The noradrenaline (NA)-containing innervation of the hippocampal formation arises exclusively in the brainstem nucleus locus coeruleus. The projection is 75--90% ipsilateral, originating predominantly in the large, multipolar cells of the compact component of the nucleus. The axons course into the hippocampal formation by three pathways. Ammon's horn receives its NA innervation principally through the ventral amygdaloid bundle-ansa peduncularis, with smaller contributions from the fornix and ipsilateral fasciculus cinguli. The innervation of the area dentata is to a larger extent bilateral, with the greatest contribution arising from the ipsilateral fasciculus cinguli and approximately equal proportions of fibers traveling via the contralateral cingulum, fornix, and the ventral path. In general, the endogenous content of NA is greater in the area dentata than in Ammon's horn, and in both structures is greater in the temporal than in the septal ends. The pattern of NA innervation is similar at all septotemporal levels, however. The dense plexuses of preterminal and terminal elements appear in the infragranular hilus of the area dentata, stratum lucidum of CA3, and in the molecular layer of the subiculum. Fluorescent varicosities often appear in perisomatic clusters, or, closely apposed to dendrites of granule and pyramidal cells.

The catecholamine (CA) innervation of the posterior basal forebrain, the amygdala, suprarhinal cortex and entorhinal cortex, was studied in the rat using biochemical assay and fluorescence histochemistry. The assay studies demonstrate a moderate norepinephrine (NE) content in the amygdala and entorhinal cortex with a lower value for the suprarhinal cortex. Following destruction of the locus coeruleus, the decrease in NE content of these basal forebrain structures indicates that their principal NE innervation is from locus coeruleus. An additional small NE input arises from the medullary NE neuron groups. Ablation of dopamine (DA) cell groups (substantia nigra-ventral tegmental area, SN-VTA) indicates that the DA input to the amygdala arises from the lateral VTA and medial half of the SN. Fluorescence histochemical studies using the glyoxylic acid-Vibratome technique demonstrate the presence of four distinct types of CA neuron terminal plexus in the posterior basal forebrain. These include two different DA fiber types arising in SN-VTA, small NE fibers with small varicosities arising in locus coeruleus and NE fibers with larger varicosities arising in other brainstem NE cell groups. The large NE fibers appear to enter the amygdala via the ansa peduncularis-ventral amygdaloid bundle to innervate the central and basolateral nucleus and the anterior amygdaloid area. The locus coeruleus NE fibers appear to enter the posterior basal forebrain via both the stria terminalis and ansa peduncularis-ventral amygdaloid bundle system to form a moderately dense innervation of the central and basolateral nuclei of the amygdala and a less dense innervation of the other areas. The DA neuron axons are concentrated in the central and basal nuclei and intercalated cell groups. Other areas receive a more diffuse DA input, with the exception of the moderately dense innervation of the suprarhinal cortex and DA "islands" in the ventral-anterrior entorhinal cortex, The DA input to the posterior basal forebrain is complex and heterogeneous and the axonal morphology differs greatly among the terminal fields within the amygdala and adjacent cortical areas.

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3-Chloro-L-alanine (CA) was found to inhibit the growth of Salmonella typhimurium. The inhibition was overcome by isoleucine plus valine. CA inhibited the activity of threonine deaminase and transaminase B in vitro. The inhibition of threonine deaminase was reversible and was not affected by desensitization to isoleucine inhibition. Transaminase B was irreversibly inactivated. Derepression of some of the isoleucine and valine biosynthetic enzymes was achieved by growth of wild-type cells on low levels of CA.