Perinatal developmental changes in expression of the neuropeptide genes preoptic regulatory factor-1 and factor-2, neuropeptide Y and GnRH in rat hypothalamus.

The preoptic regulatory factor genes, PORF-1 and PORF-2, are expressed in the rat brain in a regional-, age- and gender-dependent fashion. They are also expressed in the testis, where PORF-2 mRNA localizes to dividing germ cells while PORF-1 mRNA is associated with newly differentiated sperm. This suggests that PORF-1 and PORF-2 may play distinct roles in cell growth and differentiation. Moreover, the two preoptic regulatory factors are also highly expressed in the immature and mature rat hypothalamus, and their expression is modulated by gonadal hormones. Therefore, in the present study we investigated the expression of these two factors in neuroendocrine regions of the developing rat brain by addressing the following questions. First, are PORF-1 and PORF-2 mRNAs expressed during perinatal development in the preoptic area-anterior hypothalamus (POA-AH) and medial basal hypothalamus (MBH), and how do their levels vary? Second, are there gender differences in their expression? We also compared expression of the PORF mRNAs with those of neuropeptide Y (NPY) and gonadotropin-releasing hormone (GnRH), which play critical neuroendocrine roles, in these brain regions. PORF-1, PORF-2, and NPY mRNAs in the POA-AH and MBH, and GnRH mRNA in the POA-AH, were quantified by RNase protection assay at embryonic day (E) 18-19, and postnatal days (P) 0, 5, 10 and 15 in male and female rats. The results show that the four neuropeptide genes are regulated differentially during the perinatal-prepubertal period. PORF-1 mRNA shows age-related increases in expression from E18-E19 to P15 in POA-AH and MBH, without significant gender differences. In contrast, PORF-2 mRNA shows both age and gender differences in expression in these brain regions, with decreases occurring during the same time period in development. NPY mRNA increases similarly in males and females with age in POA-AH and MBH during this period. GnRH mRNA does not change during this period. Taken together with previous studies, the results suggest possible roles for PORF-1 and NPY in the pubertal process, since their expression is maximal from the prepubertal to the early pubertal period. The observation of highest levels of expression of PORF-2 in embryonic neuroendocrine tissues suggests a possible involvement of this neuropeptide in prenatal/neonatal developmental events.

Differential gene expression response to gonadal hormones by preoptic regulatory factors-1 and -2 in the female rat brain.

Steroids and neuropeptides interact in the central nervous system (CNS) to regulate reproductive function and behavior. The preoptic regulatory factors, PORF-1 and PORF-2, are unique neuropeptides for which roles in gender-related brain development and function have been proposed. PORF-1 and PORF-2 expression in rat brain are age, region and gender dependent, and castration or hypophysectomy alter the metabolism of the PORF-1 and PORF-2 mRNAs in male rat brain and testes. If these two peptides have a role in gender-dependent brain function, then gonadal steroids might well affect their expression. The present study was designed to investigate the response of the PORF-1 and PORF-2 mRNAs to sex steroids in the female rat brain and to compare this response to that of two peptides whose roles in the neuroendocrinology of reproduction are well established, gonadotropin-releasing hormone (GnRH) and neuropeptide Y (NPY). Rats were ovariectomized and treated with placebo, estradiol (E2), progesterone (P4) or a combination of the two (E2/P4) and NPY, PORF-2, GnRH and PORF-1 mRNAs were quantified by nuclease protection assays. PORF-1, PORF-2 and GnRH mRNAs were also measured in intact rats during estrus and proestrus. Responses were compared in the preoptic anterior hypothalamus (POA), medial basal hypothalamus (MBH), cerebral cortex (CC) and hippocampus (HIPP). Expression of PORF-1 and PORF-2 was also confirmed in the female rat hypothalamus by in situ hybridization analysis. PORF-1 and PORF-2 mRNAs were detected in the adult female rat brain by both in situ hybridization and ribonuclease protection analyses. In situ hybridization analysis demonstrated that PORF-1 and PORF-2 mRNAs are expressed in hypothalamic neurons. RNase protection analysis showed that PORF-1, PORF-2 and NPY mRNAs were present in all four brain regions examined while GnRH expression was detected only in the MBH and POA. Estradiol alone upregulated expression of the PORF-1 and PORF-2 mRNAs in the ovariectomized rat in the POA and HIPP, and of NPY mRNA in the MBH and HIPP. Progesterone alone had a stimulatory effect on NPY mRNA in the MBH and HIPP. Treatment with a combination of E2/P4 downregulated PORF-2 mRNA in the POA as well as PORF-1, PORF-2 and NPY mRNAs in the CC. In contrast, E2/P4 upregulated the PORF-2 and NPY mRNAs in the HIPP and NPY mRNA in the MBH. In the cycling rat, PORF-1 mRNA levels were higher during proestrus than estrus in both the MBH and POA, while PORF-2 mRNA levels did not change. In contrast GnRH mRNA was lower in the POA and higher in the MBH during proestrus compared with estrus. Thus, intrinsic factors, most likely both ovarian and neuroendocrine, regulate PORF-1 and GnRH expression in the intact cycling rat CNS in a region-dependent manner. In the ovariectomized rat, PORF-1, PORF-2, NPY and GnRH mRNAs all respond in a region-specific manner to sex steroid treatment. These data support the role of PORF-1 and PORF-2 in gender-dependent brain function in the adult female rat.

Modulation of preoptic regulatory factor-2 (porf-2) mRNAs by castration and hypophysectomy.

Neuropeptides are central to the regulation of mammalian gender-dependent development and reproduction. Preoptic regulatory factor-2 is a neuropeptide gene that is known to be expressed in rat brain and testis. In the brain, expression is gender-dependent and age-dependent. Tissue-specific transcripts are found in the preoptic area (POA) of the hypothalamus and in the testis. In order to investigate the effects of reproductive hormone status on expression of porf-2 in the male rat, porf-2 transcripts were studied by Northern blot analysis in intact, hypophysectomized, and castrated rat POA, medial basal hypothalamus (MBH), cerebral cortex (CC), testis, and liver. Castration of hypophysectomy increased levels of the brain-specific 0.84 kb 5' porf-2 transcript in the POA, but did not affect levels of this transcript in the CC. There was a small decrease in the MBH following castration. Hypophysectomy also resulted in a fourfold increase in the 5' 1.1 kb testis-specific transcript. The affected transcripts are localized to the cytoplasm. A nontissue specific 3' transcript was also detected. Interestingly, this 0.6 kb transcript became non-detectable in all tissues examined following hypophysectomy. Porf-2 mRNA was also detected in human hypothalamus, testis, adrenal, placenta, and prostate with unique transcripts in each tissue examined . It has been shown elsewhere that porf-2 is a unique single copy gene in the rat genome. These data demonstrate that expression of the porf-2 gene is differentially regulated at the pretranslational level by intrinsic tissue-specific, as well as extrinsic pituitary and gonadal factors. The selected responses to reproductive hormonal status suggest that porf-2 may play a role in hypothalamic pituitary-gonadal interactions.

Expression of the preoptic regulatory factor-1 and -2 genes in rat testis. Developmental and hormonal regulation.

Hormone-responsive peptides play a vital role in development and regulation of testicular function. The preoptic regulatory factors, porf-1 and porf-2, were originally discovered in the rat brain, but are also expressed in the rat and human testis. In the brain expression is age-related, hormone-responsive, region- specific, and gender-related, suggesting that porf-1 and porf-2 are involved in gender-specific brain development and function. Tissue-specific porf-1 and porf-2 mRNAs are also found in the testis and hypophysectomy may alter testicular porf-2 expression. It was thus of interest to further examine porf-1 and porf-2 expression in the testis to evaluate their potential as hormone-responsive peptides that regulate testicular development and function. Testicular expression of both porf-1 and -2 was analyzed as a function of maturational stage, aging and hypophysectomy by the solution hybridization/nuclease protection assay, and cellular location determined by in situ hybridization histochemistry. Expression was quantitatively compared in normal male rats at 15, 30 and 60 d (n = 4) and at 2, 6, 12, and 24 mo of age (n = 5). During development porf-1 is expressed at a constant level at 15, 30 and 60 d, then declines significantly with advancing age; levels at 24 mo are only 20% of those seen at 2 mo (p < 0.05). In contrast, porf-2 expression is highest at 15 d of age and steadily declines at 30 and 60 d, plateaus in the mature adult (6 and 12 mo), then exhibits an additional significant decline in the aged 24 mo animals (6 vs 24 mo, p < 0.05). Hypophysectomy of young adult rats at day 42 results in increased testicular expression 12 d later of both porf-1 (p < 0.05) and porf-2(p < 0.005) compared to intact 54-d-old rats (n = 5). In situ hybridization histochemistry confirms that both porf-1 and porf-2 are expressed in the mature testis at 60 d of age. Porf-2 mRNA is localized to immature germ cells including spermatogonia and primary spermatocytes. Porf-1 mRNA is associated with mature sperm and at low levels in the Sertoli cell cytoplasm surrounding spermatocytes. These data suggest that porf-2 is a pituitary hormone-responsive factor in the developing testis and that both porf-1 and porf-2 have cell-type specific functions in the germ cell compartment of the mature testis

Sex-specific changes in preoptic regulatory factor-1 and preoptic regulatory factor-2 mRNA expression in the rat brain during development.

Preoptic regulatory factor-1 (Porf-1) and Preoptic regulatory factor-2 (Porf-2) are two novel peptide genes which are expressed in the central nervous system. Expression is modified by age and by hormones of the reproductive system. In this study nuclease protection assays were employed to investigate Porf-1 and Porf-2 mRNA expression in the cerebral cortex (CC), hippocampus (HIPP), preoptic area (POA) and medial basal hypothalamus (MBH) of male and female rats, aged 15, 30 and 60 days. Porf-1 and Porf-2 mRNA expression tended to decrease from 15 to 60 days, with two exceptions. Porf-2 in the hippocampus of female rats, and Porf-1 in the MBH of the male rats, were found instead to increase with age. There were distinctive sex differences inporf-1 andporf-2 gene expression. Consistently higher mRNA levels were measured for both genes in the POA of female rats at all ages examined, and this difference reached statistical significance for Porf-1 at the age of 60 days. In contrast, levels of Porf-2 mRNA were higher in MBH of male than female rat MBH at 15 days, and Porf-1 mRNA was substantially more abundant in male than in female rat MBH at 30 and 60 days of age. These results indicate that there is sexual dimorphism and regional specificity in the developmental expression of these genes.

Regional distinction in age-related changes of preoptic regulatory factor-1 and preoptic regulatory factor-2 mRNA expression in the rat brain.

Preoptic regulatory factor-1 (porf-1) and preoptic regulatory factor-2 (porf-2) are two novel neuropeptide genes expressed in the central nervous system and peripheral tissues. Other studies have shown that these genes may play a role in steroid-dependent brain development and functions. In this study, nuclease protection assays were employed to investigate Porf-1 and Porf-2 mRNA expression in male rat brains of different ages. The preoptic area (POA), cerebral cortex (CC), and hippocampus (HIPP) expressed both Porf-1 and Porf-2 mRNA, while only Porf-2 mRNA was detectable in the medial basal hypothalamus (MBH). Porf-1 mRNA in the POA was highest at the age of 2 months (young adult), decreased at the age of 6 months (mature adult), and remained low at the ages of 12 (middle aged) and 24 months (aged). Porf-1 mRNA in the CC was also the highest at the age of 2 months and decreased with age. However, there were no age-related changes for Porf-1 mRNA in the HIPP. Porf-2 mRNA in the HIPP was found to be low at the age of 2 months, increased at the ages of 6 and 12 months, and decreased at the age of 24 months. The effect of age on Porf-2 mRNA in the POA was similar to that seen for Porf-1, with the highest expression observed in the 2-month-old rats. There were no age-related Porf-2 mRNA changes in the MBH and CC. These results indicate differential regulation of expression of the porf-1 and porf-2 genes in the MBH, POA, HIPP, and CC. The possible roles of these two genes in maturation and aging of male rats are discussed.

Intrinsic and extrinsic modulators direct pretranslational expression of preoptic regulatory factor 1 (porf-1) messenger RNAs.

Genes of the diffuse neuroendocrine system are often widely expressed. We are studying a newly discovered peptide gene, preoptic regulatory factor 1 (porf-1). In the rat, porf-1 has been shown to be a unique, single-copy gene. Although its exact function remains unknown, porf-1 encodes a gonadotropin-releasing hormone (GnRH) related sequence and we have previously shown that this gene is transcribed in the rat in a tissue-specific manner in the preoptic area of the hypothalamus and in the testis. In this report, we extend the tissue distribution studies. Because of their potential expression of a GnRH related peptide, we also assess the effects of testicular and pituitary factors on porf-1 transcripts. RNA from the medial basal (MBH) and preoptic areas (POA) of the hypothalamus, cerebral cortex, testis, and liver from intact, castrated, and hypophysectomized male rats is compared by Northern blot analysis. Three basic tissue-specific patterns are observed in the intact animal, one common to the three brain areas examined, one for testis, and one for liver. Hypophysectomy results in a substantial increase in a unique 0.68-kb hypothalamic porf-1 transcript which is not detectable in either the intact or the castrated rat. It also results in increased levels of a 0.9-kb transcript in the POA and MBH. This is consistent with a negative feedback effect of the pituitary on porf-1 gene expression in the brain. In contrast, castration does not have a substantial effect on porf-1 hypothalamic transcripts, although a slight increase is seen in levels of the 0.9-kb species in the cerebral cortex. However, two different mature transcripts are identified with region-specific cRNA probes in the testis, suggesting that there may be cell-type-specific porf-1 gene expression in this tissue. These transcripts are not altered by hypophysectomy. We also examine human RNA from four reproductive hormone producing and hormone responsive tissues. There are three separate patterns of human porf-1 related transcripts which are different from those seen in the rat, one in placenta, one in adrenal, and one common to testis and prostate. We conclude that alternative RNA formation is a strategy being used by the diffuse neuroendocrine system to diversify expression of the porf-1 gene in response to intrinsic cellular and extrinsic hormonal signals.

Cloning of two hypothalamic cDNAs encoding tissue-specific transcripts in the preoptic area and testis.

Neuropeptides are central to the regulation of normal sexual development and reproduction. Two new hypothalamic cDNAs have been identified by Northern blot analysis and molecular cloning. Each potentially encodes a precursor for a unique GnRH-like decapeptide. Northern blot analysis reveals tissue-specific transcripts from each gene in the hypothalamus and testis. These preoptic area regulatory factor genes, PORF-1 and PORF-2, may thus encode members of a family of GnRH-related peptides which have been described in these tissues.

Gonadotropin-releasing hormone release by superfused hypothalami in response to norepinephrine.

We have been studying the release of gonadotropin-releasing hormone (GnRH) from adult male rat medial basal hypothalamus (MBH) utilizing a continuous flow superfusion system. This model system allows for direct application of modifying substances into the superfusion chambers and for continuous collection of effluent for radioimmunoassay of GnRH levels. Gonadotropin-releasing hormone is rapidly released in response to specific chemical stimuli. As demonstrated by others, pulses of KCl or prostaglandin E2 (PGE2) result in sharp peaks of GnRH release followed by rapid return to baseline. Forty millimolar KCl increases [GnRH] 3- to 4-fold, consistent with a membrane-associated secretory process for GnRH release. A 50-micrograms bolus of PGE2 results in a 2-fold rise in GnRH. Norepinephrine stimulates the release of GnRH in a log-linear dose-dependent manner in the range of 10(-9) to 10(-5) M norepinephrine (NE). At 10(-11) M, NE does not increase GnRH release above baseline, whereas at 10(-9) M NE GnRH release is increased 2-fold. The alpha-receptor blocker phentolamine significantly inhibits the NE-induced rise in GnRH. Propranolol, a beta-adrenergic receptor blocker, does not inhibit the GnRH response to NE. This study demonstrates a direct, dose-dependent, alpha-mediated stimulatory effect of NE on GnRH release from superfused male rat MBH, and establishes the potential of this system for the investigation of the GnRH response to other aminergic agents and their extraneural modifiers, including steroid hormones.

Proteinases in human polymorphonuclear leukocytes. Purification and characterization of an enzyme which cleaves denatured collagen and a synthetic peptide with a Gly-Ile sequence.

Polymorphonuclear leukocytes have been shown to contain proteolytic enzymes which are capable of degrading connective tissue proteins such as native collagen. In this study, proteolytic enzymes were extracted from human polymorphonuclear leukocytes and a neutral proteinase was extensively purified and characterized. The activity of this enzyme was monitored by degradation of denatured [ 3H ]proline-labeled type I collagen or by cleavage of a synthetic dinitrophenylated peptide with a Gly-Ile sequence. The enzyme was readily separated from leukocyte collagenase by concanavalin-A--Sepharose affinity chromatography and further purified by QAE-Sephadex ion-exchange chromatography and gel filtration on Sephacryl S-200. The purified enzyme had a molecular weight of approximately 105000, its pH optimum was about 7.8, and it was inhibited by Na2EDTA and dithiothreitol, but not by fetal calf serum. The enzyme degraded genetically distinct type I, II, III, IV and V collagens, when in a non-helical form, but not when in native triple-helical conformation. Dansyl-monitored end-group analyses, combined with digestion by carboxypeptidase A, indicated that the enzyme cleaved denaturated type I collagen at Gly-Xaa sequences, in which Xaa can be leucine, isoleucine, valine, phenylalanine, lysine, or methionine. Thus, the purified enzyme referred to here as Gly-Xaa proteinase, is a neutral proteinase, which may be of importance in inflammatory disease processes by degrading further collagen peptides which have been rendered non-helical as a result of collagenase cleavage.

Quantitative changes in the metabolism of 20alpha-hydroxy-4-pregnen-3-one by rat hypothalamus and pituitary during proestrus.

The in vitro conversion of 20alpha-hydroxy-4-pregnen-3-one (20alpha-DHP) by medial basal hypothalamus and anterior pituitary was investigated throughout the day of proestrus in the 4-day cyclic rat. Reverse isotopic dilution analysis was utilized to quantitate the substrate remaining and three metabolic products: 20alpha-hydroxy-5alpha-pregnan-3-one, 5alpha-pregnane-3alpha,20alpha-diol and progesterone. Serum levels of 20alpha-DHP, progesterone, LH and FSH were measured by radioimmunoassay. Conversion of 20alpha-DHP to its 5alpha-reduced metabolites (20alpha-hydroxy-5alpha-pregnan-3-one and 5alpha-pregnane-3alpha,20alpha-diol) by the pituitary was constant throughout proestrus except for a significant decrease at 1600 h, near the end of the critical period. Although 5alpha-reduction of 20alpha-DHP by the hypothalamus fluctuated, it was relatively high at 1600 h and was lowest at 1400 h. Small amounts of progesterone (less than2%) were formed but there was not variation with time. The decrease in pituitary enzymic activity coincided with the time when serum levels of LH, FSH and progesterone were increasing but not with later times when the elevated serum levels were maintained. Thus, there may be endogenous regulation of 5alpha-reductase and 3alpha-hydroxysteroid dehydrogenase activity in rat pituitary and perhaps hypothalamus on the afternoon of proestrus. The regulation and subsequent effects of quantitative changes in 5alpha-reduction of 20alpha-DHP by pituitary and hypothalamus remain to be elucidated.