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D W Pfaff

Publications and source records attributed to D W Pfaff.

At least 253 records · Page 14Linked to original sources
PubMed1989

Expression and estrogen regulation of progesterone receptor mRNA in neurons of the mediobasal hypothalamus: an in situ hybridization study.

Diverse effects of steroid hormones on different tissues result from the tissue-specific regulation of target gene expression by steroid hormone receptors. These receptors belong to a family of transacting factors that regulate transcriptional activation of target genes by binding to DNA recognition sequences located in the 5'-flanking region of the target gene. In the brain, receptors for the gonadal steroid hormones estrogen (E) and progesterone (P) are present in discrete neuronal populations. These steroid hormone receptor-containing neurons mediate the effects of the gonadal steroids on a number of neural processes, including reproductive behavior. Using in situ hybridization we have found progesterone receptor (PR) mRNA-containing neurons present in specific hypothalamic nuclei and in the amygdala. E regulates PR mRNA levels in specific neuronal cell groups which express both ER and PR (in basomedial hypothalamus), but not in others (medial amygdala). The E-induced increase in P-responsive neurons in ventromedial hypothalamus can account for the permissive influence of E on P-facilitated reproductive behavior. This is the first demonstration that synthesis of a transcription factor (PR) can be related to a mammalian behavior.

Animals↗
PubMed1989

Tyrosine hydroxylase mRNA in the neurons of the tuberoinfundibular region and zona incerta examined after gonadal steroid hormone treatment.

The dopamine-producing neurons of the tuberoinfundibular region are known targets of estrogen and progesterone, and are of considerable neuroendocrine importance. To determine the anatomical distribution, and number of cells that contain tyrosine hydroxylase (TH) mRNA in the tuberoinfundibular region and other regions of the brain we carried out in situ hybridization on sections prepared from ovariectomized female rats given either oil vehicle, or estrogen, or estrogen plus progesterone. The intensity of label per cell was assessed to compare the relative amount of mRNA found per cell among TH-mRNA containing cells. [3H]cRNA probes to the rat TH sequence were used. Autoradiograms demonstrated the presence of TH-mRNA in the cytoplasm of cells in the arcuate and periventricular nuclei, zona incerta, substantia nigra, and the adrenal medulla. The number and anatomical distribution of cells that contained TH-mRNA was identical to the number and distribution of cells previously demonstrated by others to contain TH immunoreactivity. In the arcuate and periventricular nuclei, compared to treatment with estrogen alone, estrogen plus progesterone did lead to a statistically significant decrease in the number of TH mRNA-containing cells we could detect. No alteration in the mean number of grains per cell, among cells detected as containing TH-mRNA was found in any group. In contrast, these same hormone treatments had no effect on the number TH-mRNa producing cells we could detect in the zona incerta. Most of the cells in the zona incerta are found within the same tissue sections as arcuate/periventricular cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1988

Progesterone effects on sexual behavior and neuronal ultrastructure in female rats.

Treatment of female rats with a low dose of estradiol (5% estradiol in a 5 mm Silastic capsule) and progesterone (0.5 mg) increased the percentage of neurons in the ventromedial nucleus of the hypothalamus that contained stacks of rough endoplasmic reticulum, as compared with female rats receiving either estradiol alone or no treatment. Only females treated with both estradiol and progesterone displayed any sexual behavior, with these females responding at maximal levels. These results support the relationship between stacking of rough endoplasmic reticulum in ventromedial hypothalamic neurons and levels of sexual behavior in female rats, and provide evidence that progesterone can produce rapid changes in the morphology of hypothalamic neurons in estrogen-treated animals.

Animals↗
PubMed1988

Immunocytochemical localization of luteinizing hormone-releasing hormone (LHRH) in the brain and nervus terminalis of the adult and early neonatal gray short-tailed opossum (Monodelphis domestica).

Luteinizing hormone-releasing hormone (LHRH) was detected by immunocytochemical procedures in cells and fibers in the brain and in the nervus terminalis of the adult and neonatal gray, short-tailed opossum (Monodelphis domestica). As in several species of eutherian mammals, LHRH-immunoreactive cells and fibers were seen in the medial septal nuclei, nucleus, and tract of the diagonal band and olfactory tubercle. Surprisingly, few LHRH-immunoreactive cells were found in the hypothalamus or in the preoptic area in either the adult or neonate. LHRH-immunoreactive fibers were seen in these regions and were numerous in the median eminence. The nervus terminalis in the gray opossum showed several distinctive characteristics. Immunoreactive and nonreactive cells, in ganglia along the peripheral and intracranial course of this nerve, were accompanied by thick fascicles of LHRH fibers and frequently lay adjacent to blood vessels. No LHRH-immunoreactive branches of the nervus terminalis were found in contact with the vomeronasal nerves as they traversed the medial surfaces of the main olfactory bulbs en route to the accessory olfactory bulbs. The LHRH-immunoreactive fibers in the central roots of the nervus terminalis formed a compact bundle on either side of midline, which coursed obliquely from clusters of ganglion cells on the ventromedial surface of the olfactory bulbs into the septum. Traced through serial sagittal sections, LHRH-immunoreactive fibers, in continuity with those in the triangular nucleus of the septum, ran down and around the rostral face of the anterior commissure and fanned out into the medial preoptic area. As previously observed in the fetal guinea pig and rat, LHRH was detected in ganglion cells of the nervus terminalis of the newborn gray opossum preceding its detection in any other area of the brain.

Aging↗
PubMed1988

In situ hybridization analysis of osmotic stimulus-induced changes in ribosomal RNA in rat supraoptic nucleus.

A quantitative in situ hybridization analysis was used to investigate changes in levels of ribosomal RNA (rRNA) in neurons of the supraoptic nucleus (SON) of rats stimulated osmotically by giving 2% NaCl as drinking solution for 0 (control rats), 1, 4, and 14 days. The quantitation was autoradiographically accomplished by in situ hybridization with a nick-translated tritiated ribosomal DNA probe and with the use of computer-based image analysis system. The mean number of grains per neuron in the ventral SON was significantly increased: 1.8-fold for 1 day, 2.9-fold for 4 days, and 1.7-fold for 14 days of salt loading, whereas the mean number of grains per neuron in the dorsal SON was increased 1.3-fold for 1 day, 2.5-fold for 4 days, and 1.7-fold for 14 days. Kolmogorov-Smirnov analysis of frequency histograms of grains per neuron indicated that the amount of rRNA in neurons in the ventral and dorsal SON was significantly increased by osmotic stimulation. These increases were accompanied by increases in cell size. The subcellular location of hybridizable rRNA in magnocellular neurons was altered by osmotic stimulation. Following 1-14 days of salt-drinking, rRNAs appeared to be more unevenly distributed throughout the cytoplasm. These findings are consistent with the notion that hyperosmotic stimulation has a substantial effect on the expression of rRNA genes in neurons of both the ventral and dorsal SON.

Animals↗
PubMed1988

Estrogen-induced alterations in synaptic morphology in the midbrain central gray.

Axons of ventromedial hypothalamic (VMH) neurons have been previously shown to terminate in the midbrain central gray (MCG) (Chung et al. 1984, 1986). Since VMH synapses in this region may be involved in the mediation of estrogen-induced lordosis behavior, we examined the effect of estrogen on the morphology of synapses in the MCG. Ovariectomized adult female rats were given daily subcutaneous injections of estradiol benzoate (10 micrograms) or the vehicle control and after 20 days of injection, only the estrogen-treated rats showed the lordosis response. A quantitative analysis of MCG tissue from these animals demonstrates morphological changes in various synaptic parameters with estrogen treatment including: 1) an increase in the mean number of dense-cored vesicles and an increase in the number of terminals containing dense-cored vesicles, 2) an increase in the length of postsynaptic densities (PSDs), 3) an increase in the number of PSDs showing perforations, 4) an increase in the number of synapses, and 5) an increase in the number of synapses with positive synaptic curvature. No alterations in the number of subjunctional bodies were observed. The dense-cored vesicles may contain an estrogen-induced trophic factor which may function in maintaining the integrity of postsynaptic processes and cells in the MCG with which VMN endings contact (Chung et al. submitted) and/or which induces morphological changes in postsynaptic structures which facilitate the effects of estrogen on lordosis behavior.

Animals↗
PubMed1988

Vestibulospinal and reticulospinal interactions in the activation of back muscle EMG in the rat.

The effects of electrical stimulation of the lateral vestibular nucleus (LVN) and medullary reticular formation (RF) on electromyographic activity in axial muscles medial longissimus (ML) and lateral longissimus (LL) in the rat were studied. Long trains (150-500 ms) at 200-330 Hz and 20-100 microA were sufficient to activate ML and LL at latencies of 20-100 ms from the beginning of the train. Results of stimulation at 200-330 Hz to RF or LVN showed that muscle units were activated at a fixed latency from any effective pulse in the stimulus train. Using high frequency (1 kHz) trains of 3-6 pulses to LVN, EMG activity was detected at minimum latencies of 3.5-6 ms. When conduction times from the medulla to the spinal cord, and the spinal cord to the muscle are subtracted, this latency range is consistent with monosynaptic activation. In many cases, muscle units were recruited in order of size, with both RF and LVN stimulation. Combined stimulation of LVN and RF sites in n. gigantocellularis led to EMG activity in ML and LL at currents which were insufficient to evoke activity when presented singly. When stimulation of one site (300-400 ms train) was just sufficient to evoke a response, a shorter, overlapping train (100-150 ms) to the other site led to a higher rate of muscle activity that continued through the end of the long train, even after the short train had ended. In all cases, the effect of RF facilitating LVN was similar to the effect of LVN facilitating RF. The evidence for convergence between these two systems in the medulla and the spinal cord is discussed.

Action Potentials↗
PubMed1988

Cholinergic mechanisms of lordotic behavior in rats.

Cholinergic mechanisms of lordotic behavior were studied in hooded rats using behavioral techniques and autoradiographic analysis of the diffusion of [3H]N methyl scopolamine ([3H]NMS) applied to the hypothalamus. Bilateral cannulae were implanted chronically in the region of the ventromedial nuclei (VMN). A series of cholinergic drugs and estradiol (E2) were administered to each rat during successively induced periods of estrus. Robust inhibition of lordosis resulted from administration of atropine and scopolamine. Robust facilitation followed carbachol administration. Pirenzepine, hexamethonium, and tetraethylammonium did not inhibit lordosis. [3H]NMS, the last drug in the series to be administered, inhibited lordosis in two of three rats. Autoradiographic analysis of [3H]NMS diffusion in these rats revealed that radioactivity was confined entirely to the hypothalamus and appeared in the region of the VMN. In an additional experiment, the in vitro binding characteristics of [3H]NMS in the basomedial hypothalamus were examined. The VMN appeared lightly labeled and were surrounded by regions of darker labeling. We conclude that cholinergic drugs influence lordotic behavior when applied in crystalline form in the vicinity of the VMN of the female rat hypothalamus.

Acetylcholine↗
PubMed1988

Comparative effects of progesterone and alphaxalone on aggressive, reproductive and locomotor behaviors.

Progesterone can reduce aggressive behaviors in rodents under various experimental conditions, but it could be argued that this effect is due to the well known anesthetic/sedative properties of some steroids. We have tested this hypothesis by comparing the effects of progesterone and the anesthetic progestin, alphaxalone, on the aggressive, reproductive and locomotor behaviors of hamsters. Locomotion is used as a sensitive index of sedative/soporific effects. Progesterone reduced aggressive behavior without depressing the general locomotor activity of the animals, and it also facilitated feminine sexual behaviors in both sexes. Alphaxalone induced mild sedation in hamsters but this did not decrease their aggressive display. Alphaxalone did not facilitate feminine sexual behavior in either sex. We proposed that the inhibitory effect of progesterone on hamster aggressiveness is unlikely to follow from the hormone's sedative properties.

Aggression↗
PubMed1988

Effects of in vivo estradiol and progesterone on tritiated flunitrazepam binding in rat spinal cord.

Tritiated flunitrazepam binding was measured in autoradiograms of lumbar spinal cord from control ovariectomized female rats and from ovariectomized females treated with either estradiol-silastic implants or one subcutaneous injection of 500 micrograms progesterone 4-5 h before being killed or both estradiol and progesterone. Four areas of spinal cord were analyzed: the substantia gelatinosa, the region leading to and around the central canal, the remainder of the dorsal horn and the ventral horn. Specific flunitrazepam binding was greatest in the substantia gelatinosa and in the region around the central canal and was weakest in the ventral horn. Estradiol had no effect on flunitrazepam binding in the spinal cord despite estradiol concentrating cells in the substantia gelatinosa and around the central canal. In vivo progesterone enhanced flunitrazepam binding in the substantia gelatinosa while 10(-8) M progesterone in vitro was without effect. One day after spinal transection flunitrazepam binding in endocrine controls and estradiol-treated animals was unchanged but a progesterone injection 4-5 h before being killed had no effect on binding in the substantia gelatinosa.

Animals↗
PubMed1988

In situ hybridization demonstrates vasopressin gene transcription in hypothalamic neurons of crossbred hypertensive x diabetes insipidus rats.

In situ hybridization, Northern blotting, and solution hybridization assay were used to examine vasopressin-gene messenger ribonucleic acid (mRNA) transcripts in hypothalamic tissue from five strains of rats: Long-Evans, Wistar-Kyoto, and diabetes insipidus (Brattleboro) rats, spontaneously hypertensive-stroke-prone rats, and cross-bred diabetes insipidus x spontaneously hypertensive-stroke-prone rats. A 290 base-pair, single-stranded RNA probe, with 221 bases complementary to exon C of the vasopressin gene was synthesized by the SP6 transcription vector system. This probe labeled appropriate neurohypophysial hypothalamic neurons, as well as suprachiasmatic nucleus cells, in tissue samples from all five strains of rats. Confirming other recent hybridization results with diabetes insipidus rat brain tissue, diabetic animals were found to transcribe their mutated vasopressin gene. In addition, this investigation found that the cross-bred diabetic-hypertensive rat also synthesizes a vasopressin-gene messenger ribonucleic acid transcript. Quantitative analyses of solution and in situ hybridization results suggested the cross-bred diabetic-hypertensive rat exhibits a level of vasopressin-gene messenger ribonucleic acid similar to diabetes insipidus rats. This observation is consistent with previous data on the cross-bred diabetic-hypertensive rat which suggests they inherit the mutant vasopressin gene from Brattleboro rats.

Animals↗
PubMed1988

Modulatory actions of luteinizing hormone-releasing hormone on electrical activity of preoptic neurons in brain slices.

Single unit activity was recorded from 378 neurons, in two preoptic nuclei rich in luteinizing hormone-releasing hormone neurons, using in vitro brain tissue slices which were prepared form either ovariectomized or ovariectomized plus estradiol-treated rats. To test possible transmitter-like actions, agents were injected into the perfusion medium. Luteinizing hormone-releasing hormone excited 46%, inhibited 7%, and evoked biphasic responses in 2% of the 250 units tested. By comparison, two other peptides, thyrotropin-releasing hormone and cholecystokinin-octapeptide sulfated were exclusively excitatory, acting on 55 and 67% of the neurons, respectively. The response to thyrotropin-releasing hormone, cholecystokinin-octapeptide sulfated, and neurotransmitters were prompt, large, and consistent from trial to trial. In contrast, responses to luteinizing hormone-releasing hormone were usually delayed, small, and variable. Responses to the agents tested were not affected by in vivo estradiol treatment. Possible modulatory actions of luteinizing hormone-releasing hormone were tested by comparing the responses of single neurons to norepinephrine and serotonin before and after an application of luteinizing hormone-releasing hormone. In 39 and 20% of the 119 neurons tested, the norepinephrine responses were potentiated and attenuated, respectively, by luteinizing hormone-releasing hormone. In 46 serotonin-responsive neurons, 28% were potentiated and 22% attenuated. These neuromodulatory actions of luteinizing hormone-releasing hormone were specific in affecting only certain responses of certain neurons, and they were not duplicated on the same neurons by thyrotropin-releasing hormone. It appears that luteinizing hormone-releasing hormone may be a neuromodulator in the preoptic area.

Action Potentials↗
PubMed1988

In situ hybridization histochemistry with oxytocin synthetic oligonucleotide: strategy for making the probe and its application.

A 25 mer synthetic oligonucleotide, complementary to a specific region of the oxytocin-neurophysin preprohormone messenger RNA (mRNA), was designed for its application to in situ hybridization histochemistry. The probe was 3'-end labeled with [3H] deoxycytidine triphosphate (dCTP) by using terminal deoxynucleotidyl transferase, and hybridization of the labeled probe to the mRNA in the rat hypothalamus was visualized autoradiographically. Hybridization products were specifically localized in the dorsal part of the supraoptic nucleus and the peripheral part of the paraventricular nucleus. Not only is the oligomer designed useful for distinguishing oxytocin from vasopressin gene expressing neurons, but also it is proving useful for studies of estrogen-progesterone effects on neurons in the paraventricular nucleus. Thus, these results indicate that in situ hybridization histochemistry with synthetic oligonucleotide can be a valuable approach to measuring gene expression in hypothalamic neuroendocrine cells.

Animals↗
PubMed1988

Transmitter and peptide actions on hypothalamic neurons in vitro: implications for lordosis.

This article summarizes a series of studies using brain tissue slices of rats to record single-unit activity from the hypothalamic ventromedial nucleus (VMN) and preoptic area (POA), both of which are crucial for the regulation of the estrogen-dependent feminine mating behavior, lordosis. In these studies the actions of acetylcholine (ACh), serotonin (5HT), norepinephrine (NE), luteinizing hormone-releasing hormone (LHRH), arginine-vasopressin (AVP), and oxytocin (OXY) on neuronal activity were investigated. The results show that these agents could evoke either direct responses or neuromodulatory changes from VMN or POA cells in vitro. Comparison of the net neuronal actions of each of these agents with their effects on lordosis behavior revealed interesting correlations. All the excitatory agents, i.e., ACh, AVP, OXY, and LHRH, have been indicated by intracerebral application studies to be facilitatory on lordosis. The inhibitory agent, 5HT, could inhibit lordosis, when applied to the VMN and its vicinity. Such correlations indicate that these transmitters and peptides can facilitate or inhibit lordosis by increasing or decreasing, respectively, the frequency of action potentials in the types of hypothalamic neurons recorded here.

Action Potentials↗
PubMed1988

Hypothalamic serotonin lesions unmask hormone responsiveness of lordosis behavior in adult male rats.

Hypothalamic lesions of serotoninergic afferents following bilateral stereotoxic injections of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into the region of the ventromedial hypothalamus enhanced the effects of hormonally induced lordosis responding in both male and female rats. However, similarities and differences in the enhanced responsiveness to ovarian hormones were observed between the sexes. Compared with sham-lesioned controls, lesioned males displayed elevated lordosis responding to estradiol (E) priming alone, as well as to priming with E followed by progresterone (P). On the other hand, lesioned females displayed elevated lordosis in response to E priming alone, but were not different from controls in a synergistic facilitation of lordosis by P after E priming. With respect to receptivity, neither lesioned nor control males displayed ear-wiggling and hop-darting in response to E + P, whereas both lesioned and control females were proceptive following this treatment. Therefore, hypothalamic lesions following 5,7-DHT increase lordosis, but fail to unmask in males the responsiveness to E + P priming proceptive behaviours by females. Further, the levels of lordosis responding displayed by lesioned males are lower than those of either lesioned or control females after E + P priming, as well as those of lesioned females after E priming alone, thus indicating that other inhibitory mechanisms continue to operate in the lesioned males.

Animals↗
PubMed1988

Quantitative assessment of early and discontinuous estradiol-induced effects on ventromedial hypothalamic and preoptic area proteins in female rat brain.

In this study, changes in individual proteins in the ventromedial hypothalamus (VMN) and the preoptic area (POA) of the female rat brain were quantitatively assessed following either a short treatment (2 h) or a discontinuous schedule of estradiol. Ovariectomized (OVX) rats were implanted with estradiol capsules or sham-implanted for the appropriate paradigm and sacrificed by decapitation. Punches of brain tissue containing the VMN and POA were incubated with 35S-methionine and 35S-cysteine, and the labeled proteins separated by two-dimensional gel electrophoresis. Estradiol-induced changes were quantitatively assessed by computerized optical densitometry and subjected to a normalization procedure between pairs of estradiol-treated and OVX control gels. A number of proteins within the VMN and POA were found to be positively or negatively affected in labeling after either hormone administration paradigm. In both brain regions, the population of proteins affected in labeling after 2 h of estradiol treatment were markedly different from those affected after the discontinuous hormone paradigm. Comparison of the VMN and POA also indicated that the populations of proteins affected in labeling by either hormone treatment paradigm were different, with there being only 3 proteins (from a total of 39) affected in the same direction and 2 affected in the opposite direction by the hormone in both regions. These findings lend support to the hypothesis that administration of estradiol results in a molecular cascade of events within brain regions involved in the control of reproductive behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Estrogen increases proenkephalin messenger ribonucleic acid levels in the ventromedial hypothalamus of the rat.

The effects of estrogen on proenkephalin (PE) gene expression were measured in neurons of the ventromedial hypothalamus. Slot blot hybridization analysis indicates that the levels of PE mRNA in the ventromedial hypothalamus of ovariectomized rats increase 3.1-fold after 2 weeks of estrogen replacement. In situ hybridization reveals that the estrogen-inducible enkephalinergic neurons are located in the ventrolateral aspect of the ventromedial nucleus, a subnucleus known to contain many estrogen-concentrating neurons. The increase in PE mRNA levels is due to both a 63% increase in the number of detectable PE mRNA-containing neurons and a 2.0-fold increase in the levels of PE mRNA per enkephalinergic neuron (1.63 x 2.0 = 3.3-fold overall induction). This estrogen-regulated enkephalinergic cell group may represent part of the neural network mediating estrogen's effects on reproductive behavior and/or other neuroendocrine processes.

Animals↗