The effects of sex and neonatal stress on pituitary adenylate cyclase-activating peptide expression.

NEW FINDINGS: What is the central question of this study? Does sex or neonatal stress affect the expression of pituitary adenylate cyclase-activating peptide or its receptors? What is the main finding and its importance? Neonatal-maternal separation stress has little long-lasting effect on the expression of pituitary adenylate cyclase-activating peptide or its receptors, but sex differences exist in these genes between males and females at baseline. Sex differences in classic stress hormones have been studied in depth, but pituitary adenylate cyclase-activating peptide (PACAP), recently identified as playing a critical role in the stress axes, has not. Here we studied whether baseline levels of PACAP differ between sexes in various stress-related tissues and whether neonatal-maternal separation stress has a sex-dependent effect on PACAP gene expression in stress pathways. Using quantitative RT-PCR, we found sex differences in PACAP and PACAP receptor gene expression in several respiratory and/or stress-related tissues, while neonatal-maternal separation stress did little to affect PACAP signalling in adult animals. We propose that sex differences in PACAP expression are likely to contribute to differences between males and females in responses to stress.

Efficient cross polarized wave generation for compact, energy-scalable, ultrashort laser sources.

The generation of high contrast and ultrashort laser pulses via a compact and energy-scalable cross polarized wave filter is presented. The setup incorporates a waveguide spatial filter into a single crystal XPW configuration, enabling high energy and high intensity transmission, efficient contrast enhancement and pulse shortening at the multi-mJ level. Excellent XPW conversion of up to 33% (global efficiency: 20%, intensity transmission: 40%) led to an output energy of 650 µJ for an input of 3.3 mJ. Additionally, efficient conversion under specific input phase conditions, allowed pulse shortening from 25 fs to 9.6 fs, indicating the prospective application of this setup as a high energy, ultrabroad laser source.

A laser-plasma accelerator producing monoenergetic electron beams.

Particle accelerators are used in a wide variety of fields, ranging from medicine and biology to high-energy physics. The accelerating fields in conventional accelerators are limited to a few tens of MeV m(-1), owing to material breakdown at the walls of the structure. Thus, the production of energetic particle beams currently requires large-scale accelerators and expensive infrastructures. Laser-plasma accelerators have been proposed as a next generation of compact accelerators because of the huge electric fields they can sustain (>100 GeV m(-1)). However, it has been difficult to use them efficiently for applications because they have produced poor-quality particle beams with large energy spreads, owing to a randomization of electrons in phase space. Here we demonstrate that this randomization can be suppressed and that the quality of the electron beams can be dramatically enhanced. Within a length of 3 mm, the laser drives a plasma bubble that traps and accelerates plasma electrons. The resulting electron beam is extremely collimated and quasi-monoenergetic, with a high charge of 0.5 nC at 170 MeV.

A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam.

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays--in structural biology, for example--anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should fulfil these requirements but will be limited in number; the pressure on beamtime is therefore likely to be considerable. Laser-driven soft X-ray sources offer a comparatively inexpensive and widely available alternative, but have encountered practical bottlenecks in the quest for high intensities. Here we establish and characterize a soft X-ray laser chain that shows how these bottlenecks can in principle be overcome. By combining the high optical quality available from high-harmonic laser sources (as a seed beam) with a highly energetic soft X-ray laser plasma amplifier, we produce a tabletop soft X-ray femtosecond laser operating at 10 Hz and exhibiting full saturation, high energy, high coherence and full polarization. This technique should be readily applicable on all existing laser-driven soft X-ray facilities.

Coherence-based transverse measurement of synchrotron x-ray radiation from relativistic laser-plasma interaction and laser-accelerated electrons.

We observe Fresnel edge diffraction of the x-ray beam generated by the relativistic interaction of a high-intensity laser pulse with He gas. The observed diffraction at center energy 4.5 keV agrees with Gaussian incoherent source profile of full-width-half-maximum (FWHM) < 8 microm. Analysis indicates this corresponds to an upper limit on the transverse profile of laser-accelerated electrons within the plasma in agreement with three-dimensional, particle-in-cell results (FWHM = 4 microm).

Sympathetic innervation of the upper and lower regions of the uterus and cervix in the rat have different origins and routes.

The origins and routes of the postganglionic sympathetic nerve supply to the upper and lower uterus and to the cervix were investigated in the rat by using denervation procedures combined with immunohistochemistry and retrograde tracing. The sympathetic nerve fibers of the upper part of the uterus arise from the ovarian plexus nerve. They mainly originate (90%) from neurons of the suprarenal ganglia (SRG) and of the T10 to L3 ganglia of the paravertebral sympathetic chain. Fluoro-Gold injections into different regions of the upper uterus showed that the SRG neurons mainly provide innervation to the tubal extremity (52%) rather than to the uterine portion below this area (26%). Very few neurons of the celiac ganglion or the aorticorenal ganglia participated in this innervation. Most of the sympathetic innervation of the lower uterus and the cervix (90%) originates from neurons of the paravertebral ganglia T13 to S2, principally at the L2-L4 levels. By using immunocytochemistry, we show that very few tyrosine hydroxylase-positive neurons of the pelvic plexus project to these areas, where they represent only 3% of the sympathetic nerve supply. Again, very few neurons of the inferior mesenteric ganglion (IMG) supply the lower uterus and the cervix. The comparison between retrograde tracing experiments in intact animals and after the removal of the IMG shows that very few sympathetic postganglionic axons from the paravertebral chain pass through the IMG to reach the lower uterus and the cervix. In contrast, these axons mainly project to splanchnic nerves bypassing the IMG to connect with the hypogastric nerves. In addition, some axons supplying the lower uterus follow the superior vesical arteries and then reach the organ. Taken together, these results show that the upper region of the uterus receives a sympathetic innervation that is different in origin and route from that of the lower uterus and the cervix. Such a marked region-specific innervation suggests that nerve control of the myometrial activity may be functionally different between the oviduct and the cervical ends of the uterus.

Localization of androgen receptor in nitric oxide synthase- and vasoactive intestinal peptide-containing neurons of the major pelvic ganglion innervating the rat penis.

Neurons of the rat major pelvic ganglia provide innervation to the pelvic organs and external genitalia. In these ganglia, a subpopulation of neurons containing either nitric oxide synthase or vasoactive intestinal peptide or both molecules, is involved in penile erection. The androgen dependence of penile erection is a well established fact. After castration, decreased testosterone levels have been documented to produce erectile dysfunction possibly resulting from functional alterations in major pelvic ganglion neurons. It was therefore of interest to investigate the presence of androgen receptor within these ganglionic neurons. By using immunohistochemistry and a retrograde labeling technique we have demonstrated that the androgen receptor is present in about 40% of neurons of the major pelvic ganglion innervating the corpora cavernosa of the rat penis. In the major pelvic ganglion, 87% and 81% of the neurons labeled with the fluorescent dye Fast Blue from the penis contained nitric oxide synthase-like immunoreactivity and vasoactive intestinal peptide-like immunoreactivity, respectively. Androgen receptor was present in 20% of neurons containing vasoactive intestinal peptide-like immunoreactivity and about 40% of those containing nitric oxide synthase-like immunoreactivity. These results suggest that androgens, which are known to modulate penile erection, may regulate nitric oxide synthase and vasoactive intestinal peptide within the major pelvic ganglion via a direct interaction with ganglionic neurons.

Autonomic control of penile erection: modulation by testosterone in the rat.

The role of testosterone on peripheral autonomic control of penile erection was studied in rats. Erectile response to cavernous nerve stimulation was measured by intracavernous pressure associated with arterial blood pressure monitoring in anesthetized adult males. Comparison was performed between control (Co), castrated (Ox) and castrated, testosterone-replaced (OxT) rats. Ox rats exhibited smaller erectile responses. Testosterone replacement restored these responses in OxT rats. To identify the peripheral target of testosterone, postganglionic neurons of the major pelvic ganglion, innervating the corpora cavernosa through the cavernous nerves, were separated from the spinal cord by preganglionic axotomy of the pelvic nerves in three other groups of rats (PNx). Erectile response was unchanged in PNx rats, decreased in OxPNx more than in Ox rats, and restored by testosterone replacement (OxPNxT rats). We ruled out the participation of a somatic component in the erectile response in this model as there was no difference between curarized and Co rats. We infer that testosterone enhances the erectile response of cavernous nerve stimulation, acting peripherally to the spinal cord. Arguments are provided that the sites of action for testosterone or its metabolites are situated on neurons rather than on penile erectile tissue. Proerectile postganglionic parasympathetic neurons seem to be the exact target for gonadal steroids.

Influence of estrous cycle on vaginocervical sensitivity: a fos-immunohistochemical study of lumbosacral spinal cord.

Expression of c-fos in L(5)-S(1) spinal segments in response to mechanical vaginocervical stimulation was investigated in both cycling and ovariectomized females. The aim of this paper was to verify the influence of estrous cycle on females genital tract sensitivity using immunodetection of a neural activity endogenous marker. The results indicate that lumbosacral spinal Fos-labeling was highly increased in vaginocervical stimulated rats relative to control, and labeled neurons were present more intensively in the dorsal horn in comparison to other spinal areas. Significant differences in Fos-labeling were observed according to the estrous cycle stage at which the stimulation was applied. In estrous females, the response was greater than that obtained at diestrous and much greater than the response of proestrous females. The spinal Fos-labeling of ovariectomized females is equivalent to that of diestrous females. These results give evidence that the vaginocervical induced expression of c-fos is modulated by cyclic changes in circulating sex hormones, whereas results observed in ovariectomized females indicate the likely involvement of other mechanisms independent of ovarian hormones.

Small intensely fluorescent cells of the rat paracervical ganglion synthesize adrenaline, receive afferent innervation from postganglionic cholinergic neurones, and contain muscarinic receptors.

In the paracervical ganglion (PCG) of the rat, double-labelling immunofluorescence for catecholamine-synthesizing enzymes and HPLC measurement of catecholamine contents were first performed to evaluate whether intraganglionic small intensely fluorescent (SIF) cells are capable of synthesizing adrenaline. Immunolabelling for tyrosine hydroxylase (TH), dopamine beta-hydroxylase and phenylethanolamine-N-methyl transferase (PNMT) occurred in all SIF cells of the PCG, thus demonstrating the presence of all the enzymes required for adrenaline biosynthesis. Adrenaline levels were undetectable in the PCG but to test the hypothesis that PNMT is active in SIF cells, catecholamines were measured in ganglia of rats pretreated with pargyline, an inhibitor of the monoamine oxidase, the major enzyme involved in the catecholamine degradation. Pargyline treatment increased adrenaline levels in the PCG, thus demonstrating that SIF cells are capable of adrenaline synthesis. The undetectable levels of adrenaline in the PCG of untreated rats suggested a slow rate of biosynthesis of adrenaline in the ganglion. Furthermore, the use of double-labelling showed that SIF cells of the PCG were stained for muscarinic receptors and were approached by varicose ChAT-immunoreactive nerve fibres. Nerve fibres immunoreactive for ChAT were also observed associated with nerve cell bodies of ganglion neurones. Following deafferentation of the PCG, the ChAT-immunoreactive nerve fibres surrounding nerve cell bodies totally disappeared indicating their preganglionic origin, while those associated with SIF cells did not degenerate, which demonstrate that they derived from intraganglionic cholinergic neurones. Taken together, the results show that adrenaline may be a transmitter for SIF cells in the PCG and suggest that cholinergic neurones of the parasympathetic division of the PCG can modulate the SIF cell activity through the activation of muscarinic receptors.

Physiological evidence of neural pathways involved in reflexogenic penile erection in the rat.

To elucidate neural pathways responsible for the occurrence of reflexogenic erections, the response of the corpus cavernosum to electrical stimulation of the dorsal nerve of the penis (DNP) was measured in anesthetized, acutely spinalized rats. Stimulation elicited a dramatic increase in intracavernous pressure (ICP). ICP response was decreased by 70% after sectioning the pelvic nerve homolaterally to the stimulated DNP and abolished after bilateral section. ICP response was not impaired by curarization, but its latency was lengthened. Thus we physiologically evidenced a reflex loop independent from supraspinal centers between DNP and the pelvic nerve supporting penile reflexogenic erection.

Dynamics of Raman instabilities using chirped laser pulses.

Time resolved measurements of the growth of Raman instabilities were performed using a picosecond chirped laser pulse. It was observed experimentally that for a short laser pulse (<10 ps), forward and 30 degrees Raman scattering occur at the back of the pulse. The growth of the instabilities was found to be independent of the sign of the chirp. In addition, a simple temporal model was developed and shows good agreement with the experimental results. This model also indicates that the plasma wave driven by forward Raman scattering is severely damped in the case of pulses longer than a few picoseconds. Damping by the modulational instability is compatible with the experimental results.

High-energy electron beam production by femtosecond laser interactions with exploding-foil plasmas.

The interaction of an ultraintense, 30-fs laser pulse with a preformed plasma was investigated as a method of producing a beam of high-energy electrons. We used thin foil targets that are exploded by the laser amplified spontaneous emission preceding the main pulse. Optical diagnostics show that the main pulse interacts with a plasma whose density is well below the critical density. By varying the foil thickness, we were able to obtain a substantial emission of electrons in a narrow cone along the laser direction with a typical energy well above the laser ponderomotive potential. These results are explained in terms of wake-field acceleration.

High-resolution gamma-ray radiography produced by a laser-plasma driven electron source.

An electron beam from a laser-plasma accelerator is converted into a gamma-ray source using bremsstrahlung radiation in a dense material. The gamma-ray beam has a pointlike source size because it is generated by a high quality electron beam with a small source size and a low divergence. Using this gamma-ray source, the radiography of complex and dense objects with submillimeter resolution is performed. It is the first evidence of a gamma-ray source size of a few hundreds micrometers produced with laser-driven accelerators. This size is consistent with results from Monte Carlo simulations.

Observation of laser-pulse shortening in nonlinear plasma waves.

We have measured the temporal shortening of an ultraintense laser pulse interacting with an underdense plasma. When interacting with strongly nonlinear plasma waves, the laser pulse is shortened from 38 +/- 2 fs to the 10-14 fs level, with a 20% energy efficiency. The laser ponderomotive force excites a wakefield, which, along with relativistic self-phase modulation, broadens the laser spectrum and subsequently compresses the pulse. This mechanism is confirmed by 3D particle in cell simulations.

Absolute time-resolved x-ray laser gain measurement.

We present the first direct measurement of the time evolution of the gain of a soft x-ray laser amplifier. The measurement is based on the injection of a seed pulse, obtained by high-order harmonic generation, into an x-ray laser medium. Strong amplification occurs when the seed pulse is synchronized with the gain period. By precisely varying the delay between the x-ray laser plasma creation and the seed pulse injection, the actual temporal evolution of the soft x-ray amplifier gain is obtained with a subpicosecond resolution.

Plasma ion evolution in the wake of a high-intensity ultrashort laser pulse.

Experimental investigations of the late-time ion structures formed in the wake of an ultrashort, intense laser pulse propagating in a tenuous plasma have been performed using the proton imaging technique. The pattern found in the wake of the laser pulse shows unexpectedly regular modulations inside a long, finite width channel. On the basis of extensive particle in cell simulations of the plasma evolution in the wake of the pulse, we interpret this pattern as due to ion modulations developed during a two-stream instability excited by the return electric current generated by the wakefield.

Electrophysiological study of vagal afferent and efferent units in conscious sheep.

Crossed-nerve anastomoses were performed to record activity of vagal efferents and afferents during regurgitation and eructation in conscious sheep. Following anastomoses of the central end of a vagus nerve to the peripheral end of a phrenic nerve, discharges in units of the diaphragm reinnervated by vagal efferent neurones were associated with contractions of the caudal oesophagus and of the rumen. During regurgitation in the course of rumination, discharges in oesophageal efferents consisted of a characteristic pattern of two bursts in a constant association with the additional phase of the reticular contraction and the more forceful inspiratory effort. Discharges in two types of units bore a temporal relation with the motor gastric cycles. Early units are interpreted as innervating pillars of the rumen and late units its dorsal wall. Regular patterns of discharge were recorded during successive A sequences of rumen contractions. In contrast, there was a variability of pattern of activity of efferents during B sequences: a constant time relationship was not observed between discharges of both types of units. During B sequences accompanied by eructation, the most characteristic pattern in gastric and oesophageal units had the following features: the impulses in the early units increased in frequency, outlasted the discharge in the late units by 1 s and ended when a brief discharge was recorded in an oesophageal unit at the time of eructation. It is suggested from the patterns of discharge observed in both gastric and oesophageal efferents that the orderly sequence which achieves regurgitation and eructation results from the central co-ordination of efferent output. Following anastomoses of the central root of the nodose ganglion to the peripheral end of the accessory nerve, discharges in units of the mastoido-humeral muscle reinnervated by vagal afferent axons were associated with contractions of the oesophagus and movements of the larynx during swallowing and regurgitation. Discharges in oesophageal afferents coming from the caudal oesophagus were coincident with discharges observed in the vagal efferent fibres innervating this part of the oesophagus. Afferents from the pharynx and the larynx were active at the same time as the nasopharynx and the glottis were demonstrated to be closed. Thus the major characteristics of the afferents the traffic of which has been recorded in cross-sutured sheep in the course of rumination is that their discharges are occurring at the same time as motor events are developing.(ABSTRACT TRUNCATED AT 400 WORDS)

Reinnervation of striated muscle by peripheral vagal fibres cut above or below the nodose ganglion in the cat and rabbit.

In cats and rabbits, the peripheral stump of the vagus nerve cut above the nodose ganglion (supranodose anastomoses: s.n.) or below this ganglion (infranodose anastomoses: i.n.) was either sutured with epineurial sutures to the peripheral stump of the branch of the spinal accessory motor nerve innervating the sterno-cleido-mastoid (s.c.m.) muscle, or directly implanted in this muscle after resection of its motor nerve. After about six months, reinnervation of this muscle by vagal fibres was studied. By electromyographic recording during electrical stimulation of the cervical vagus nerve, it was shown that the vagal reinnervation of the s.c.m. muscle was established in 65% of the cats studied (57% s.n., 69% i.n.) and 33% of rabbits (37% s.n. and 31% i.n.). The average number of distinct potentials recorded in the reinnervated muscle, following vagal stimulation, was twenty-two in s.n. cats, thirteen in i.n. cats, eleven in s.n. rabbits and twelve in i.n. rabbits. Recorded potentials were monophasic (8%), biphasic (22.5%), triphasic (11.5%) or polyphasic (58%). These potentials were abolished by curare and alpha-bungarotoxin. The use of retrograde axonal transport of horseradish peroxidase showed labelled cells in the nodose ganglion, the cervical vagus and cranial thoracic vagus, and in the stellate ganglia. It is concluded that cholinergic vagal afferents reinnervated the s.c.m. muscle. Involvement of the sympathetic system is discussed.