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S E Leeman

Publications and source records attributed to S E Leeman.

At least 127 records · Page 7Linked to original sources
PubMed1979

The amino acid sequence of bovine hypothalamic substance P. Identity to substance P from colliculi and small intestine.

Bovine substance P has been isolated in pure form from hypothalamic fragments and its complete amino acid sequence determined by studies performed on the intact peptide and on its isolated papain-generated fragments. Direct evidence for the positioning of each residue was obtained, amide assignments were unequivocally established, and the COOH-terminal residue was isolated and identified as Met-NH2. The results of total enzymic digestion performed on each of the peptides obtained argue against the presence of any non-amino acid constituents in the molecule. The amino acid sequence obtained is identical with that previously reported for material isolated form bovine colliculi and from equine small intestine.

Amino Acid Sequence↗
PubMed1979

Electron microscopic localization of substance P and enkephalin in axon terminals related to dendrites of catecholaminergic neurons.

Morphological and pharmacological data suggest that catecholaminergic neurons receive afferent axons positively labeled for the peptides, substance P and [Met5]-enkephalin. In the present study, electron microscopic immunocytochemistry was used to determine whether a positive reaction for these peptides could be localized to axon terminals forming synapses with catecholaminergic neurons in the locus coeruleus and A2 regions of rat brain. Adjacent sections through these areas were incubated with antiserum to either substance P, [Met5]-enkephalin, or tyrosine hydroxylase, a specific marker for catecholaminergic neurons. The sections were subsequently processes by the peroxidase-antiperoxidase immunocytochemical technique. In both the locus coeruleus and A2 region, tyrosine hydroxylase was localized primarily to perikarya and dendrites of intrinsic neurons; whereas substance P and enkephalin-like immunoreactivity was localized to axons and axon terminals. The axon terminals showing positive reactions for substance P and [Met5]-enkephalin were morphologically similar to each other and to one type of axon terminal which formed synapses with dendrites labeled for tyrosine hydroxylase. This type of axon terminal always formed asymmetric synaptic junctions and contained 3-4 large (75-100 nm) dense vesicles (LDVs) and many small (40-60 nm) clear vesicles (SCVs). The reaction product for substance P and [Met5]-enkephalin was distributed throughout the lumen of the LDVs and formed a rim of labeling around the outer boundaries of the SCVs. These findings demonstrate that substance P and [Met5]-enkephalin-positive reactions are selectively localized to subcellular organelles in axon terminals in the locus coeruleus and A2 region of rat brain. They further suggest that the labeled axon terminals form synapses with dendrites of the catecholaminergic neurons.

Animals↗
PubMed1979

Enkephalin inhibits release of substance P from sensory neurons in culture and decreases action potential duration.

Sensory neurons grown in dispersed cell culture in the absence of non-neuronal cell types contain immunoreactive substance P that is chemically similar to synthetic substance P. When depolarized in high-K+ media (30-120 mM), the neurons release this peptide by a Ca2+-dependent mechanism. An enkephalin analogue, [D-Ala2]enkephalin amide, at 10 micron inhibits the K+-evoked release of substance P. At the same or lower concentrations, [D-Ala2]enkephalin amide and enkephalin decrease the duration of the Ca2+ action potential evoked and recorded in dorsal root ganglion cell bodies without affecting the resting membrane potential or resting membrane conductance. This modulation of voltage-sensitive channels may account for the inhibition of substance P release.

Action Potentials↗
PubMed1978

The amino acid sequence of radioimmunoassayable neurotensin from bovine intestine.

The amino acid sequence of radioimmunoassayable neurotensin, isolated from bovine small intestinal extracts, has been shown to be the same as that of the peptide originally isolated from bovine hypothalamic extracts. This was accomplished by sequence studies on the intact peptide as well as on its chymotryptic and papain-generated fragments. Thus, neurotensin joins the group of biologically active peptides shown to be present in the same molecular form in both brain and intestine.

Amino Acid Sequence↗
PubMed1977

On the origin of substance P and glutamic acid decarboxylase (GAD) in the substantia nigra.

Knife cuts in the frontal plane separating the anterior part of the caudate-putamen from the globus pallidus resulted in marked decreases in substances P levels in the reticular part of the substantia nigra. More caudal knife cuts were required in order to effect maximal decreases in nigral glutamic acid decarboxylase levels. Thus, there is a clear anatomical dissociation between the striatal neurons which project to the reticular part of the substantia nigra and which contain SP, and the more caudally located GAD-containing striatal and pallidal neurons, all of which travel through the globus pallidus on their way to the substantia nigra.

Animals↗
PubMed1977

Ultrastructure of the gut neurotensin cell.

In mammals, neurotensin cells occur scattered in the epithelium of the jejunum-ileum. In chicken, neurotensin cells are abundant in the region of the gizzard-duodenal junction (antrum) where they occur intermingled with numerous somatostatin and gastrin cells. The neurotensin cells in chicken, dog and man were identified at the electron microscopic level by immunocytochemistry, using the consecutive semithin/ultrathin section technique. They contain numerous electron dense cytoplasmic granules, pre-dominantly in the basal portion of the cell. It was shown that these granules are the storage site for neurotensin. The neurotensin granules are round, highly electron dense and of about the same size in the different species examined (mean diameter 260--290 nm). In dog and man the granules have a tightly applied surrounding membrane while in the chicken a relatively electron lucent zone separates the electron dense core from the granule membrane. The ultrastructure of the neurotensin granules in chicken is somewhat reminiscent of that of the gastrin granules. The mean diameter of the gastrin granules in chicken antrum is 230 nm; for the somatostatin granules the mean diameter is 305 nm.

Animals↗
PubMed1977

Evidence for substance P in the striato-nigral tract.

The highest concentration of substnace P yet found in the mammalian brain is in the reticular part of the substantia nigra. The effect of various lesions on the substance P content of that region has been examined in the rat in order to determine the possible sources and paths of nigropetal substance P-containing fibers. Unilateral knife cuts which transect the medial forebrain bundle and medial portion of the crus cerebri at a premammillary level lead to a 90% reduction in substance P in the ipsilateral reticular part of substantia nigra, with no significant effect on contralateral values. Incomplete electrolytic lesions of the globus pallidus lead to a 50% decrease. These data indicate that descending uncrossed pathways provide most of the substance P in the reticular part of the substantia nigra, with the striato-nigral tract providing an important component.

Afferent Pathways↗
PubMed1977

Immunohistochemical localization of neurotensin in endocrine cells of the gut.

Endocrine cells displaying neurotensin immunoreactivity are found scattered in the jejuno-ileum of all mammals studied, including man. They are rather scarce in rat, guinea pig, rabbit and pig and fairly numerous in cat, dog and man. In most mammals the neurotensin cells predominate on the villi. Only in the dog are they more numerous in the crypts. In the chicken, neurotensin cells occur all along the intestinal tract. They are particularly numerous in the zone that joins the gizzard with the duodenum. The ontogeny of the neurotensin cells in the gut was studied in rats and chickens. In the rat, the cells are first observed in the jejuno-ileum immediately before birth. The adult frequency is reached 4-5 days later. In the chicken, neurotensin cells first appear in the colon in the 18 day old embryo and in the small intestine two days later (i.e. one or two days before hatching). A few days after hatching, the gut has achieved the adult number of neurotensin cells per unit area.

Age Factors↗
PubMed1977

Substance P.

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Animals↗
PubMed1977

The aromatization of androgens by primary monolayer cultures of fetal rat hypothalamus.

Aromatization of [3H]androstenedione and [3H]19-hydroxyandrostenedione to [3H]estrone has been demonstrated to occur in one to two week old primary monolayer cultures of fetal rat hypothalamus. Three times more estrone is produced from 19-hydroxyandrostenedione than from androstenedione in four day incubations. Cultures treated with cytosine arabinoside have 50% less cellular protein and produce three times more estrone from either substrate than untreated cultures. Time course experiments using cultures treated with cytosine arabinoside indicate that aromatization of 19-hydroxyandrostenedione is linear for three days and can be quantitatively measured within the first two to eight hours of incubation.

Androstenedione↗