Species differences in V1a receptor gene expression in monogamous and nonmonogamous voles: behavioral consequences

Arginine vasopressin modulates a number of species-typical social behaviors, including social memory in rats, scent marking and aggressive behavior in hamsters, and partner preference formation and paternal behavior in monogamous rodents. The distribution of V1a receptor binding sites in the brain varies greatly among species. Using in situ hybridization in 2 species of voles with strikingly different patterns of V1a binding sites and social behaviors, the authors demonstrate that differences in V1a receptor binding sites are due to species differences in regional V1a receptor gene expression. It is then demonstrated that the differences in receptor gene expression are associated with species differences in behavioral response to centrally administered vasopressin. Together, these data suggest that the phylogenetic plasticity of central neurohypophyseal peptide receptor expression may contribute to the evolution of species-typical social behaviors.

Species differences in V1a receptor gene expression in monogamous and nonmonogamous voles: behavioral consequences

Arginine vasopressin modulates a number of species-typical social behaviors, including social memory in rats, scent marking and aggressive behavior in hamsters, and partner preference formation and paternal behavior in monogamous rodents. The distribution of V1a receptor binding sites in the brain varies greatly among species. Using in situ hybridization in 2 species of voles with strikingly different patterns of V1a binding sites and social behaviors, the authors demonstrate that differences in V1a receptor binding sites are due to species differences in regional V1a receptor gene expression. It is then demonstrated that the differences in receptor gene expression are associated with species differences in behavioral response to centrally administered vasopressin. Together, these data suggest that the phylogenetic plasticity of central neurohypophyseal peptide receptor expression may contribute to the evolution of species-typical social behaviors.

Gene targeting approaches to neuroendocrinology: oxytocin, maternal behavior, and affiliation

Transgenic technology affords exciting new opportunities in the field of behavioral neuroendocrinology. We have extended our research into the behavioral function of oxytocin in maternal and social behavior using two transgenic approaches: (i) targeted deletion of the oxytocin gene in mice and (ii) augmented oxytocin receptor expression in the brain. Mice genetically deficient in oxytocin can mate, give birth, and display normal maternal behavior; however, milk ejection and certain aspects of social behavior are affected. Comparative studies of oxytocin receptors have led to the observation that species differences in social organization are associated with differences in receptor distribution. Specifically, monogamous prairie voles and nonmonogamous, asocial montane voles exhibit different patterns of OT receptor expression in the brain. Transgenic mice have been created with a reporter gene driven by the prairie vole oxytocin receptor gene promoter. Analysis of the expression pattern suggests that it should be possible to manipulate receptor expression in the vole brain in order to examine the effects of receptor distribution on behavior.

Species differences in vasopressin receptor binding are evident early in development: comparative anatomic studies in prairie and montane voles

Monogamous prairie voles (Microtus ochrogaster) and promiscuous montane voles (Microtus montanus) exhibit remarkable differences in the distribution of vasopressin (AVP) receptors in the adult brain. This difference in receptor distribution is associated with species differences in the behaviors, including pair bond formation and paternal care, found selectively in the monogamous vole. To investigate a potential mechanism for this species difference in AVP receptors, the present study examined the ontogeny of receptor binding in the two species to determine whether the adult maps arose from a shared pattern in development. By using 125I-linear-AVP, which is a selective high-affinity ligand for the V1a receptor, we found early appearance and transient expression of AVP receptor binding during postnatal development in both species. However, the ontogenetic patterns of regional AVP receptor binding were species specific. In the diagonal band, the bed nucleus of the stria terminalis, and the central nucleus of the amygdala, prairie voles had higher AVP receptor binding at birth than montane voles, and this difference persisted with little variation into adulthood. In these areas, therefore, species differences in AVP receptor binding appeared to be determined primarily by genetic or prenatal factors. In the lateral septum, both species had low levels of AVP receptor binding at birth. Thereafter, the binding increased rapidly in montane voles, but it remained unchanged in prairie voles. In the cingulate cortex, AVP receptor binding in prairie voles showed a peak in early development with a subsequent decline and reached the adult level at weaning, whereas the binding in montane voles remained unchanged into adulthood. A similar but opposite pattern was found in the frontoparietal cortex, in which AVP receptor binding showed an early peak in montane voles but did not change significantly in prairie voles. These results demonstrate that 1) species differences in regional AVP receptor binding are evident in the early postnatal period and, in several areas, may be determined by genetic or prenatal factors, and 2) AVP may target brain areas differently in infant and adult prairie and montane voles and, thus, could exert differential effects on the organization of the central nervous system in the two species of voles.

Oxytocin is required for nursing but is not essential for parturition or reproductive behavior

Oxytocin, a neurohypophyseal hormone, has been traditionally considered essential for mammalian reproduction. In addition to uterine contractions during labor and milk ejection during nursing, oxytocin has been implicated in anterior pituitary function, paracrine effects in the testis and ovary and the neural control of maternal and sexual behaviors. To determine the essential role(s) of oxytocin in mammalian reproductive function, mice deficient in oxytocin have been generated using embryonic stem cell technology. A deletion of exon 1 encoding the oxytocin peptide was generated in embryonic stem cells at a high frequency and was successfully transmitted in the germ line. Southern blot analysis of genomic DNA from homozygote offspring and in situ hybridization with an exonic probe 3' of the deletion failed to detect any oxytocin or neurophysin sequences, respectively, confirming that the mutation was a null mutation. Mice lacking oxytocin are both viable and fertile. Males do not have any reproductive behavioral or functional defects in the absence of oxytocin. Similarly, females lacking oxytocin have no obvious deficits in fertility or reproduction, including gestation and parturition. However, although oxytocin-deficient females demonstrate normal maternal behavior, all offspring die shortly after birth because of the dam's inability to nurse. Postpartum injections of oxytocin to the oxytocin deficient mothers restore milk ejection and rescue the offspring. Thus, despite the multiple reproductive activities that have been attributed to oxytocin, oxytocin plays an essential role only in milk ejection in the mouse.

Species differences in central oxytocin receptor gene expression: comparative analysis of promoter sequences

The distribution of oxytocin binding sites in the brain is highly variable among mammals. Using two species of microtine rodents (voles) with strikingly different patterns of oxytocin binding sites in the brain, we demonstrate that these differences are due to differences in region specific gene expression and not post-translational processing. The distribution of oxytocin receptor mRNA closely resembles the distribution of oxytocin receptor binding sites in both species. Analysis of the 5' flanking region of the oxytocin receptor gene from both species reveals few differences in potential regulatory elements which could explain the differences in gene expression. These data suggest that species differences in oxytocin receptor binding are due to species differences in: i) distant DNA sequences further upstream or downstream which may influence expression; ii) the distribution of regulatory proteins such as transcription factors in the brain or iii) epigenetic factors, such as prenatal and perinatal environment which may affect gene expression in the adult.

Occlusal vertical dimension in prosthodontics

Occlusal vertical dimension is important in all aspects of prosthodontics. Unfortunately, there is no scientific method of determining the correct occlusal vertical dimension. The amount of interocclusal rest space (IRS) is a rough guide since muscle tone, which determines the space, is variable. IRS varies greatly from one patient to the next. It will automatically be correct when the occlusal vertical dimension is correct. IRS should not be interfered with regardless of its size. Many techniques have been used for determining occlusal vertical dimension in dentulous and edentulous patients. Regardless of the technique, the occlusal vertical dimension must be determined carefully by the dentist for a successful prosthesis.

The Philippine cynomolgus monkey (Macaca fasicularis) provides a new nonhuman primate model of tuberculosis that resembles human disease

A nonhuman primate model of tuberculosis that closely resembles human disease is urgently needed. We have evaluated the Philippine cynomolgus monkey, Macaca fasicularis, as a model of TB. Cynomolgus monkeys challenged intratracheally with extremely high doses of Mycobacterium tuberculosis (10(5) or 10(4) CFU) developed an acute, rapidly progressive, highly fatal multilobar pneumonia. However, monkeys challenged with moderate or low doses of M. tuberculosis (</=10(3) CFU) developed a chronic, slowly progressive, localized form of pulmonary TB, akin to the disease in humans, that was frequently accompanied by such clinical syndromes as ocular tuberculosis, meningitis and tuberculous spondylitis. A significant proportion of monkeys challenged with 10(2) or 10(1) CFU contained the infection in a subclinical state. The Philippine cynomolgus monkey model is an excellent model of chronic TB and provides an opportunity to study subclinical and potentially latent disease in an animal model.

Reptilian sex steroid receptors: amplification, sequence and expression analysis

Sex steroid hormones secreted by the gonads play a central role in the reproduction of all vertebrates. In addition to direct effects on gametogenesis, sex steroid hormones are important in sexual development, brain organization, and sexual behavior. The actions of sex steroid hormones are mediated primarily by ligand-dependent transcription factors, or receptors which bind to specific sequences of the DNA and alter the transcription rates of nearby genes. We have used the polymerase chain reaction to amplify cDNA fragments of the estrogen receptor, progesterone receptor and androgen receptor from the unisexual whiptail lizard, Cnemidophorus uniparens. The lizard steroid hormone receptors share a high degree of sequence homology to the steroid hormone receptors of other vertebrates. Ribonuclease protection assays demonstrate that both estrogen receptor mRNA and progesterone receptor mRNA are increased in the oviduct during vitellogenesis and after estrogen treatment. This report demonstrates the utility of the polymerase chain reaction to generate species specific probes for comparative molecular studies and provides the first report of cDNA sequences for reptilian steroid hormone receptors.

Comparative neuroendocrinology of steroid receptor gene expression and regulation: Relationship to physiology and behavior

Great diversity exists among vertebrates in reproductive behaviors and the neuroendocrine mechanisms underlying these behaviors. Comparisons of species with different hormone-brain-behavior relationships reveal three factors which may explain species differences in endocrine physiology and behavior: (a) sensitivity to sex steroid hormones, (b) hormone-dependent regulation of sex steroid hormone receptor gene expression, and (c) neuroanatomical distribution of steroid receptor gene expression, especially in nonlimbic structures.

Species differences in estrogen receptor and progesterone receptor-mRNA expression in the brain of sexual and unisexual whiptail lizards

Circulating concentrations of gonadal steroid hormones and reproductive behavior in female vertebrates vary as a function of ovarian state. Steroids secreted by the ovary, specifically estrogen and progesterone, influence the expression of behaviors associated with reproduction by intracellular sex steroid receptors located in specific regions of the brain. Using in situ hybridization, we analyzed estrogen receptor and progesterone receptor messenger RNA expression in several brain regions of ovariectomized, vitellogenic, and postovulatory individuals from two species of whiptail lizards (Cnemidophorus uniparens and C. inornatus). Although these species are genetically very similar, they differ in two aspects of their reproductive biology: (i) the unisexual C. uniparens alternate between expressing female-typical and male-like pseudosexual behaviors while female C. inornatus normally express only female receptive behavior, and (ii) circulating estradiol concentrations in reproductively active female C. uniparens are approximately five-fold lower than in reproductively active female C. inornatus. We found that the regulation of sex steroid receptor gene expression was region specific, with receptor-mRNA expression being increased, unchanged, or decreased during vitellogenesis depending on the area. Furthermore, several species differences in the amount of sex steroid receptor-mRNA were found that may be relevant to the species differences in circulating estrogen concentrations and sexual behavior.

Species differences in behavioral and neural sensitivity to estrogen in whiptail lizards: correlation with hormone receptor messenger ribonucleic acid expression

Cnemidophorus uniparens is a unisexual species of whiptail lizard of hybrid origin whereas C. inornatus is a sexual species and the maternal ancestor of C. uniparens. Together they represent an excellent model system for investigating the evolution of hormone-brain-behavior relationships. Normal circulating estradiol (E) concentrations in C. uniparens are approximately 5-fold lower than those of female C. inornatus in a similar reproductive state. Experiments were performed to determine whether (i) C. uniparens is more sensitive to E, and (ii) whether the difference in sensitivity is correlated with differences in estrogen receptor (ER)-mRNA expression in the brain. Dose-response curves reveal that ovariectomized C. uniparens are more responsive than ovariectomized C. inornatus to exogenous estradiol 17 beta-benzoate (EB). EB is more effective in C. uniparens at inducing receptive behavior and progesterone receptor (PR) gene expression in the ventromedial nucleus of the hypothalamus (VMH). In situ hybridization analysis of ER-mRNA expression revealed no species differences in ER-mRNA content in the VMH of ovariectomized animals. Treatment of ovariectomized animals with EB resulted in a greater induction of ER-mRNA expression in the VMH of C. uniparens compared to C. inornatus. These results indicate that the differences in behavioral sensitivity to E lie in the estrogen target neurons in the brain region controlling receptive behavior, the VMH, and that the difference in sensitivity cannot be explained by species differences in the basal rate of ER gene expression.

Regulation of estrogen receptor and progesterone receptor messenger ribonucleic acid by estrogen in the brain of the whiptail lizard (Cnemidophorus uniparens)

Receptive behavior in females vertebrates is controlled by hormones, principally estrogen, secreted by the ovary. Estrogen influences behavior by interacting with a specific estrogen binding protein, or receptor, located in target cells in certain hypothalamic nuclei. To better understand the molecular mechanisms involved in the control of receptive behavior in whiptail lizards, we investigated the effects of exogenous estrogen on the regulation of estrogen receptor and progesterone receptor expression in several regions of the brains of Cnemidophorus uniparens. First we determined a dosage of 17 beta-estradiol 3-benzoate (0.5 micrograms) which reliably induced receptive behavior in ovariectomized C. uniparens. Then using in situ hybridization, we examined the effects of that dosage on the expression of estrogen receptor and progesterone receptor mRNA in the brain 24 h after injection. Estrogen treatment resulted in a significant up-regulation of estrogen receptor mRNA expression in the ventromedial nucleus of the hypothalamus and torus semicircularis, down-regulation of estrogen receptor mRNA expression in the lateral septum, and no change in the periventricular nuclei of the hypothalamus, the periventricular nucleus of the preoptic area, and the dorsal hypothalamus. The same dosage resulted in increased progesterone receptor mRNA expression in the ventromedial nucleus of the hypothalamus and the periventricular nucleus of the preoptic area; no significant changes in progesterone receptor mRNA expression were observed in the periventricular nuclei of the hypothalamus or the torus semicircularis, although the differences in progesterone receptor expression in the torus semicircularis approached statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone modulation of androgen-dependent sexual behavior in male rats

The present study examines the effects of physiological levels of progesterone (P) on copulatory behavior in sexually naive male rats. Two weeks after gonadectomy males were implanted with either empty Silastic capsules (BL) or Silastic capsules containing testosterone (T), P, or both (P+T). When tested with an estrous female, all of the gonadally intact males (intact) and none of the BL controls exhibited mounting/intromission behaviors. Mounting was observed in 75% of the T-alone males. More than half (64%) of the P-alone males and 100% P+T males exhibited mounting. In most cases, mounting was followed by intromission responses. Subsequently, intact and gonadectomized males received daily injections of the P antagonist RU486 along with hormone treatment. After receiving RU486, only 63% of the intact males and 71% of the T-alone males mounted successfully. The facilitatory effects of P on copulatory behavior were completely abolished by RU486 treatment. The present studies provide the first evidence in mammals suggesting that P-dependent mechanisms influence neurochemical pathways involved in copulation.

Reversion of malignant phenotype by 5-iodo-6-amino-1,2-benzopyrone a non-covalently binding ligand of poly(ADP-ribose) polymerase

A non-covalently binding inhibitory ligand of poly(ADP-ribose) polymerase, 5-iodo-6-amino-1,2-benzopyrone, when incubated at 5-600 microM external concentration with an E-ras-transformed tumorigenic cell line or with human prostatic carcinoma cells for 40 to 60 days converts both cancer cells to a non-tumorigenic phenotype that is characterized by drastic changes in cell morphology, absence of tumorigenicity in nude mice, and a high rate of aerobic glycolysis.

Cloning and in situ hybridization analysis of estrogen receptor, progesterone receptor, and androgen receptor expression in the brain of whiptail lizards (Cnemidophorus uniparens and C. inornatus)

Gonadal steroid hormones act upon specific areas of the vertebrate brain to affect the reproductive physiology and behavior of the animal. Steroid receptors are members of a superfamily of ligand-dependent transcription factors that mediate the effects of steroid hormones by modulating gene expression in the cells containing the receptors. The neuroanatomical distributions of steroid receptor-containing cells have been described for several species by using steroid autoradiography, immunocytochemistry, and more recently in situ hybridization. We have used the polymerase chain reaction to amplify and clone fragments of the estrogen receptor, progesterone receptor, and androgen receptor of whiptail lizards (genus Cnemidophorus). These clones were used to produce probes for use in in situ hybridization assays and to map the neuroanatomical distribution of all three sex steroid hormone receptors in the forebrains of unisexual (C. uniparens) and sexual (C. inornatus) species of whiptail lizards. The distribution of receptor-expressing cells reported here is in general agreement with previous reports in other species with receptor-containing cells concentrated in septal, amygdaloid, cortical, preoptic, and hypothalamic nuclei.

p53 gene mutation in female genital tract carcinosarcomas (malignant mixed müllerian tumors): a clinicopathologic study of 74 cases

Mutations of the p53 suppressor gene are involved in carcinogenesis by inactivating p53 protein (p53P), which is involved in normal cell growth control. Mutant p53P, detectable by immunohistochemistry due to longer half-life as compared to wild-type, is a marker for p53 gene mutation. Seventy-four female genital tract carcinosarcomas (FGTCSs) (41 of the heterologous type exhibiting 33 rhabdomyosarcomatous, 13 chondrosarcomatous, one osteosarcomatous, and one liposarcomatous component) were stained using two commercially available monoclonal antibodies: p53P, clone DO7 (p53P-DO7) and p53P, Ab-6 (p53P-P6). p53P-DO7 and p53P-P6 stained 33 and 36, respectively, of 56 endometrial, 8 of 11 ovarian, 2 of 5 cervical, and 2 of 2 fallopian tube carcinosarcomas. Considering all 74 FGTCSs, p53P-DO7 and p53P-P6 stained both the carcinomatous component (CC) and the sarcomatous component (SC) in 46% and 54%, the CC only in 9.5% and 8.1%, and the SC only in 5.4 and 2.7%, respectively. The two antibodies for p53P showed the following concordance for staining of FGTCSs (either CC or SC or both) (p53P-DO7/p53P-P6): +/+, 58%; +/-, 1.3%; -/+, 6.7%; -/-, 34%. p53P immunoreactivity was not associated with histological features or grade of the CC or SC. Clinical follow-up was available in 72 cases, which showed 48.5% and 70.8% of patients recurred or died of disease by 12 and 80 months, respectively. 20.8% of patients were disease-free after 19 to 307 months of follow-up (median, 62; mean, 92). The remaining 8.4% of patients were disease-free but had insufficient follow-up (< 1 year).(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone and sexual behavior in males

Previous investigations into the effects of progestins on copulatory behavior have suggested that progesterone inhibits the expression of androgen-dependent sexual behaviors in males. However, virtually all of those studies utilized pharmacological dosages of progesterone. Such experiments, although essential for understanding the behavioral effects of progesterone, yield little insight into the function of endogenous progesterone in masculine sexual responses. In this brief review, attention is focused on the role of physiological levels progesterone in copulatory behavior in male reptiles and mammals. Efforts are made to promote a reevaluation of the behavioral effects of progestins in males, similar to ongoing studies which are reexamining neural mechanisms involved in progestin-mediated reproductive behavior in the female.

Identification of an isoform of the estrogen receptor messenger RNA lacking exon four and present in the brain

An isoform of the estrogen receptor messenger RNA (ER-mRNA) was identified in RNA from the brain of lizards and rats. Poly(A)+ RNA from brain and uteri was reverse transcribed using gene-specific primer for the ER. The resulting complementary DNA was amplified in a polymerase chain reaction followed by cloning and sequencing of the amplified products. This isoform lacks exon four and is designated delta 4 ER-mRNA. Although several isoforms of the ER have been described from cancerous cells, to our knowledge, none has been identified previously in the brain. Furthermore, the delta 4 isoform is the only isoform detected in normal tissue. The delta 4 isoform appeared most abundant in RNA from brain tissue, whereas uterine RNA contained only trace amounts of the isoform. Apparently, tissue-specific alternative splicing accounts for these differences in abundance. Because exon four encodes a part of the steroid-binding domain, we predict that the corresponding protein encoded by the isoform will not bind estradiol and may therefore belong to a growing subclass of the steroid/thyroid/vitamin superfamily known as orphan receptors. We predict that the putative delta 4 protein may function as a ligand-independent transcription factor that acts on the same DNA response elements as the conventional ER. The abundance of this isoform in the brain relative to the uterus raises fundamental questions regarding the regulation of estrogen-responsive genes in different tissues.

Response of colostrum-deprived cynomolgus monkeys to intragastric challenge exposure with simian rotavirus strain SA11

The infectivity and pathogenic potential of a cell culture-adapted simian rotavirus was evaluated in colostrum-deprived newborn and infant cynomolgus macaques (Macaca fascicularis). Intragastric challenge exposure with the simian rotavirus strain SA11 on postpartum day 2 induced diarrhea in 5 of 5 colostrum-deprived newborn monkeys. Compared with sham-inoculated controls, 3 of the 5 inoculated monkeys also manifested reduced body weight gain during the initial 5 days after challenge exposure. Rotavirus was detected in feces of 3 challenge-exposed monkeys for up to 2 days after inoculation. Evaluation of antibody response after rotavirus inoculation was obscured by high but variable prechallenge-exposure serum titers of rotavirus-specific antibody. Preexisting serum titer of neutralizing antibody in newborn monkeys was not predictive of clinical response to inoculation with rotavirus SA11. Two 90-day-old infant monkeys with low serum neutralizing antibody titer did not have diarrhea, reduced weight gain, or antibody response after oral inoculation with rotavirus SA11. Results of these challenge-exposure studies in newborn cynomolgus monkeys were consistent with a heterologous host-rotavirus model and indicate that neonatal serum antibody of maternal origin may not be associated with resistance to rotavirus-induced disease.

The effects of progesterone on sexual behavior in male green anole lizards (Anolis carolinensis)

It is well known that androgen-dependent sexual behaviors in male mammals and birds are inhibited by exogenous progesterone (P). However, recent research on male whiptail lizards (Cnemidophorus inornatus) indicates that P can stimulate sexual and copulatory behavior. We report here both antiandrogenic and synandrogenic actions of P on sexual behavior in males of another reptile, the green anole lizard (Anolis carolinensis). Earlier reports on birds and mammals are reviewed and discussed in relation to a possible physiological role of P in influencing sexual behavior in male vertebrates.

Viral Ha-ras mediated mammary tumor progression

An immortal mammary epithelial cell line, Comma 1D, and primary cultures of mammary epithelial cells were used to examine the effects of vHa-ras on mammary tumor development. In culture, Comma 1D and primary cells were morphologically indistinguishable. Infection with a replication defective vHa-ras retroviral vector (psi ras) did not alter their in vitro phenotype. Uninfected Comma 1D cells implanted into gland-cleared mammary fat pads gave rise to dysplastic outgrowths, while implants of primary cells gave rise to normal gland structures. After psi ras infection, implants of Comma 1D cells progressed to adenocarcinomas and those of primary cells resulted in initiated dysplastic outgrowths. High level infection of either cell type with replication competent HaMSV (psi ras plus helper virus) resulted in in vitro transformation and undifferentiated in vivo tumors. Thus, in vivo analysis was necessary to detect the observed correlation between tumorigenic stage and level of infection. In this system, expression of vHa-ras was vital but not sufficient for mammary tumor initiation and progression, which resulted from an accumulation of events that did not need to occur in a specific order.