Biomedical subjects

M Jakubowski

Publications and source records attributed to M Jakubowski.

At least 37 records · Page 2Linked to original sources

PubMed1996

Blood lead in the general population in Poland.

Lead concentration in venous blood (Pb-B) was investigated in 1122 inhabitants (including 555 children under 10 years of age) of five Polish towns with no large industrial lead emitters (group I) and in 1246 persons (707 children under 10 years of age) living in the vicinity of zinc and copper mills (group II). The samples were analysed using electrothermal atomic absorption spectrometry (ETAAS) and the performing laboratory participated in the external quality control scheme during the study period (1992-1994). In group I the mean geometric Pb-B concentrations ranged from 23.8 to 48.3 micrograms/l in females, from 42.5 to 76.8 micrograms/l in males and from 29.9 to 62.5 micrograms/l in children. In group II, the mean geometric Pb-B concentrations were significantly higher and ranged from 49.4 to 105 micrograms/l in females, from 98.5 to 149 micrograms/l in males and from 73.7 to 114 micrograms/l in children, the values decreasing as the distance from the source of emission increased. Cigarette smoking was found to bring about a significant increase in Pb-B levels for both males and females. A significant correlation was noted between Pb-B concentrations in mothers and children. The ratio between child and maternal Pb-B concentrations amounted to approximately 1.0 for group I and to about 0.5 for group II. These findings indicate the necessity of undertaking preventive activities over the lead-contaminated areas. However, the lead hazard in Poland seems to be associated with point sources of emission and hence does not concern the whole population.

Adult↗

PubMed1996

Characterization of gonadotropin-releasing hormone gene transcripts in a mouse hypothalamic neuronal GT1 cell line.

We have characterized the nuclear and cytoplasmic RNA transcripts derived from the gonadotropin releasing hormone (GnRH) gene in a mouse hypothalamic neuronal GT1 cell line. Analyses of nuclear GnRH RNA precursors present in the GT1 cells by RNase protection assay show that there is no particular order of intron excision, suggesting the existence of multiple processing pathways. A similar pattern is observed in mouse preoptic area-anterior hypothalamus (POA-AH). In GT1 cells, approximately 5% of the total GnRH RNA transcripts are found in the nucleus. In contrast, in the POA-AH of mice, nuclear transcripts comprise 40% of the total GnRH transcripts. Thus the GT1 cells, while similar in overall GnRH RNA processing to mouse hypothalamic GnRH neurons, do not exhibit the high abundance of nuclear GnRH RNA transcripts seen in the rodent GnRH neuron in vivo. Quantitative analysis of the nuclear RNA species shows that the GnRH primary transcript comprises more than 90% of the total nuclear GnRH mRNA precursors in both GT1 cells and mouse POA-AH and thus GnRH processing intermediates account for fewer than 10% of these precursors. Using these probes, we have examined changes in GnRH primary transcript expression in GT1-7 cells. In the presence of RNA synthesis inhibitors, the half-life of the GnRH primary transcript was found to be quite short, approximately 18 min, suggesting that the level of primary transcript would reflect levels of GnRH gene transcription. When GT1-7 cells are treated with the phorbol ester PMA (phorbol, 12-myristate, 13-acetate) for 1 h, GnRH primary transcript levels decrease by approximately 70%. Supporting the hypothesis that GnRH primary transcript is a good indicator of GnRH gene transcription is the finding that 1 h of PMA treatment results in a similar (approximately 50%) decrease in GnRH gene transcription, as assayed by nuclear run-on assay. Our observation that GT1 cells resemble mouse hypothalamic GnRH neurons in their pattern of intron excision and in the ratio of primary transcript to other nuclear transcripts emphasizes the utility of these cells for studying the regulation of GnRH gene expression in this immortalized hypothalamic cell line.

Animals↗

PubMed1995

Gonadotropin-releasing hormone receptor gene expression in human ovary and granulosa-lutein cells.

GnRH regulates gonadotropin biosynthesis and release in the anterior pituitary via specific receptors. Although extrapituitary expression and action of GnRH have been shown in some species, in the human it is not clear whether GnRH has a peripheral action. In this study we sought to determine whether the human ovary expresses GnRH receptor (GnRHR) messenger ribonucleic acid (mRNA). Ovarian tissues from 11 women (32-61 yr old) and granulosa-lutein (GL) cells purified from follicular aspirates of 51 women undergoing oocyte retrieval for in vitro fertilization were analyzed by ribonuclease protection assay and reverse transcriptase-polymerase chain reaction (RT-PCR). Human pituitaries, lymphocytes, and placenta were also studied. Measurable levels of GnRHR mRNA were found by ribonuclease protection assay in 2 of 10 ovaries, in 2 of 4 GL cells preparations from women whose ovarian hyperstimulation involved a GnRH agonist, in GL cells from 3 women whose ovarian hyperstimulation involved a GnRH antagonist, and in human pituitaries. Relative to the total amount of RNA analyzed, the level of GnRHR mRNA was about 200-fold lower in the ovary than in the pituitary. A sequence of 314 basepairs of GnRHR mRNA was amplified by RT-PCR in the pituitary, in 9 of 10 ovaries, and in 4 of 5 GL cell preparations. No message could be amplified in human lymphocytes, and placental specimens showed a weak signal. The relative GnRHR mRNA levels in GL cells from 13 women analyzed by quantitative RT-PCR showed a wide range of individual differences. These results suggest that GnRHR mRNA is expressed in GL cells and the human ovary across different functional stages, implying that multiple ovarian compartments may express GnRH receptors. The administration of GnRH analogs may have a further direct action on the human ovary.

Adult↗

PubMed1994

Processing of gonadotropin-releasing hormone gene transcripts in the rat brain.

The precursor of gonadotropin-releasing hormone (GnRH) and the 56-amino acid GnRH-associated peptide is encoded in an mRNA of about 560 bases in length. This mRNA derives from an approximately 4300-base pair-long gene consisting of four relatively short exons (denoted 1, 2, 3, and 4) and three large introns (A, B, and C). In this study, we characterized the order by which the three introns are spliced from the primary transcript and processing intermediates to give rise to a mature mRNA and evaluated the potential role of gene transcription and pre-mRNA processing in the control of proGnRH mRNA levels in vivo. Nuclear and cytoplasmic RNA fractions isolated from rat preoptic area-anterior hypothalamus (POA-AH) and basal olfactory area (located rostral to the POA) were analyzed by 1) solution hybridization-RNase protection mapping using several RNA probes directed at various regions of the proGnRH gene and 2) reverse transcription-polymerase chain reaction using several oligonucleotide primers. Both types of analysis showed that proGnRH pre-mRNA processing begins with the splicing of intron B from the primary gene transcript. Hence, intron B is the ideal target for studying proGnRH primary transcript by in situ hybridization. Subsequent splicing of introns A and C appeared to take place in two alternative, although not equally prevalent pathways. Quantitative analysis indicated that the proGnRH hnRNA species constituted, on a mole basis, about 20% of the total gene transcripts in the POA-AH. The primary transcript alone constituted about 10% of the total gene transcripts in the POA-AH and as much as 20% in the basal olfactory area. The prospect of blockade of proGnRH hnRNA processing by means of hybridization with endogenous antisense RNAs (transcribed from the SH gene on the opposite strand of the same DNA locus) did not prove to be likely, as the SH transcripts were present at very low levels compared to any of the proGnRH RNA species. We conclude that the relatively large pool of proGnRH hnRNA may reflect a high rate of gene transcription and/or slow RNA processing.

Animals↗

PubMed1994

Second messenger regulation of mouse gonadotropin-releasing hormone gene expression in immortalized mouse hypothalamic GT1-3 cells.

Using a transgenic mouse derived GnRH expressing neuronal cell line, GT1-3, we studied the effects of activation of cAMP, Ca2+ and protein kinase C pathways by forskolin, ionomycin and the phorbol ester phorbol 12-myristate 13-acetate (PMA), respectively, upon gonadotropin-releasing hormone (GnRH) secretion, cellular peptide content, mRNA and RNA primary transcript levels. Forskolin, ionomycin and phorbol ester all caused an increase in GnRH secretion in GT1-3 cells in a time and dose-dependent manner during a short-term (1 h) static incubation. Prolonged treatment with forskolin (10 microM), ionomycin (1 microM) and PMA (10 nM) for 12 or 24 h resulted in significant decreases in GnRH mRNA levels. Time-course studies showed that the increases in GnRH secretion stimulated by forskolin, ionomycin and PMA were gradually attenuated over time in parallel with the decreases in mRNA expression. In contrast, there were only small and variable changes in the GnRH cellular content. Studies using a GnRH antagonist (100 microM) suggested that the released GnRH has a negative feedback effect on its own secretion. However, co-incubation with the GnRH antagonist did not alter the inhibitory effects on GnRH mRNA levels by the secretagogues. Further studies on the transcriptional effects of forskolin, ionomycin and PMA on GnRH gene expression in GT1-3 cells revealed that all three secretagogues suppressed GnRH RNA primary transcript levels, with forskolin having a slower time course of action. Thus, the inhibition of cytoplasmic GnRH mRNA, and presumably its synthesis, after 12-24 h of secretagogue treatment may be due at least in part to a suppression of GnRH gene transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Human rsk isoforms: cloning and characterization of tissue-specific expression.

Serine-threonine protein kinases in the ribosomal S6 kinase (rsk or p90rsk) family have been implicated as signaling intermediates in the cellular response to several growth factors. To investigate the molecular diversity of human p90rsk isoforms, mixed degenerate oligonucleotide polymerase chain reaction was used to isolate partial rsk cDNAs (1.1 kb). Three closely related human rsk cDNAs were obtained (HU-1, HU-2, HU-3). These cDNAs are encoded by separate genes based on DNA sequence diversity and distinct patterns seen with genomic Southern blots. Northern analysis revealed different sized mRNA transcripts for each isoform. A full-length HU-1 cDNA (3.1 kb) was subsequently isolated from a HeLa cell library. 5'-cDNA clones for HU-2 and HU-3 were isolated using the "rapid amplification of cDNA ends" strategy. Experiments using human x hamster somatic cell hybrids localized the HU-1 gene to human chromosome 3; HU-2 is on chromosome 6; and HU-3 is on the X chromosome. The tissue distribution of human rsk mRNAs was determined using ribonuclease protection assays. HU-3 mRNA was present in multiple RNA samples. HU-2 was expressed in fibroblast > muscle > lymphocyte = placenta > liver. HU-1 was expressed in Epstein-Barr virus lymphocyte > > muscle = liver > fat = placenta. These results indicate that the multiplicity of p90rsk isoforms is increased to at least three for humans and that marked tissue-/cell-specific differences in p90rsk isoform expression are present.

Amino Acid Sequence↗

PubMed1994

The effect of time of day on levels of hypothalamic proopiomelanocortin primary transcript, processing intermediate and messenger ribonucleic acid in proestrous and estrous rats.

Several lines of evidence from different laboratories suggest that hypothalamic beta-endorphinergic activity decreases around the time of initiation of the LH surge and may increase on estrus to extinguish the expression of the daily neuronal signal for the surge. In several hormone systems, factors that stimulate or suppress hormone release also stimulate or repress transcription of the hormone gene and translation of the messenger RNA encoding the hormone. Therefore, information about neurohormone activity may be inferred from data on changes in the levels of RNA species encoding these neurohormones. We used a solution hybridization/RNase protection assay to test the hypotheses that 1) the abundance of primary transcript of the hypothalamic POMC gene decreases at the time of initiation of the proestrous LH surge and 2) levels of POMC primary transcript (and by inference, levels of beta-endorphin neuronal activity and secretion) increase on estrus. 96 rats exhibiting at least two consecutive 4-day estrous cycles were killed at either 0600 or 1300 h on proestrus and estrus. Dissections of the medial basal hypothalamus were pooled into 4 samples at each time-point (6 rats per sample) and RNA was extracted from nuclear and cytoplasmic fractions separately. We measured levels of POMC primary transcript, processing intermediate and fully spliced mRNA in the nuclear fractions and POMC mRNA in cytoplasmic fractions. Compared to 0600 h, levels of POMC primary transcript decreased significantly during the afternoons of both proestrus and estrus (P < 0.05). Levels of nuclear processing intermediate RNA and cytoplasmic mRNA followed the same trend but the afternoon declines did not reach statistical significance. We conclude from these data that the afternoon decline in POMC gene expression is not unique to the day of proestrus and we speculate that an afternoon decline in beta-endorphinergic neuronal activity may instead be a component of the daily signal for the LH surge.

Animals↗

PubMed1994

Occupational exposures to Cd, Ni, and Cr modulate titers of antioxidized DNA base autoantibodies.

This study was undertaken to establish whether occupational exposures to derivatives of carcinogenic metals evoke inflammatory immune responses, as determined by the presence of elevated titers of antibodies (Ab) that recognize oxidized DNA bases. Sera obtained from the blood of steel welders (Delaware) and from workers of the Centra Ni-Cd Battery Factory (Poznań, Poland) were analyzed by the enzyme-linked immunosorbent assay. To determine specific and nonspecific binding, an oxidized thymidine [5-hydroxymethyl-2'-deoxyuridine (HMdU)] coupled to bovine serum albumin (HMdU-BSA) as well as mock-coupled BSA (M-BSA) were used as antigens for coating the wells of microtiter plates. Titers of anti-HMdU Ab were significantly elevated in the high Cd and Ni exposure groups (18.3 +/- 3.2 vs 10.8 +/- 2.1 A492/microliters; p < 0.05). The sera of the groups with low exposures to Cd and Ni also had enhanced titers of those Ab but those increases were not statistically significant. Interestingly, the Ab titers present in the sera of controls for Cd and Ni exposures appear to be constant regardless of the protein content. In contrast, both lightly and heavily exposed subjects exhibited Ab titers that increased with increasing protein content. When 12 randomly selected workers (4 from each of the control, lightly, and heavily exposed groups) were outfitted with personal monitors, anti-HMdU Ab titers of those workers showed a significant difference between the groups with light (< 100 micrograms/m3) and heavy (> 200 micrograms/m3) exposures to Cd (9.8 +/- 3.7 vs 22.1 +/- 3.7 A492/microliters; p < 0.01) and Ni (11.7 +/- 1.4 vs 31.0 +/- 1.8; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen-Antibody Reactions↗

PubMed1993

Kinetics of trichloroethylene elimination from venous blood after acute inhalation poisoning.

The kinetics of trichloroethylene were examined in three men, 28-36 years old, hospitalized after an acute occupational exposure. The trichloroethylene concentration of venous blood was determined by gas chromatography with headspace analysis; urinary trichloroacetic acid was assayed by the colorimetric method of Fujiwara. The kinetics of blood trichlorethylene (t1/2 21.7 h) and the urinary elimination of trichloracetic acid over six days were used to calculate the total inhalation exposures. Blood trichlorethylene was diagnostically more relevant than urinary trichloracetic acid.

Administration, Inhalation↗

PubMed1993

[Biological levels of lead in residents of Poland].

The author discussed current data on sources of the environmental exposure to lead, health effects of exposure in adults and children as well as recommended admissible concentrations of lead in blood. The review of studies on biological monitoring of exposure to lead in Poland permits to state that the results of measurements of Pb-B concentrations performed by laboratories which did not participate in the inter-laboratory programme of quality assurance were often overestimated evoking public concern. The outcome of investigations carried out by the Nofer Institute of Occupational Medicine in Lodz and other institutions which are provided with appropriate analytical equipment, tested under the inter-laboratory programme of quality assurance gives the ground for a hypothesis that an excessive environmental exposure to lead in Poland may result only from industrial emission. The mean geometric lead blood concentrations in persons living in areas free from industrial emissions of lead range from 40 to 70 micrograms/l and they do not prove any potential hazard for adults. Exposure of children and pregnant women living in areas polluted with lead due to industrial emissions and where mean geometric Pb-B concentrations reach 100-170 micrograms/l may create a significant problem. The results obtained emphasize the need for targetted surveillance aimed at identifying areas of excessive lead contamination, measurements of Pb-B concentrations in populations living in those areas and necessary preventive measurements. Collection of blood samples and measurements of lead levels should be performed only by those laboratories which satisfy necessary requirements.

Adolescent↗

PubMed1993

[Evaluation of the usefulness of 2-hydroxypyrene determination in urine and other possible tests for determining exposure to polycyclic aromatic hydrocarbons].

Exposure to airborne polycyclic aromatic hydrocarbons (PAHs) occurring at production of coce and aluminium is one of the major occupational health problems. In workers exposed to airborne PAHs at high concentrations an increased incidence of lung cancer has been found. In the last decade numerous attempts were made to develop methods for the biological monitoring of exposure to this group od compounds. However, some of the methods like determination of thioethers in urine or urinary mutagenicity proved to be influenced to a large extent by cigarette smoking. Determination of 1-hydroxypyrene (1-HP) (pyrene metabolite) in urine seems to be a more promising approach. In a number of investigations relatively good correlation has been found between the concentration of pyrene and PAHs in the air as well as between the level of occupational exposure to pyrene and urinary excretion of 1-HP. The influence of cigarette smoking on the excretion of 1-HP in urine seems to be negligible as compared to the increase in 1-HP excretion in urine resulting from occupational exposure. Further investigations on the kinetics of excretion of 1-HP in urine and the quantitative relationship between the concentration of PAHs in the air and excretion of 1-HP in urine under relatively well controlled conditions are necessary.

Air Pollutants, Occupational↗

PubMed1992

Cadmium availability to the cyanobacterium Synechocystis aquatilis in solutions containing chloride.

Availability of cadmium to Synechocystis aquatilis (estimated by 109Cd sorption and cadmium toxicity-14C method) in solutions containing cadmium and complexing (KCl) or non-complexing (KNO3) salts, in the range of 0-0.5 m was investigated. Both cadmium surface adsorption and transport into the cells were lower in solutions containing cadmium chloride complexes (CdCl+, CdCl2, CdCl3-) than in those containing cadmium in the form of Cd2+. Also, cadmium toxicity in solutions of higher KCl concentrations, in which CdCl+ and CdCl2 forms predominated, was significantly limited.

Journal Article↗

PubMed1992

Positive correlation between proopiomelanocortin and tyrosine hydroxylase mRNA levels in the mediobasohypothalamus of ovariectomized rats: response to estradiol replacement and withdrawal.

We have investigated putative dopaminergic regulation of opiomelanotropinergic activity in the arcuate/periarcuate mediobasohypothalamus (MBH) by assessing the changes in MBH tyrosine hydroxylase (TH; rate-limiting enzyme in catecholamine synthesis) and proopiomelanocortin (POMC; opiomelanotropin precursor) mRNA levels under conditions in which endogenous tuberinfundibular dopaminergic activity exhibits marked changes. Adult Sprague-Dawley rats were sacrificed at 09.00 and 15.00 h, and individual MBH POMC and TH cytoplasmic mRNA levels were simultaneously quantified by multiplex solution hybridization-RNase protection assay with protected fragments separated by polyacrylamide gel electrophoresis. In ovariectomized (OVX) rats treated for 3 days with low-dose estradiol (E2) implants (resulting in 18 +/- 4 pg E2/ml serum), the MBH levels of POMC and TH mRNAs were approximately 17 and 31% lower than those measured in OVX controls, respectively. In OVX rats implanted for 20 days with larger E2 implants (99 +/- 9 pg E2/ml serum), POMC and TH mRNA levels were approximately 29 and 41% lower than in OVX controls, respectively. Additional groups were exposed to the higher E2 dose for 20 days and then killed 10 or 20 days after removal of the E2 implant. In these rats, POMC mRNA levels rebounded to the same level seen in OVX controls, while TH mRNA levels even exceeded control values by 22-27%. TH and POMC mRNA levels did not change significantly between 09.00 and 15.00 h, except 10 days after removal of the E2 implants, when 09.00 h POMC mRNA levels were higher than the 15.00 h levels. MBH POMC and TH mRNA levels were positively correlated with each other within individual animals. This correlation is maintained when both POMC and TH mRNA levels are suppressed in response to both 3-day low-dose and 20-day high-dose E2 treatment. However, although rat MBH opiomelanotropinergic and tuberoinfundibular dopaminergic mRNA biosynthesis thus appear to be positively correlated, the coregulation or functional interactions of these two neuronal systems remain to be determined.

Amino Acid Isomerases↗

PubMed1992

[Neurobehavioral effects of chronic occupational exposure to mixtures of solvents used in furniture varnishing. Part I--Psychological examination].

The study aimed at detecting psychological effects of chronic occupational exposure to the mixtures of solvents used in furniture varnishing. 36 exposed workers and 34 controls selected so as to account for age, education level and the nature work were examined. The following tests were used in the examinations: the Neurobehavioral Core Test Battery, Orebro Symptom Questionnaire, Perceived Stress Scale. A slow-down of perceptive and motor activities, which intensified with the duration of exposure, was the only observed adverse effect of the exposure. The workers employed for periods longer than 15 years more often reported symptoms of psychic function disturbances and deterioration of their health condition.

Adolescent↗

PubMed1992

Integrated index of occupational exposure to cadmium as a predictor of kidney dysfunction.

In a study carried out in an alkaline battery factory, the study group consisted of 141 factory workers exposed to cadmium, while 206 workers in the textile industry constituted the control group. Cadmium in blood (Cd-B), cadmium in urine (Cd-U) as well as beta 2-microglobulin and retinol-binding protein (RBP) in urine were determined. Exposure to cadmium in the factory was high. In 1988, Cd-B concentrations in different departments averaged 11.2-29.9 micrograms/l. To evaluate the admissible period of occupational exposure to cadmium, an integrated exposure index [Cd-B (micrograms/l) x years of exposure] is proposed. According to the dose-response relationship, an increase in low molecular weight protein excretion in urine can be expected in 10% of subjects at an integrated exposure index of about 300 micrograms/l x years of exposure. The data obtained confirmed the validity of the recommended health-based limits for occupational exposure of 10 micrograms/l and 10 micrograms/g creatinine for Cd-B and Cd-U respectively.

Adult↗

PubMed1991

Development of taste organs in Rana temporaria. Transmission and scanning electron microscopic study.

In tadpoles of Rana temporaria two successive generations of taste organs: taste buds (TBs) and taste disks were studied. The TBs are located in the apices of oral premetamorphic papillae. Each TB consists of vertically elongated receptor cells (probably taste) and supporting cells. No basal (Merkel) cells were observed there. Morphologically, two types of receptor cells have been distinguished in a TB. Complete synaptic structures were observed in the TBs between the 30th and 41st of Gosner's (1960) developmental stages, though synaptic vesicles occur already at stage 26. The taste disks consist of taste cells, supporting cells and basal cells. Dense-core synaptic vesicles occur in the gustatory cells at stage 41, but complete synaptic structures were not observed earlier than at stage 45. Synaptic junctions observed at some of the gustatory cells seem to be reciprocal (bidirectional).

Animals↗

PubMed1991

The influence of pH on cadmium toxicity to the green alga Stichococcus bacillaris and on the cadmium forms present in the culture medium.

Cadmium toxicity to the green alga Stichococcus bacillaris was investigated in media of pH 3-9. A significant decrease of cadmium toxicity occurred in both the acidic and alkaline ranges of pH. In media of pH 3 and 9, cadmium did not affect the dry mass content substantially. Maximum toxicity of cadmium was noticed at pH 6-7. Voltametric investigations showed a significant effect of pH on electrochemically measured cadmium content in the culture media. Hydrolysis of the medium components and formation of cadmium complexes with OH(-) ions caused a considerable decrease in amounts of electrochemically measured cadmium in the alkaline range of pH.

Journal Article↗

PubMed1991

Postnatal development of gonadotropin-releasing hormone and cyclophilin gene expression in the female and male rat brain.

The rat preoptic area-anterior hypothalamic continuum (POA-AH) contains about 400-800 neurons that express the decapeptide GnRH and the 56-amino-acid GnRH-associated peptide. Originating from the olfactory placode, these neurons migrate and establish their final distribution and connections in the POA-AH several days before birth. The aim of the present study was to examine whether the biosynthesis of the mRNA encoding the precursor (proGnRH) common to GnRH and GnRH-associated peptide undergoes postnatal changes corresponding to the development of sexual maturation. The POA-AH content of proGnRH messenger RNA (mRNA) was followed from postnatal day 1 to day 90 in female and male Sprague-Dawley rats killed by decapitation between 1000-1200 h. Cytoplasmic RNA fractionated from individual POA-AH homogenates was purified using proteinase K digestion. Cytoplasmic proGnRH mRNA was quantitated simultaneously with cyclophilin mRNA (an internal standard control) using solution hybridization-RNase protection assay, with the protected fragments separated through polyacrylamide gel electrophoresis. In the POA-AH, the concentrations of proGnRH mRNA (femtograms mRNA per microgram total RNA) increased significantly with age in both sexes (P less than 0.001). In males, proGnRH mRNA levels increased by day 30 some 2-fold over the values of days 5 and 10, and the levels established on day 30 were maintained through adulthood. In females, the first rise in proGnRH mRNA levels occurred on day 30, followed by an additional increase on day 45 to levels seen in adulthood. Levels of proGnRH mRNA established in adulthood were significantly higher in females than in males (P less than 0.03). The concentrations of cyclophilin mRNA (picograms mRNA per microgram total RNA) remained essentially unchanged in both sexes during the same period of time when proGnRH mRNA levels were increasing. These results provide evidence for postnatal sex-related increases in the levels of proGnRH mRNA in the rat POA-AH, which are likely to reflect differential regulation by gonadal steroids.

Amino Acid Isomerases↗