Immunohistochemical detection of a substance resembling growth hormone-releasing factor in the brain of the rainbow trout (Salmo gairdneri)

We studied the distribution of an immunoreactive substance resembling growth hormone-releasing factor (GRF) in the hypothalamus and pituitary gland of the rainbow trout by immunofluorescence methods. The GRF-like immunoreactive perikaryon was observed in colchicine-treated fish. The majority of GRF-containing neurons were located in the nucleus lateral tuberis; others were located in the caudal part of the preoptic nucleus of the hypothalamus. The GRF-like immunoreactive neuronal processes projected into the pars distalis via the pars nervosa of the pituitary gland. The distribution of the GRF-like immunoreactive substance in the hypothalamus and pituitary gland suggests that GRF plays a physiological role in the regulation of growth hormone release from the pituitary gland of rainbow trout, as it does in mammals.     

Failure of (+)-naloxone to accelerate feline colonic transit

Summary To determine whether the colonic transit accelerating effect of (–)-naloxone (0.3 mg/kg, i.m.) is due to an action at opioid receptors or a direct pharmacologic effect, its enantiomer, (+)-naloxone (0.3 mg/kg, i.m.) was administered to cats and compared to saline control using colonic transit scintigraphy. Transit was not accelerated by (+)-naloxone. The effects of naloxone on colonic transit are thus stereospecific, and are probably mediated by opioid receptors.     

Mammalian pineal melatonin: a clock for all seasons

The central role of the pineal gland and its hormone melatonin (MEL) in mammalian photoperiodic responses is discussed in terms of: 1) evidence for the involvement of MEL in photoperiodism, 2) which feature of the MEL secretion profile might be most important for regulating photoperiodic responses, 3) evidence for the modulation of responses to changes in daylength based on previous photoperiod exposure (i.e., photoperiodic history) and 4) how the MEL signal might be processed at its target sites to elicit physiological responses.     

Quantitative analysis of absorption spectra and application to the characterization of ligand binding curves

The spectrum of a chromophore may change as a result of perturbations in its environment. The spectral changes resulting from the perturbation are often followed by measurements at just one or two wavelengths but it is usually no more difficult to collect entire spectra. The problem comes in analysing the data from such a series of spectra. In this paper we will suggest a simple procedure in which the spectrum observed under any particular set of conditions may be considered to consist of the sum of two distinct spectral forms. The method, which is free of any assumptions regarding the quantitative relationship between the perturbation and the extent of spectral change, defines any given spectrum in terms of an apparent molar fraction of the contributing spectral forms. The variation of this apparent molar fraction provides information from which a quantitative relationship can be developed to describe the dependence of the spectral change on the perturbant. The method is illustrated using the model system of phenol red protonation and is applied to the characterization of the binding of azide ions to cobalt-substituted carbonic anhydrase.