The organization of axonal projections from the oval and fusiform nuclei of the bed nuclei of the stria terminalis (BST) was characterized with the Phaseolus vulgaris-leucoagglutinin (PHAL) anterograde tracing method in adult male rats. Within the BST, the oval nucleus (BSTov) projects very densely to the fusiform nucleus (BSTfu) and also innervates the caudal anterolateral area, anterodorsal area, rhomboid nucleus, and subcommissural zone. Outside the BST, its heaviest inputs are to the caudal substantia innominata and adjacent central amygdalar nucleus, retrorubral area, and lateral parabrachial nucleus. It generates moderate inputs to the caudal nucleus accumbens, parasubthalamic nucleus, and medial and ventrolateral divisions of the periaqueductal gray, and it sends a light input to the anterior parvicellular part of the hypothalamic paraventricular nucleus and nucleus of the solitary tract. The BSTfu displays a much more complex projection pattern. Within the BST, it densely innervates the anterodorsal area, dorsomedial nucleus, and caudal anterolateral area, and it moderately innervates the BSTov, subcommissural zone, and rhomboid nucleus. Outside the BST, the BSTfu provides dense inputs to the nucleus accumbens, caudal substantia innominata and central amygdalar nucleus, thalamic paraventricular nucleus, hypothalamic paraventricular and periventricular nuclei, hypothalamic dorsomedial nucleus, perifornical lateral hypothalamic area, and lateral tegmental nucleus. Moderately dense inputs are found in the parastrial, tuberal, dorsal raphé, and parabrachial nuclei and in the retrorubral area, ventrolateral division of the periaqueductal gray, and pontine central gray. Light projections end in the olfactory tubercle, lateral septal nucleus, posterior basolateral amygdalar nucleus, supramammillary nucleus, and nucleus of the solitary tract. These and other results suggest that the BSTov and BSTfu are basal telencephalic parts of a circuit that coordinates autonomic, neuroendocrine, and ingestive behavioral responses during stress.

The efferent projections of the suprachiasmatic nucleus (SCh) in the rat hypothalamus have been reexamined with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L), which displays labeled axons with the clarity of a Golgi impregnation. Fibers from the SCh can be divided into six pathways for descriptive purposes. By far the densest terminal field arising from cells in the SCh ends in a roughly comma-shaped zone between the SCh and paraventricular nucleus on the one hand and the periventricular nucleus and anterior hypothalamic area on the other. A few axons continue dorsally from this "subparaventricular zone" to pass through parvicellular parts of the paraventricular nucleus and the overlying midline thalamic nuclei to end in midrostrocaudal parts of the paraventricular nucleus of the thalamus, and a larger number continue caudally to end in the dorsomedial nucleus, dorsal parts of the cell-sparse zone surrounding the ventromedial nucleus, and the posterior hypothalamic area. The other five pathways all consist of relatively small numbers of fibers and give rise to relatively sparse terminal fields. The second pathway consists of rostrally directed fibers that end in ventral parts of the medial preoptic area and anteroventral periventricular nucleus. The third consists of anterodorsally oriented fibers that pass through the medial preoptic nucleus and adjacent regions to end ventrally in the intermediate lateral septal nucleus. The fourth consists of fibers just caudal to the third group that end in the preoptic continuation of the bed nucleus of the stria terminalis, as well as in the parataenial nucleus and rostral part of the paraventricular nucleus of the thalamus. The fifth consists of laterally directed fibers that course over the optic tract to end in the ventral lateral geniculate nucleus. And the sixth consists of fibers that course posteriorally through the anterior hypothalamic and retrochiasmatic areas to end in the cell-sparse zone between the arcuate nucleus and ventral parts of the ventromedial nucleus, as well as in adjacent parts of the lateral hypothalamic area. The distribution of projections labeled following PHA-L injections centered in the subparaventricular zone was also examined and was confirmed with retrograde tracer experiments (Watts and Swanson: J. Comp. Neurol. 258:230-252, '87). The results indicate that the subparaventricular zone projects to essentially the same regions as the SCh, only much more densely, and also sends fibers back to the SCh.(ABSTRACT TRUNCATED AT 400 WORDS)

In a previous study (Watts et al., '87) we reexamined the projections of the suprachiasmatic nucleus (SCh) with the PHA-L method and found that they could be divided conveniently into six groups of fibers. By far the densest projection ends just dorsal to the SCh in a comma-shaped region designated the "subparaventricular zone," although some fibers continue on through the paraventricular nucleus of the hypothalamus to end in the overlying midline thalamus, and others continue on to end in the dorsomedial nucleus, the region around the ventromedial nucleus, and the posterior hypothalamic area. Other relatively sparse projections from the SCh were also described to the preoptic region, lateral septal nucleus, parataenial and paraventricular nuclei of the thalamus, and ventral lateral geniculate nucleus. In addition, the same method was used to show that the subparaventricular zone projects in turn massively to these same regions, as well as back to the SCh itself and to the periaqueductal gray. The present series of experiments was designed to confirm these observations with retrograde tracer injections and to investigate the cellular and possible neurotransmitter organization of the major projections from the SCh and subparaventricular zone with a combined retrograde tracer-immunohistochemical method. For this, the distribution of neuronal cell bodies within the SCh that stain with antisera to vasopressin, vasoactive intestinal polypeptide (VIP), corticotropin-releasing factor, bombesin, substance P, neurotensin, somatostatin, thyrotropin-releasing hormone, and angiotensin II was described in detail first. Then the distribution of retrogradely labeled neurons that were also stained for one or another of these peptides was described after injections of true blue, or in some cases SITS, into the regions of the subparaventricular zone, the paraventricular and parataenial nuclei of the thalamus, the ventromedial nucleus, the dorsomedial nucleus, and the periaqueductal gray. The results confirm previous immunohistochemical and anterograde tracing studies and in addition indicate that cells in dorsal as well as ventral parts of the SCh project to each of the terminal fields examined, as do many cells in surrounding areas, including the subparaventricular zone. Our results also suggest that, at the very least, vasopressin-, VIP-, and neurotensin-stained cells in the SCh project to the subparaventricular zone, midline thalamus, and dorsomedial nucleus, and that the vasopressin and VIP-stained fiber systems are partially segregated at the level of the subparaventricular zone.(ABSTRACT TRUNCATED AT 400 WORDS)

We believe these studies are the first to consistently demonstrate prevention of a secondary humoral response after cell or organ transplantation in a pig-to-primate model. The development of sensitization to the murine elements of the anti-CD40L monoclonal antibodies suggests that nonresponsiveness to cell membrane-bound antigen (e.g., alphaGal) is a specific phenomenon and not a general manifestation of immunological unresponsiveness. T cell costimulatory blockade may facilitate induction of mixed hematopoietic chimerism and, consequently, of tolerance to pig organs and tissues.

Hindbrain norepinephrine (NE) and epinephrine (E) neurons play a pivotal role in the central distribution of sensory signals derived from the internal environment. Their projections influence the various secretory patterns of the hypothalamo-pituitary-adrenal axis and are essential for feeding and adrenal medullary responses to glucoprivation. NE and E terminals in the paraventricular nucleus of the hypothalamus (PVH) and associated hindbrain cell bodies can be virtually eliminated by PVH microinjection of a retrogradely transported conjugate of saporin (SAP, a ribosomal toxin) and a monoclonal antibody against dopamine beta-hydroxylase (dbetah), i.e. dbetah mouse monoclonal antibody conjugated to SAP (DSAP). To examine the effects of selective elimination of NE/E afferents on hypothalamo-pituitary-adrenal activation, we injected DSAP into the PVH and measured corticosterone secretion under basal circadian conditions and in response to two distinct challenges: glucoprivation and forced swim. DSAP lesions profoundly impaired glucoprivation-induced corticosterone secretion and induction of CRH heteronuclear RNA and Fos mRNA in the PVH, without impairing basal CRH mRNA expression, circadian corticosterone release, or the corticosterone response to swim stress. Thus, NE/E projections influence corticosterone secretion only in certain circumstances. They are required for the response to glucoprivation, but are dispensable for circadian activation and for the response to swim stress.

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Corticotropin-releasing hormone (CRH)-containing neurons in the paraventricular nucleus of the hypothalamus (PVN) initiate and control neuroendocrine responses to psychogenic and physical stress. Investigations into the physiology of CRH neurons, however, have been hampered by the lack of tools for adequately targeting or visualizing this cell population. Here we characterize CRH neurons in the PVN of mice that express tdTomato fluorophore, generated by crosses of recently developed Crh-IRES-Cre driver and Ai14 Cre-reporter mouse strains. tdTomato containing PVN neurons in Crh-IRES-Cre;Ai14 mice are readily visualized without secondary-detection methods. These neurons are predominantly neuroendocrine and abundantly express CRH protein, but not other PVN phenotypic neuropeptides. After an acute stress, a large majority of tdTomato cells express neuronal activation marker c-Fos. Finally, tdTomato PVN neurons exhibit homogenous intrinsic biophysical and synaptic properties, and can be optogenetically manipulated by viral Cre-driven expression of channelrhodopsin. These observations highlight basic cell-type characteristics of CRH neurons in a mutant mouse, providing validation for its future use in probing neurophysiology of endocrine stress responses.