UCN1 occurs together with CRF in the Nucleus motorius nervi trigemini, and in the magnocellular nucleus, which send a UCN1- and CRF-containing fiber tract to the median eminence. 
Stimulation of both trigeminal nerves, contralateral Nucleus motorius nervi trigemini, nucleus sensibilis nervi trigemini and ipsilateral rostral reticular formation elicited large-amplitude excitatory postsynaptic potentials with short latencies.
This study was undertaken to identify and describe populations of brainstem neurons that project to the area of the Nucleus motorius nervi trigemini in lampreys as a first step in the study of neurons that control feeding behavior in this species. To identify these neurons, the retrograde tracer cobalt-lysine was injected into the Nucleus motorius nervi trigemini on one side of the in vitro isolated brainstem preparation of seven spawning adult lampreys (Petromyzon marinus). A densely packed column of labeled neurons was found medial to the Nucleus motorius nervi trigemini on the ipsilateral side, extending further rostrally in the isthmic region. A comparison with data from cats and rats shows that the distribution of neurons that project to the Nucleus motorius nervi trigemini is very similar in mammals and in agnathes.
Most conspicuous is the large size of the Nucleus motorius nervi trigemini, reflecting the importance of masticatory muscles for the special digging technique, which demand an intense use of the teeth for loosening the soil..
The motorical main portion, Nucleus motorius nervi trigemini consists of medium-sized as well as great polygonal neurons.
Immunoreactive nerve fibers were present in all regions containing labeled perikarya and in 1) telencephalon: septum, nucleus fasciculi diagonalis Brocae; 2) diencephalon: nucleus paraventricularis, nucleus supraopticus, nucleus suprachiasmaticus, subventricular grey, nucleus of the paraventricular organ, nucleus mamillaris, infundibular decussation, outer layer of the median eminence, posterior commissure and subcommissural organ region, habenula, nuclei dorsomedialis anterior, and dorsolateralis anterior of the thalamus; and 3) mesencephalon and rhombencephalon: stratum griseum periventriculare, stratum fibrosum periventriculare, laminar nucleus of the torus semicircularis, periventricular grey, nucleus interpeduncularis, nucleus ruber, substantia nigra, locus coeruleus, raphe nuclei, nuclei of the reticular formation, Nucleus motorius nervi trigemini, cochlear and vestibular area, and nucleus spinalis nerve trigemini.
The rhombencephalon is richly endowed with serotoninergic fibers and terminals, many labelled arborizations being found in the nuclei isthmi rhombencephali and around the Nucleus motorius nervi trigemini.
Following 3H-T or 3H-E2 injection and autoradiography, labelled cells were found in nucleus septalis lateralis (SL), nucleus preopticus medialis (POM), nucleus paraventricularis (PVN), regio lateralis hypothalami (LHy), nucleus inferior hypothalami (IH), nucleus infundibuli (IN), nucleus intercollicularis (ICo), substantia grisea centralis (GCt), nucleus taeniae (Tn), and in the reticular formation near Nucleus motorius nervi trigemini (MV).
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