The incidence of EBV reactivation (active infection or EBV infection with replicative cycle) was evaluated in a series of 30 patients with untreated Hodgkin's disease (except for one case with chronic lymphocytic leukemia) by quantitation of EBV DNA and titration of anti-ZEBRA antibodies in serum samples. DNA was detected in serum (>2.5 x 10(2) genomes/ml) in 15 of 30 patients and was more frequent in Hodgkin's disease with EBV-positive Reed-Sternberg cells (10/12) than in EBV-negative cases (5/18), (P< 0.01). Of interest was the demonstration that viremia correlated well with increased titers of anti-ZEBRA IgG and/or standard serological profiles of EBV reactivation (12/15), (P < 0.05). However the lack of EBV replicative cycle in Reed-Sternberg cells (negative for ZEBRA antigen and early antigen BHLF1) suggests that the viral replication occurs in a nonneoplastic cell compartment rather than in tumor cells. The measurement of EBV DNA loads and the titration of anti-ZEBRA antibodies shed new lights on the link between activation of EBV replication and Hodgkin's disease: these serological markers together with the determination of the EBV status of the tumor suggest that replication of the viral genome occurs with a decreased efficiency of the immune system, thus allowing progression of the tumor.

In situ amplification of the Epstein-Barr virus genome in cell suspensions

Epstein-Barr virus (EBV) is distributed widely throughout the world. Apart from a association with two geographically-restricted malignancies (Burkitt's lymphoma and nasopharyngeal carcinoma), EBV is thought to be implicated in the etiology of B-cell lymphoma in immunocompromised individuals. In these patients, monitoring the viral load in serum can provide useful information on the timing of the instigation of antiviral therapy, i.e. as soon as a rise is detected. PCR technology, owing to its high sensitivity, is used frequently in such situations. In order to gain further insight into the nature of the peripheral blood cells carrying the viral genome on a cell-by-cell basis, an in situ amplification technique was developed as a model using two cell lines growing in suspension, with the aim of distinguishing between EBV-positive and EBV-negative cells. Preliminary experiments were undertaken subsequently on clinical samples from patients with infectious mononucleosis and patients with lymphoma indicating that this technique might be useful clinically.

Characterization of the O-glycosylation sites in the chorionic gonadotropin beta subunit in vivo using site-directed mutagenesis and gene transfer

Human chorionic gonadotropin (CG) is a member of a family of glycoprotein hormones which are heterodimers containing two nonidentical subunits: a common alpha and a hormone-specific beta subunit. One of the distinguishing features of the CGbeta subunit is the presence of four serine acceptors clustered within the last 25 amino acids. We previously demonstrated that this carboxyl-terminal region is important for maintaining its biologic half-life, and when the sequence was genetically fused to either the common alpha or follitropin beta subunits, O-glycosylation was observed. Because this carboxyl-terminal sequence is located at the end of the subunit, we considered this region a convenient in vivo model for studying O-linked glycosylation in domains containing multiple serine recognition sites. A CGbeta gene was engineered in which the N-linked sites were inactivated to eliminate background from those carbohydrate groups. Using this construct, we made a series of truncation and amino acid substitutions of acceptor serines, and these mutants were transfected into Chinese hamster ovary cells. O-Glycosylation was determined by [3H]glucosamine incorporation and glycanase sensitivity of the products on SDS-polyacrylamide gels. We show that the O-linked sites comprise independent repetitive regions in which each acceptor serine has a recognition signal bounded by the next carboxy acceptor serine within four to five amino acids. It is also apparent that recognition of one site is not dependent on the glycosylation of another acceptor. Amino acid mutations in the acceptor regions demonstrated the importance of proline as a necessary feature for O-linked recognition in the CGbeta sequence.

Polymerase chain reaction products containing 5-methyldeoxycytidine: a microplate immunoquantitation method

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Modulation of peripheral benzodiazepine receptors in female rat genital organs by various gonadal steroids

Peripheral benzodiazepine receptors (PBR) in the ovary, oviduct, uterus, and kidney of immature rats were studied under short- and long-term treatment with testosterone (T), progesterone (P4), and diethylstilbestrol (DES). A significant increase in PBR specific binding was observed after 4 days' treatment with T in the ovary (1.6-fold), oviduct (2.0-fold), and uterus (1.4-fold) compared with intact rats. Four days' treatment with P4 increased PBR specific binding in the ovary (1.5-fold), but no changes were detected in the oviduct or uterus. In contrast, PBR specific binding was significantly reduced by 10 days' treatment with T or P4: 40 and 12%, respectively, in the ovary and 35 and 40%, respectively, in the oviduct. Ten days' treatment with T reduced PBR specific binding in the uterus by 25%, but the same interval of treatment with P4 did not alter specific binding in the uterus. Four or 10 days' treatment with DES significantly increased PBR specific binding in the ovary (1.5-fold), oviduct (2.4-fold), and uterus (1.9-fold). Scatchard analysis revealed that the changes in the PBR specific binding were due to a change in PBR density values rather than PBR affinity values. No change in PBR specific binding was found in the kidney following any of these treatments. Taken together, it is suggested that PBR density in the ovary is altered by exogenously administered steroids that usually are biosynthesized in the ovary. Additionally, the altered PBR density in the oviduct and uterus via the various steroids employed may imply that changes occurring in ovarian steroidogenesis should affect PBR density in these organs.

Hippocampal gamma-aminobutyric acid and benzodiazepine receptors after early phenobarbital exposure

Mice were exposed to phenobarbital (PhB) prenatally (PreB offspring) by feeding their mothers 3 g/kg PhB in milled food on gestation days 9-18, or neonatally by directly injecting pups of intact mothers with daily dose of 50 mg PhB on postnatal days 2-21 (NeoB offspring). At age 22 or 50 days, the offspring were tested for gamma-aminobutyric acid (GABA) up take in the hippocampus and in the rest of the brain. In addition, [3H]muscimol and [3H]flunitrazepam binding in the hippocampus and cortex were measured in the offspring at age 22 and 50 days. Long-term decrease in GABA uptake was found in the NeoB group. A 23% decrease was found in 22-day-old mice (P < 0.001) and a 22% decrease in 50-day-old mice (P < 0.05). In addition, there was a 22% decrease in GABA uptake in the brain of 22-day-old PreB mice (P < 0.05). An increase of 52% in [3H]muscimol binding (P < 0.001) and 45% (P < 0.001) in [3H]flunitrazepam binding were measured in the hippocampus in the 22-day-old NeoB mice; no differences were found in affinity. The differences were short-term and could no longer be detected at age 50 days. No differences were found in the cortex; unlike NeoB, PreB mice did not differ from controls. The results suggest upregulation of the GABAergic system in early PhB exposed mice.