The cytokine interleukin-1 (IL-l) has a number of biologic activities, including pronounced effects on the nervous and neuroendocrine systems. In this study, in situ histochemical techniques were used to investigate the distribution of cells expressing type I IL-1 receptor mRNA in the CNS, pituitary, and adrenal gland of the mouse. Hybridization of %-labeled antisense cRNA probes derived from a murine T-cell IL-1 receptor cDNA revealed a distinct regional distribution of the type I IL-1 receptor, both in brain and in the pituitary gland. In the brain, an intense signal was observed over the granule cell layer of the dentate gyrus, over the entire midline raphe system, over the choroid plexus, and over endothelial cells of postcapillary venules throughout the neuraxis. A weak to moderate signal was observed over the pyramidal ceil layer of the hilus and CA3 region of the hippocampus, over the anterodorsal thalamic nucleus, over Purkinje cells of the cerebellar cortex, and in scattered clusters over the externalmost layer of the median eminence.In the pituitary gland, a dense and homogeneously distributed signal was observed over the entire anterior lobe. No autoradiographic signal above background was observed over the posterior and intermediate lobes of the pituitary, or over the adrenal gland. This study therefore provides evidence for discrete receptor substrates subserving the central effects of IL-l, thus supporting the notion that IL-1 acts as a neurotransmitter/neuromodulator in brain. It also supports studies suggesting that IL-1 -mediated activation of the hypothalamic-pituitary-adrenal axis occurs primarily at the level of the brain and/or pituitary gland.Interleukin-1 (IL-l) is one of a growing number of cytokines that mediate important regulatory interactions between lymphocytes and many other cell types (see Dinarello, 1989). IL-l has also been identified as a key mediator in the acute-phase

Axonal transport and immunohistochemical methods were used to investigate the anatomical and biochemical organization of projections from the nucleus of the solitary tract (NTS) to the rostral, esophageal, part of the nucleus ambiguus (NA) in the rat. Discrete iontophoretic deposits of a retrogradely transported tracer, fluorogold, placed in the rostral NA labeled a column of cells within the NTS, termed the central part of the NTS (after Ross et al., 1985), situated just medial to the solitary tract and extending from about 300 to 1000 microns rostral to the obex. Iontophoretic deposits of the anterogradely transported tracer, Phaseolus vulgaris-leucoagglutinin (PHA-L), placed in the central part of the NTS gave rise to dense and topographically restricted projections to the rostral NA. More caudal and ventral aspects of the NA did not receive prominent inputs from the central part of the NTS, and deposits that spared the central part of the NTS gave rise to only sparse projections to the rostral NA. Antisera against somatostatin-28 (SS-28) stained cell bodies within the central part of the NTS. In addition, a double-labeling procedure, capable of colocalizing anterogradely transported PHA-L and endogenous peptides to individual fibers and/or terminals, demonstrated an appreciable number of SS-28-immunoreactive terminals within the rostral NA that arose from the NTS. Correspondingly, unilateral lesions that involved the central part of the NTS resulted in a marked depletion of SS-28 immunoreactivity in the ipsilateral rostral NA. These data provide evidence for a discrete, partly somatostatinergic, projection from the central part of the NTS to the rostral NA. Anatomical and physiological studies implicating the central part of the NTS and the rostral NA in esophageal function suggest this pathway to be involved in the reflex control of esophageal motility.

The cytokine interleukin-1 (IL-1) has been reported to inhibit the hypothalamic-pituitary-gonadal axis, both through actions in brain and at the gonadal level. Recently, high affinity binding sites for ¹²⁵I-recombinant human IL-1α have been identified in the mouse testis with characteristics similar to those of type I IL-1 receptors on T lymphocytes and fibroblasts. The present study employed in situ hybridization histochemistry with ³⁵S-labeled antisense cRNA probes derived from a murine type I IL-1 receptor cDNA to identify type I IL-1 receptor mRNA in the mouse testis. An intense signal was observed over interstitial cells, and over the cytoplasm of the epithelium of epididymal ducts, most prominently in the head region. The signal over seminiferous tubules, and over sperm cells within tubules and epididymal ducts, was comparable to background. This distribution of type I IL-1 receptor mRNA was similar to that recently reported for ^125II-IL-1-α binding sites, and supports evidence implicating IL-1 as a direct regulator of gonadal function.