Plasma concentrations of total and free corticosterone during development in the rat.

Abstract

A sensitive protein-binding assay has been used to measure plasma concentrations of total corticosterone during postnatal development in the rat. These concentrations were extremely low on days 6--12, showed a significant rise by day 14, and then continued to rise until peaking on day 24. Plasma titers of corticosteroid-binding globulin rose even more dramatically from day 12 onward. Consequently, the percentage of total plasma corticosterone, which was protein-bound, showed a gradual rise from 78% on day 12 to 98% on day 24. Despite this trend, when concentrations of free corticosterone were calculated, they were found to have a developmental profile very similar to that of total corticosterone. Assay of jejunal lactase and sucrase in the same animals that were used for the corticosterone studies showed that the ontogenic rise of both total and free corticosterone preceded the developmental changes in the activities of these enzymes by approximately 2 days. The data suggest that the rise in free corticosterone that begins on day 14 acts as a cue for enzymic changes in both liver and intestine.

Developmental responses to opioids reveals a lack of effect on stress‐induced corticosterone levels in neonatal rats

“…The absence of stress-induced rises in corticosterone due to saline injection at day 10 confirms results with other stressors where adrenal responses are not apparent at this age (Haltmeyer et al, 1966;Henning, 1978), although recently rises in corticosterone due to ether, electroshock or hypoxia have been demonstrated in 10 day old rat pups (Walker et al, 1986). Also in common with most forms of stress activation (Haltmeyer et al, 1966;Allen & Kendall, 1967;Kakihana et al, 1974), injection causes marked elevations by postnatal day 21.…”

“…In particular there is evidence that stress responses are modulated by opioids. For example footshock alters levels of plasma P-endorphin and hypothalamic [Leu] enkephalin (Rossier et al, 1977;1978) and adrenalectomy lowers the content of hypothalamic opioid peptides (Gibson et al, 1980). In addition the basal and stress-induced secretion of 'Author for correspondence.…”

Developmental and geographic variation in stress hormones in wild Belding's ground squirrels (Spermophilus beldingi)

“…To date, most research on adrenal effects on behavioral and physiological development has used captive animals which can be repeatedly bled. For example, corticosterone levels of young laboratory rats (Rattus norvegicus) increase to adult levels by the age of weaning after a stress hyporesponsive period shortly after birth when levels are extremely low (Henning, 1978;Sapolsky and Meaney, 1986). Corticosterone levels of captive American kestrel (Falco sparverius) nestlings increase from very low baseline after hatching to adult levels by 22 days of age (Love et al, 2003).…”

Postnatal Changes and Effects of Glucocorticoid on MUC5AC mRNA Expression in the Rat Stomach

“…RNase-free DNase and pGEM®-T Easy Vector Systems were obtained from Promega Co. (Madison, WI, U.S.A.). M-MLV Reverse Transcriptase, Oligo-(dT) [12][13][14][15][16][17][18] Primer, RNase inhibitor, dNTP Set, and Taq DNA Polymerase, recombinant were from Invitrogen Corp. (Carlsbad, CA, U.S.A.). T7 and SP6 RNA Polymerase, DIG RNA Labeling Mix, Blocking Reagent, Anti-Digoxigenin-AP Fab fragments, Nitroblue tetrazolium chloride, and 5-bromo-4-chloro-3-indolyl-phosphate, 4-toluidine salt were obtained from Roche Diagnostics GmbH (Mannheim, Germany).…”

“…Reverse Transcription Polymerase Chain Reaction (RT-PCR) Total RNA treated with RNase-free DNase for 30 min at 37°C was denatured and reverse transcribed to single-stranded cDNA by an incubation for 60 min at 37°C with reaction mixture (100 U of Moloney murine leukemia virus reverse transcriptase, 0.5 mg oligo-(dT) [12][13][14][15][16][17][18] primer, 0.5 U RNase inhibitor, 0.5 mM of each dNTP, 10 mM dithiothreitol, 75 mM KCl, and 3 mM MgCl 2 in 50 mM Tris-HCl buffer, pH 8.3. Rat sense and antisense primer sequences were designed based on GenBank entries (rat MUC5AC (product size: 534): sense, 5Ј-GGCCAATGCGGCACTTGTACCAAT-3Ј; antisense, 5Ј-GTCATCTGGACAGAAGCAGCCCTC-3Ј; rat PgC (product size: 421): sense, 5Ј-CCAACCTGTGGGT-GTCTTCT-3Ј; antisense, 5Ј-TAGAGGTTCTTGTCCACG-CC-3Ј; rat PgF (product size: 462): sense, 5Ј-GATCATTG-CCTGTGATGGTG-3Ј; antisense, 5Ј-GGTCAGCTTCCTG-GATGAAA-3Ј; glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (product size: 306): sense 5Ј-AGCCTTCTCCA-TGGTGGTGAAGAC-3Ј; antisense, 5Ј-CGGAGTCAACG-GATTTGGTCGTAT-3Ј).…”