Abstract.The effects of intranasal and iv administration of His-D-Trp-Ala-Trp-D-Phe-LysNH2

The electron spin resonance line shapes of randomly oriented molecules in septet and nonet states are analyzed in terms of the formulas derived from a perturbation treatment to third-order in the fine-structure energy. The method is applied to a ground-state septet hydrocarbon, 3, 3'diphenylmethylenebis (phenylmethylene), and a ground-state nonet hydrocarbon, mphenylenebis[(diphenylmethylen-3-yl)methylene], randomly oriented in mixed polycrystalline powders of benzophenone. It is shown that the g factor and the fine-structure parameters are determined from the line shapes of a K-band spectrum with nearly the same accuracy as in a single-crystal experiment. Extra lines have been observed in addition to the canonical lines corresponding to the external magnetic field along the principal axes of the fine-structure tensor. The appearance of extra lines in the spectra of septet and nonet molecules is discussed relative to the third-order perturbation theory.

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The present study was designed to examine the effects of intracerebroventricular injection of His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂ (GHRP) on GH secretion in freely moving conscious male rats and to determine whether the central action of GHRP is mediated by increased GHRH and/or somatostatin (SRIF) release. A significant and dose-related suppression of natural fluctuations in plasma GH occurred immediately after intracerebroventricular injection of GHRP at the doses of 1, 3 and 10 µg/rat and was sustained for more than 1 h. An intracerebroventricular injection of GHRP also suppressed plasma GH rises after an intravenous injection of [D-Ala², Nle²⁷] human GHRH (l-28)agmatine (hGHRH analog), but the GH suppression by intracerebroventricular GHRP was significantly blunted in rats treated with antirat SRIF γ-globulin (SRIF-ab). In addition, the suppression by intracerebroventricular GHRP of hGHRH-analog-induced GH release was observed even in rats treated with anti-rat GHRH goat γ-globulin (GHRH-ab) which does not cross-react with hGHRH analog, and again its suppression was significantly attenuated by simultaneous treatment with SRIF-ab and GHRH-ab. Furthermore, intracerebroventricularly injected GHRP was effective enough to inhibit the central-nervous-system (endogenous GHRH)-driven natural GH-secre-tory surges in SRIF-ab-treated rats. When 10 µg/kg GHRP was injected intravenously every 1 h during a 7-hour observation period in control rats without antibody treatment, plasma GH levels were increased with the peak 10 min after each injection during the surge period of the GH-secretory rhythm, but the plasma GH response to GHRP was frequently absent during its trough period. In addition, in SRIF-ab-treated rats, basal GH levels as well as plasma GH peaks after GHRP injections were markedly elevated and the obvious plasma GH rises after GHRP could be observed even during the trough period. In GHRH-ab-treated rats, basal GH levels were lower, and the plasma GH response to GHRP was significantly attenuated as compared with those in control rats. Plasma GH peaks after GHRP injections in rats simultaneously treated with SRIF-ab and GHRH-ab were higher than those in rats given GHRH-ab alone, but its difference in GH response was obviously smaller than that observed between SRIF-ab-treated and control rats, suggesting a crucial role of endogenous GHRH in GHRP-induced GH release. To further clarify the interaction of GHRH and GHRP in GH release, hGHRH analog was injected intravenously alone or simultaneously with GHRP in rats treated with SRIF-ab and GHRH-ab. The peak GH values after simultaneous injection of hGHRH analog and GHRP were significantly higher than the sum of GH peaks after each injection of hGHRH analog and GHRP. In conclusion, an intracerebroventricular injection of GHRP suppresses GH secretion by a central mechanism which is likely to include increased SRIF release, reduced GHRH release or both. We have confirmed that intravenous injection of GHRP can stimulate GH release by itself...

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