Effect of substance P on the 5,7-dihydroxytryptamine induced alteration of the postnatal development of central serotonin neurons

Systemic treatment with the serotonin neurotoxin 5,7-dihydroxytryptamine [5,7-HT]in the neonatal stage leads to a permanent alteration of the postnatal development of the serotonin neurons in rat brain with denervation of distant nerve terminal projections and hyperinnervation in regions close to the serotonin perikarya. Intracisternal administration of substance P was found to counteract both the denervation and the hyperinnervation, as evaluated by measuring endogenous serotonin levels and [3H]-serotonin uptake in vitro. Furthermore, substance P was found to potentiate the reduction of serotonin induced by tryptophan hydroxylase inhibition with alpha-propyldopacetamide, indicating that substance P can produce an increase in serotonin utilization and turnover. The results suggest that substance P has a degeneration preventing and/or regrowth stimulatory effect on damaged serotonin neurons during ontogeny.     

Limitation of reproductive success by food availability and litter size in the bank vole,Clethrionomys glareolus

Food limitation has been suggested as one of the most important factors affecting life history evolution in terrestrial vertebrates. However, this inference is based mainly on evidence from birds, and reproductive trade-offs may differ among groups with different forms of parental care. To study whether the costs of enlarged litters (decreased mass of offspring) would appear when food is not limiting, we performed outdoor enclosure experiments in which we manipulated simultaneously the litter size (control versus litter plus two pups) and food availability (control versus food-supplemented) of female bank voles, Clethrionomys glareolus. The weaning success of females increased significantly in response to supplementary food. When females were provided with extra food, no differences were observed in body masses of weanlings of control and enlarged litters. Further, food-supplemented females grew to larger sizes during nursing than unsupplemented females. Our experiment suggests that energetic requirements during nursing constrain the number of offspring that can be raised successfully in a particular breeding attempt. The results also indicate that unlimited food resources may increase future reproductive potential of females because they can use more energy for somatic growth.     

Effect of substance P on neonatally axotomized noradrenaline neurons in rat brain

Transection (axotomy) of the dorsal tegmental noradrenaline bundle in the neonatal stage leads to a permanent degeneration of noradrenaline nerve terminal projections distal to the lesion (e.g. in the neocortex), while projections proximal to the lesion increase their nerve terminal density (e.g. in the cerebellum). These structural changes are reflected by marked reductions and elevations respectively of the endogenous noradrenaline levels, [3H]-noradrenaline uptake in vitro and nerve density as demonstrated by fluorescence histochemistry. Intracisternal administration of substance P after the transection did not alter these noradrenaline parameters in the neocortex, whereas dose-dependent and significant increases were found in the cerebellum and pons-medulla. The results indicate that substance P may have a growth-stimulatory effect on damaged locus coeruleus noradrenaline neurons in the CNS during ontogeny.     

Purification and properties of the mercuric-ion-binding protein MerP.

The gene merP, coding for a mercuric-ion-binding periplasmic protein (P protein), was cloned into the expression vector pCA. In an Escherichia coli strain bearing the resulting plasmid, the P protein constitutes about 20% of total soluble protein. P protein was purified using ammonium sulfate precipitation and two chromatography steps. Typical yields were 20-30 mg from 7.5 l bacterial culture. The protein is a monomer with a molecular mass of 7500 Da. The periplasmic signal peptide was processed identically in both the recombinant and the wild-type proteins. CD spectra of both proteins were identical and indicated that the structure is highly ordered, containing approximately 80% alpha-helix. Purification in the presence of excess cysteine resulted in a form of the protein containing two reduced thiols, in agreement with the published sequence which has two cysteine residues. When cysteine was omitted from the purification buffers, no reduced thiol groups could be detected suggesting that the cysteine residues are oxidized. Both of these forms of the protein were found to bind approximately five Hg2+ ions/protein molecule in an apparently non-specific manner. However, in the presence of external thiol compounds, the protein with reduced thiols bound only one Hg2+ ion/protein molecule with an apparent Kd of 3.7 +/- 1.3 microM. Under these conditions, the protein with oxidized thiols did not bind Hg2+. The possible physiological role of this protein in Hg2+ detoxification is discussed.     

Antibodies to the C-terminus of the cholecystokinin precursor: radioimmunoassay and immunohistochemical studies in adult and developing rat gut

Antibodies to the extreme C-terminal pentapeptide of procholecystokinin, YEYPS (in the single letter notation), have been used in radioimmunoassay and immunohistochemistry to characterize the material in rat intestine. There is a single major immunoreactive peptide in intestinal extracts that has the properties of the C-terminal tryptic peptide of the CCK precursor. Similar material has previously been found in rat brain. In immunohistochemistry, a population of cells in rat small intestine is revealed, these also contain C-terminal gastrin/CCK activity, but for the most part do not react with gastrin-specific antibodies. During postnatal development their numbers increase considerably. We conclude that the C-terminal flanking peptide of proCCK is a useful marker for sites of CCK production.