The analysis of the posterior thalamus revealed that about 50% of CGRP-containing neurons projected to the AStr, the projections originating in the medial part of the medial geniculate body, posterior intralaminar nucleus, parvicellular subparafascicular nucleus, and peripeduncular nucleus.
Other structures such as the central tegmental field/subparafascicular nucleus of the thalamus, central nucleus of the amygdala, and medial amygdala, also important in the display of male copulatory behavior, were less reliably labeled.
These neurons are located in the rostral part of the subparafascicular nucleus and in the subparafascicular area, caudally. Neurons from both the rostral subparafascicular nucleus and the subparafascicular area project to the medial prefrontal, insular, ecto- and perirhinal cortex, nucleus of the diagonal band, septum, central and basomedial amygdaloid nuclei, fundus striati, basal forebrain, midline and intralaminar thalamic nuclei, hypothalamus, subthalamus and the periaqueductal gray. In contrast, only the rostral part of the subparafascicular nucleus projects significantly to the superficial layers of prefrontal, insular, ectorhinal and somatosensory cortical areas. Double labeling showed that anterogradely labeled fibers from the rostral part of the subparafascicular nucleus contain TIP39 in many forebrain areas, but do not in hypothalamic areas. Injections of the retrograde tracer cholera toxin B subunit into the lateral septum and the fundus striati confirmed that they were indeed target regions of both the rostral subparafascicular nucleus and the subparafascicular area.
The subparafascicular nucleus and the subparafascicular area are the major sites of synthesis of the recently discovered neuropeptide, tuberoinfundibular peptide of 39 residues (TIP39). Thus, we have injected the retrograde tracer cholera toxin B subunit into the rostral, middle, and caudal parts of the rat subparafascicular nucleus. We report that the afferent projections to the subparafascicular nucleus and area include the medial prefrontal, insular, and ectorhinal cortex, the subiculum, the lateral septum, the anterior amygdaloid area, the medial amygdaloid nucleus, the caudal paralaminar area of the thalamus, the lateral preoptic area, the anterior, ventromedial, and posterior hypothalamic nuclei, the dorsal premamillary nucleus, the zona incerta and Forel's fields, the periaqueductal gray, the deep layers of the superior colliculus, cortical layers of the inferior colliculus, the cuneiform nucleus, the medial paralemniscal nucleus, and the parabrachial nuclei. Most of these regions project to all parts of the subparafascicular nucleus. However, the magnocellular subparafascicular neurons, which occupy the middle part of the subparafascicular nucleus, may not receive projections from the medial prefrontal and insular cortex, the medial amygdaloid nucleus, the lateral preoptic area, and the parabrachial nuclei. Overall, the afferent connections of the subparafascicular nucleus and area suggest its involvement in central reproductive, visceral, nociceptive, and auditory regulation..
c-Fos activation was also seen in the medial paralemniscal nucleus in the pons (MPL) and in the subparafascicular nucleus (SPF) in the midbrain.
Following bilateral lesions of the medial subparafascicular area including the subparafascicular nucleus, TIP39-immunoreactive fibers almost completely disappeared from forebrain regions including the anterior limbic cortical areas, the shell and cone portions of the nucleus accumbens, the lateral septum, the bed nucleus of the stria terminalis, the amygdaloid nuclei, the fundus striati, the subiculum, the thalamic paraventricular nucleus, and the hypothalamic paraventricular, dorsomedial and arcuate nuclei.
Other activated mesodiencephalic structures are the midbrain lateral central tegmental field, zona incerta, subparafascicular nucleus, and the ventroposterior, midline, and intralaminar thalamic nuclei.
The parvocellular subparafascicular nucleus of the thalamus (SPFp) consists of separate subdivisions, i.e., a medial portion containing galanin-immunoreactive (-IR) axons and a lateral portion containing calcitonin gene related peptide (CGRP)-IR neurons and fibers.
Apart from a dense afferent projection from the retina- and the contralateral leaflet, there were ipsilateral projections from other structures: layer V and VI of the prefrontal cortex, the zona incerta, the magnocellular part of the subparafascicular nucleus, the dorsal raphe nucleus, the locus coeruleus, and the cuneiform nucleus.
The medial geniculate projection was concentrated in the caudal one-third of the thalamus; in contrast, the labeling in the subparafascicular nucleus, substantia nigra, and central gray continued much further rostrally.
We examined the occurrence and severity of the Alzheimer's disease (AD)-related cytoskeletal pathology and beta-amyloidosis in the seven intralaminar nuclei (central lateral nucleus, CL; central medial nucleus, CEM; centromedian nucleus, CM; cucullar nucleus, CU; paracentral nucleus, PC; parafascicular nucleus, PF; subparafascicular nucleus, SPF) in 27 autopsy cases at different stages of the cortical neurofibrillary pathology (cortical NFT/NT-stages I-VI) and beta-amyloidosis (cortical phases 1-4).
In rats, ErbB4 expression was observed in the habenular nuclei, the paraventricular nucleus, intermediodorsal nucleus, the central medial thalamic nucleus, the posterior nucleus, the parafascicular nucleus, the subparafascicular nucleus, the suprageniculate nucleus, the posterior limitans nucleus, the medial part of the medial geniculate nucleus, the peripeduncular nucleus, the posterior intralaminar nucleus, the lateral subparafascicular nucleus, the lateral posterior nucleus, and all ventral thalamic nuclei.
In accordance with the available literature, we observed increased expression of c-fos in the medial preoptic nucleus (MPN), in the posteromedial subdivision of the bed nucleus of the stria terminalis, in the posterodorsal part of the medial amygdala, and in the caudal thalamus, in the parvicellular part of the subparafascicular nucleus. We show that the location of the Fos-IR neurons in the medial subparafascicular nucleus perfectly coincides with the location of Galanin-IR fibers, ascending from the spinal cord.
Neurons double-labeled with both tracers were found mainly in the posterior intralaminar nucleus and suprageniculate nucleus, and to a lesser extent in the subparafascicular nucleus and medial division of the medial geniculate nucleus.
Moreover, consummatory behavior increased neural activity in the subparafascicular nucleus, a brain region that receives genital sensory inputs.
Androgen receptor-immunoreactive regions included the medial preoptic area and other forebrain areas previously identified as containing androgen receptors, the dorsal and ventral periaqueductal gray, and a midbrain region that included the lateral part of the central tegmental field, part of the caudal zona incerta, the subparafascicular nucleus of the thalamus and the peripeduncular nucleus.
In addition, the parvicellular subparafascicular nucleus and the lateral part of the posterodorsal medial amygdala appear to be involved in the integration of viscero-sensory input. This was observed especially in the posteromedial bed nucleus of the stria terminalis and posterodorsal medial amygdala, but also in the parvicellular subparafascicular nucleus, ventromedial hypothalamic nucleus and ventral premammillary nucleus.
Most closely associated with attack was the path from the ventromedial hypothalamus through the ventral supraoptic commissural pathway to the peripeduncular area, subparafascicular nucleus, zona incerta, and cuneiform area.
The posterodorsal preoptic nucleus, the lateral part of the posterodorsal medial amygdala, the medial part of the sexually dimorphic area and the parvicellular part of the subparafascicular nucleus of the thalamus expressed c-Fos after ejaculation.
COX 2-ir neurons were also observed in the subparafascicular nucleus, the medial zona incerta, and pretectal area.
The retrochiasmatic area, dorsomedial nucleus, and medial supramammillary nucleus also receive significant inputs, and a few axons end in the subparafascicular nucleus, superior colliculus, and mammillary body.
Topographically and cytologically, Pf is closely related to the subparafascicular nucleus (sPf).
Other portions of this stream form the parvocellular subparafascicular nucleus and the peripeduncular nucleus.
In the course of our study on the neuronal connections of the subparafascicular nucleus (SPF) in the rat, descending projections from the SPF to the lower brain stem were examined by using the anterograde tracer PHA-L (Phaseolus vulgaris leukoagglutinin) and retrograde tracer WGA-HRP (horseradish peroxidase conjugated to wheat germ agglutinin).
The subparafascicular nucleus and the rostral portion of the lateral subparafascicular nucleus primarily projected to the medial amygdala and the amygdalostriatal transition area, while the more lateral cell groups, including the caudal part of the lateral parafascicular, posterior intralaminar, and peripeduncular nuclei projected to the lateral amygdala and the caudate-putamen.
AADC-IR neurons were localized in the ventromedial part of the thalamus, lateral posterior complex, paracentral nucleus and lateral dorsal nucleus of the thalamus, medial habenula, parafascicular nucleus, subparafascicular nucleus, and periaqueductal gray.
Following injections in the inferior colliculus, terminal labeling was present in ventral, medial, and dorsal divisions of the medial genicuate body (MGB) and in adjacent areas of the posterior thalamus, including the posterior limitans nucleus, the posterior intralaminar nucleus, the marginal zone, the peripeduncular region, the lateral or parvicellular part of the subparafascicular nucleus, and a region intercalated between the posterior limitans nucleus and the suprageniculate nucleus. At intermediate levels of the MG, however, the spinal projection began to overlap the collicular field, terminating in the medial division of the MG and in the posterior intralaminar nucleus, the marginal zone, the lateral subparafascicular nucleus, and the area between the suprageniculate and posterior limitans nuclei.
Rather essential are projections of the "posterior group nuclei", those of the suprageniculate nucleus, of some parts of the ventral thalamus (subparafascicular nucleus, marginal and peripeduncular nuclei) and parabrachial nucleus.
Cells labeled from the medullary injections were seen ventrally to the fasciculus retroflexus in the subparafascicular nucleus.
On the basis of the locations of the neurons projecting to these different areas, 3 subnuclei were delineated: the rostral interstitial nucleus of the MLF lying laterally along the medial tip of the medial lemniscus, containing a few neurons projecting to the raphé nuclei and the inferior olivary complex; the subparafascicular nucleus (spf) lying medially in the rostralmost part of the area and containing neurons projecting to the amygdala and basal ganglia; the subfascicular area of the mesodiencephalic junction lying medially and caudal to the spf and containing neurons projecting to the raphé nuclei, the inferior olive, the caudalis subnucleus of the trigeminal complex and the spinal cord.
The posterior interpositus fibers ended heavily in the central VA-VL regions, moderately in the subparafascicular nucleus and ZI, and sparsely in the CM and the ventral lateral geniculate nucleus.
Among the heavily labeled nuclear groups were the the parvocellular red nucleus, the interstitial nucleus of Cajal, the nucleus of Darkschewitsch, and the caudomedial extremity of the subparafascicular nucleus.
Retrograde transport of horseradish peroxidase injected into the olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of Darkschewitsch, the fields of Forel, the interstitial nucleus of Cajal, the periaqueductal grey, the caudal pretectal nucleus, the tegmentum dorsomedial to the red nucleus, the red nucleus (minimal), the nucleus linearis, as well as the dorsolateral midbrain tegmentum and tectum (Henkel et al., '75). Secondly, neurons within the subparafascicular nucleus, the nucleus of Darkschewitsch and the fields of Forel project most heavily to parts of the medial accessory nucleus, although they also provide input to the other major subdivisions of the olive.
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