Expression Of Fos Immunoreactivity Research Articles

Effects of pelvic, pudendal, or hypogastric nerve cuts on Fos induction in the rat brain following vaginocervical stimulation

In the female rat, genitosensory input is conveyed to the central nervous system predominantly through the pelvic, pudendal, and hypogastric nerves. The present study examined the relative contribution of those three nerves in the expression of Fos immunoreactivity within brain regions previously shown to be activated by vaginocervical stimulation (VCS). Bilateral transection of those nerves, or sham neurectomy, was conducted in separate groups of ovariectomized, sexually-experienced females. After recovery, females were primed with estrogen and progesterone and given either 50 manual VCSs with a lubricated glass rod over the course of 1 h. VCS increased the number of neurons expressing Fos immunoreactivity in the medial preoptic area, lateral septum, bed nucleus of the stria terminalis, ventromedial hypothalamus, and medial amygdala of sham neurectomized females. Transection of the pelvic nerve reduced Fos immunoreactivity in the medial preoptic area, bed nucleus of the stria terminalis, ventromedial hypothalamus, and medial amygdala, whereas transection of the pudendal nerve had no effect. In contrast, transection of the hypogastric nerve increased Fos immunoreactivity in the medial preoptic area and lateral septum, whereas transaction of the pelvic nerve increased Fos immunoreactivity in the lateral septum, following VCS. All females given VCS, except those with pelvic neurectomy, displayed a characteristic immobility during each application. These data confirm that the pelvic nerve is largely responsible for the neural and behavioral effects of VCS, and support a separate function for the hypogastric nerve.

The infralimbic cortical area commands the behavioral and vegetative arousal during appetitive behavior in the rat

The infralimbic cortical area is a good candidate to send processed motivational signals to initiate the arousing and autonomic responses that characterize appetitive behaviors. To test this hypothesis we enticed hungry rats with food while assessing locomotion (as an index of arousal level) and temperature responses, and evaluated Fos immunoreactivity (IR) in the infralimbic area and in subcortical nuclei involved in thermoregulation or arousal. We also recorded from single infralimbic neurons in freely moving rats while enticing them with food. We found that 83% of infralimbic neurons were excited or inhibited by feeding and, in particular, that 33% of infralimbic neurons increased their discharge rate during food enticing. Intact rats showed increased Fos IR in the infralimbic area, as well as in many other cortical areas. The excitotoxic lesion of the infralimbic cortex abolished the arousing and hyperthermic responses observed in intact rats, as well as the expression of Fos IR in the ascending arousal system and subcortical thermoregulatory regions. We conclude that the infralimbic area plays a central role in implementing behavioral arousing and thermal responses during an appetitive behavior.

Effects of Green Odor on Expression of Fos-immunoreactivity in the Paraventricular Nucleus of the Thalamus in Forced Swimming Rats

Experiments were performed on male Wistar rats at 8 weeks of age(Sankyo Lab., Shizuoka, Japan) and approved by the InstitutionalAnimal Care and Use Committee of the Faculty of Engineering ofToyama University. Rats were housed in a light-controlled room(light on, 06:00–18:00) at a temperature of 23 ± 1°C. Food and waterwere available

Cholecystokinin activates specific enteric neurons in the rat small intestine

Cholecystokinin (CCK) is a peptide hormone released from the I-cells of the upper small intestine. CCK evokes a variety of physiological responses, such as stimulation of pancreatic secretion, reduction of food intake and inhibition of gastric emptying. Previously, we reported that CCK activates enteric neurons in the rat. However the specific subpopulations of enteric neurons activated by CCK have not been identified. In the work reported here, we utilized immunohistochemical detection of nuclear Fos, a marker for neuronal activation, and selected phenotypic markers to identify some of the neuronal subpopulations activated by CCK. The phenotypic markers that we examined were: nitric oxide synthase (NOS), neurokinin-1 receptor (NK-1R), calbindin (Cal), Calretinin (Calr), and neurofilament-M (NF-M). We found that in the myenteric plexus of the rat duodenum and jejunum, CCK activated NOS immunoreactive neurons. In the submucosal plexus of duodenum and jejunum, CCK activated Cal, Calr and NF-M immunoreactive neurons. CCK failed to activate NK-1R immunoreactive neurons in either plexus. Our results indicate that CCK activates distinct enteric neurons in the rat upper small intestine. Furthermore the fact that NOS immunoreactive neurons were activated suggests that CCK modulates the activity of inhibitory motor neurons in the myenteric plexus. Expression of Fos immunoreactivity in Calr and Cal immunoreactive neurons is consistent with a role for CCK in modulation of intrinsic sensory and/or secretomotor neuronal activity in the submucosal plexus.

Neuropeptide Y inhibits estrous behavior and stimulates feeding via separate receptors in Syrian hamsters.

Central injections of neuropeptide Y (NPY) increase food intake in Syrian hamsters; however, the effect of NPY on sexual behavior in hamsters is not known nor are the receptor subtypes involved in feeding and sexual behaviors. We demonstrate that NPY inhibits lordosis duration in a dose-related fashion after lateral ventricular injection in ovariectomized, steroid-primed Syrian hamsters. Under the same conditions, we compared the effect of two receptor-differentiating agonists derived from peptide YY (PYY), PYY-(3-36) and [Leu(31),Pro(34)]PYY, on lordosis duration and food intake. PYY-(3-36) produced a 91% reduction in lordosis duration at 0.24 nmol. [Leu(31),Pro(34)]PYY was less potent, producing a reduction in lordosis duration (66%) only at 2.4 nmol. These results suggest NPY effects on estrous behavior are principally mediated by Y2 receptors. PYY-(3-36) and [Leu(31),Pro(34)]PYY stimulated comparable dose-related increases in total food intake (2 h), suggesting Y5 receptors are involved in feeding. The significance of different NPY receptor subtypes controlling estrous and feeding behavior is highlighted by results on expression of Fos immunoreactivity (Fos-IR) elicited by either PYY-(3-36) or [Leu(31),Pro(34)]PYY at a dose of each that differentiated between the two behaviors. Some differences were seen in the distribution of Fos-IR produced by the two peptides. Overall, however, the patterns of expression were similar. Our behavioral and anatomic results suggest that NPY-containing pathways controlling estrous and feeding behavior innervate similar nuclei, with the divergence in pathways controlling the separate behaviors characterized by linkage to different NPY receptor subtypes.

Expression of fos immunoreactivity in some catecholaminergic brainstem neurons in rats following high‐altitude exposure

Expression of fos immunoreactivity in some catecholaminergic brainstem neurons in rats following high‐altitude exposure

Expression of Fos immunoreactivity in some catecholaminergic brainstem neurons in rats following high-altitude exposure.

This study examined the response of neurons of the cardiorespiratory centers, i.e., the nucleus tractus solitarius and the ventrolateral medulla as well as the area postrema in adult and postnatal rats subjected to high-altitude exposure at 4,000 m and 8,000 m. In adult control rats, sporadic Fos-positive neurons were detected in the above-mentioned areas. On exposure to 4,000 m altitude, the number of Fos-positive neurons was noticeably increased. At 8,000 m, the incidence of labeled cells was markedly increased, with many of them doubly labeled for tyrosine hydroxylase. In postnatal rats, Fos expression was not detected in these areas in either control rats or rats exposed to 4,000 m altitude. Fos-positive cells, however, were observed in the these areas in postnatal rats exposed to 8,000 m. In the latter, tyrosine hydroxylase labeling was observed in some Fos-positive cells in the nucleus tractus solitarius and ventrolateral medulla. In rats killed at 24 hr after exposure to high altitude, Fos expression in both the adult and the postnatal rats was comparable to that in their corresponding control rats. Present results suggest that Fos expression in various brainstem areas was induced by reduced oxygen tension in the ambient air at high altitude. Double labeling of some Fos-positive neurons with tyrosine hydroxylase indicates an increased sympathetic activation, which may be involved in the mediation of cardiorespiratory responses to hypoxia. This, however, was less evident in the postnatal animals. It is possible that the peripheral chemoreceptors or the regulation of autonomic functions is not fully developed in this age group.

Expression of Fos immunoreactivity in rat brain during dehydration: effect of duration and timing of water deprivation

Water deprivation induces expression of the immediate early gene c- fos in specific brain regions, most likely as a result of the activation of cells that are responsive to changes in osmolality and/or blood volume. We hypothesized that the magnitude of c- fos expression would be a function of both the duration of water deprivation and the time of day at which the deprivation started. This study was designed to examine the pattern of Fos-like immunoreactivity (FLI) following water deprivation in rats under normal light/dark conditions (nLD) and reverse light/dark conditions (rLD). Rats were deprived of water but not food either for 0, 5, 16, 24 or 48 h. As expected, hematocrit ratio (HCT), osmolality (OSM), plasma renin activity (PRA) and weight loss increased as a function of duration of water deprivation. In non-deprived rats (0 h), very little FLI was observed in most brain regions. The number of cells showing FLI increased with duration of water deprivation in the supraoptic nucleus (SON), paraventricular nucleus (PVN), organum vasculosum laminae terminalis (OVLT), median preoptic nucleus (MnPO) and subfornical organ (SFO) in both nLD and rLD conditions. However, the pattern of FLI differed between nLD and rLD conditions. Compared to corresponding nLD groups after 5 or 24-h water deprivation, rLD groups had significantly more FLI in SON and PVN, and higher PRA and HCT. Also, weight loss and FLI in the MnPO were greater after 5 h, and FLI in the SFO was greater after 24 h under rLD compared to nLD conditions. Our findings indicate that the magnitude of c- fos expression, and change in weight and plasma parameters were a function of both the duration of water deprivation and the time of day at which the deprivation started. This may result from ingestion of food early in the deprivation periods during the rLD tests, thus producing greater change in osmolality and blood volume.

Expression of Fos immunoreactivity in the rat supraspinal regions following noxious visceral stimulation

We used immunohistochemical detection of the Fos protein to study the neuronal activation in the brain of methoxyfluorane-anesthetized rats after noxious deep somatic or visceral stimulation. The anesthesia was effective in triggering gene induction in many brain regions. Nevertheless, Fos appeared de novo in several brain nuclei following noxious stimulation in anesthetized animals. This could be of clinical relevance, as it suggests that the gas anesthetic does not suppress noxious stimulus-evoked reactivity in brain neurons. Two types of visceronociceptive stimuli were used to compare the effects of a diffuse visceral inflammation (peritoneal inflammation) with those of a more restricted inflammation (urinary bladder inflammation). In the same supraspinal areas, there were very few immunostained neurons in unstimulated controls, whereas Fos-positive cells were slightly more numerous in anesthetized controls and significantly more numerous after noxious stimulation. The peritoneal inflammation induced more Fos-labeled neurons than the restricted visceral stimulation. Labeled cells were found in these cases mainly in the ventrolateral medulla, parabrachial complex, dorsal raphe nucleus, periaqueductal gray, several hypothalamic and thalamic nuclei, amygdaloid complex, and cortex. Altogether these findings indicated that somatic and visceral inputs generally activate the same neuronal groups. However, a separation between the activation of somatic and visceral pathways was found in some brain nuclei, such as the parabrachial complex, hypothalamic, and thalamic nuclei.

C-fos can be induced in the neonatal rat spinal cord by both noxious and innocuous peripheral stimulation

The development of spinal cord nociceptive pathways has been investigated in neonatal rat pups using the expression of Fos immunoreactivity in laminae I and II cells produced by high and low intensity skin stimulation. Noxious pinch of the hindpaw evoked a clear response in the newborn rat pup, which was not significantly different from that seen at postnatal day (P) 21. Low intensity touch stimulation also produced a significant fos response in laminae I and II cells at P3 which was 60% that of the pinch response. This was reduced to 27% of the pinch response by P10 and was gone by P21. Electrical stimulation through percutaneous electrodes showed that Aβ fibre stimulation also produced a fos response at P3 that was not significantly different from that produced by C fibre stimulation. By P21 and P30 the response to C fibre stimulation was much greater and the response to A fibre stimulation was not significantly above background. The results suggest that in the neonatal spinal cord, low threshold A fibres are able to activate pathways in lamina I and II of the dorsal horn that in the adult are predominantly nociceptive.

Estrogen receptor-immunoreactive neurons are present in the female rat lumbosacral spinal cord.

Presence of an estrogen receptor is crucial for cells to respond to estrogen; thus, estrogen-responsive neurons should be identifiable by immunohistochemically staining for the estrogen receptor (ER). Even though spinal neurons are involved in sexual behaviors and innervation of genital organs, little information is available about ER-containing neurons in the spinal cord. Consequently, we have undertaken a study of ER-containing neurons in the female rat lumbosacral cord, an area involved in reproductive functions and predicted to contain estrogen-responsive neurons. In addition, since parasympathetic preganglionic neurons in the lumbosacral cord produce nitric oxide (NO), we also sought to determine if ER-immunoreactive (-IR) neurons contain the enzymes for NO production. Finally, we compared the distribution of ER-IR neurons to the presence of uterine cervix-related neurons. Uterine cervix-related neurons were identified by expression of FOS-immunoreactivity after vaginocervical mechanostimulation (VCS). The lumbosacral spinal cords were removed from intact, ovariectomized, and VCS-treated rats and sections stained by immunohistochemistry. ER-IR was present in the nuclei of neurons located predominately in the dorsal one-half of the spinal cord. Specific sites include the dorsal horn, lamina V, the sacral parasympathetic nucleus (SPN) (which contains preganglionic parasympathetic neurons) and extending into the lateral funiculus, and lamina X. Some ER-IR neurons were NADPH-d-positive and were localized in laminae V and VII. FOS-IR neurons had a distribution pattern similar to the distribution of neurons containing ER. The presence of ER neurons in these regions suggest that they are responsive to circulating estrogen.