Immunohistochemical localization of neurotensin in endocrine cells of the gut

Elevation of Plasma Neurotensinlike Immunoreactivity after a Meal

“…Interassay coefficient of variation was 9%. The cross-reactivity of TG-1 with partial sequences was as follows: NT(1-13), 100%; NT(1-12), 120%; NT(1-11), 60%; NT(l-10), 50%; NT (1)(2)(3)(4)(5)(6)(7)(8) (Fig. 2B) was pooled, redissolved in distilled water, and injected while the column was being eluted with buffer A.…”

“…2B) was pooled, redissolved in distilled water, and injected while the column was being eluted with buffer A. A linear gradient elution program (0-30% acetonitrile in buffer A) was only partially successful; standard NT(I-11) was resolved well, but NT(1-8) and NT (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) eluted at the same time as did one of the components of NTLI. Therefore, fractions from the region containing this component were pooled, lyophilized, redissolved, and analyzed using a gradient protocol that was found to be satisfactory to separate all the available immunoreactive N-terminal partial sequences of NT.…”

“…Standards were injected as the last run of each day, and identified by RIA as well as by absorbance at 210 nm. Recovery of peptides in fractions from HPLC was 75% for NT (1)(2)(3)(4)(5)(6)(7)(8), 95% for NT (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) and NT(1-11), and 99% for NT (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) RESULTS Measurements of plasma NTLI with a C-terminal directed antiserum (HC-8) did not change from basal levels, while N-terminal immunoreactivity (TG-1) rose 10-fold after ingestion of a test meal (Table I).…”

“…We have developed a procedure to separate and characterize these N-terminal cross-reacting substances, and to estimate the contributions of these constitutents to plasma neurotensinlike immunoreactivity. Gel chromatography of pooled plasma extracts on Sephadex G-25 followed by reverse-phase high pressure liquid chromatography indicated that peptides coeluting with NT and its N-terminal partial sequences NT (1)(2)(3)(4)(5)(6)(7)(8) and NT (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) were present in plasma. Comparison of plasmas collected before and 1 h after a defined meal, in five experiments, demonstrated no change in C-terminal immunoreactivity and an 8-to 10-fold rise in N-terminal immunoreactivity.…”

“…Chromatographic analysis of pooled pre-and postmeal plasma in four experiments showed that essentially all of this elevation in neurotensinlike immunoreactivity measured with an N-terminal directed antiserum was due to increases in NT (1)(2)(3)(4)(5)(6)(7)(8) and NT (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), while NT itself, measured using a C-terminal directed antiserum, did not increase appreciably in peripheral plasma 1 h after the meal. Generation of tritiated substances with the same elution times as NT (1)(2)(3)(4)(5)(6)(7)(8) and NT(1-11) did occur after incubation of [3H]NT INTRODUCTION The tridecapeptide neurotensin (NT),' which has been isolated from bovine hypothalamus (1) and bovine as well as humnan small intestine (2,3), has been localized to a population of endocrinelike cells in the distal small intestinal epithelium of many avian and mammalian species, including man (4)(5)(6)(7). Plasma neurotensinlike immunoreactivity (NTLI) is composed of several immunoreactive substances, including NT, that crossreact with N-terminal and C-terminal region-specific antisera (8).…”