Biomedical subjects

M Chapleur-Château

Publications and source records attributed to M Chapleur-Château.

4 recordsLinked to original sources

PubMed1998

Changes in oxytocin content in rat brain during morphine withdrawal.

In this study the modification in the oxytocin content in different hypothalamic nuclei during morphine withdrawal was analysed. Male rats were implanted with placebo (naïve) or morphine (tolerant/dependent) pellets for 7 days. On day 7, groups of rats received an acute injection of saline s.c. (control) or naloxone (1 mg/kg s.c.) and were decapitated 30 min later. After administration of naloxone to tolerant rats (withdrawal) an increase in the oxytocin content in the paraventricular nucleus (PVN) and median eminence (ME) was found. No changes were found in the arcuate nucleus (AN) and supraoptic nucleus (SON). Present data demonstrate that administration of naloxone to tolerant rats alters the brain oxytocin system, which suggests that this peptide might contribute to the behavioural, emotional and neuroendocrine response to opioid.

Animals↗

PubMed1998

Alterations in corticotropin-releasing factor and vasopressin content in rat brain during morphine withdrawal: correlation with hypothalamic noradrenergic activity and pituitary-adrenal response.

The modification in the activity of noradrenergic neurons projecting to the hypothalamus and the pituitary-adrenal response during morphine withdrawal as well its correlation with alterations in corticotropin-releasing factor (CRF) and vasopressin (AVP) content in different brain areas was analyzed. Male rats were implanted with placebo (naïve) or morphine (tolerant/dependent) pellets for 7 days. On day 8, groups of rats received an acute injection of saline s.c. (control) or naloxone (1 mg/kg s.c.) and were decapitated 30 min later. After administration of naloxone to tolerant rats (withdrawal) we found a striking parallelism between an enhanced activity of hypothalamic noradrenergic neurons and an increased corticosterone secretion; concomitantly, the CRF but not the AVP content in the paraventricular nucleus was decreased, which might reflect an increased release of the peptide. During withdrawal, CRF content also was decreased in the arcuate nucleus, whereas no changes were found in the median eminence, dorsomedial, ventromedial nuclei or in the bed nucleus of the stria terminalis. AVP content levels were not modified in arcuate nucleus, supraoptic or in the suprachiasmatic nuclei. Present data suggest that a hypothalamic noradrenergic hypersecretion may be involved in a selectively increased activity of CRF neurons in the paraventricular nucleus and arcuate nucleus and then in the enhanced release of corticosterone induced by morphine withdrawal. However, we did not find any correlation between opioid withdrawal-induced alterations in the pituitary-adrenal axis and AVP modifications.

Animals↗

PubMed1997

Differential regulation of corticotropin-releasing factor and vasopressin in discrete brain regions after morphine administration: correlations with hypothalamic noradrenergic activity and pituitary-adrenal response.

The changes in the content of corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) in discrete brain nuclei during chronic opioids administration have not been well established. We evaluated the effects of acute and chronic morphine administration on the content of CRF and AVP in different hypothalamic and extrahypothalamic (bed nucleus of the stria terminalis, BNST) nuclei in rats. Concomitantly, changes in hypothalamic noradrenaline (NA) turnover [estimated by the 3-methoxy-4-hydroxyphenylethyleneglycol MHPG/NA ratio] and in plasma corticosterone release (as a marker of the activity of the hypothalamus-pituitary-adrenal axis) were determined. Male rats were implanted with placebo (naïve) or morphine (tolerant) pellets for 7 days. On day 8, groups of rats received an acute injection of either saline i.p. or morphine (30 mg/kg i.p.) and were sacrificed 30 min later. Acute morphine injection to naïve rats increased both the release of corticosterone and the hypothalamic NA turnover. CRF and AVP showed no modifications in the paraventricular nucleus (PVN) or in the median eminence (ME). CRF content decreased in the ventromedian nucleus (VMN) and increased in the BNST, but did not change in the arcuate nucleus (AN). AVP was elevated in the supraoptic nucleus (SON) but not changed in the suprachiasmatic nucleus (SCN). In chronic morphine-treated rats, there was a pronounced decrease in the NA turnover and in the release of corticosterone, which indicates that tolerance develops to the acute effects of morphine. Correspondingly, CRF and AVP were enhanced in the PVN and decreased in the ME, when compared with naïve rats injected with morphine. CRF content was decreased in the AN and in the BNST, but increased in the VMN. The AVP content was decreased in the SON, and no modifications were seen in the SCN. The present study shows that, in addition to the modifications in corticosterone secretion and in hypothalamic NA turnover, chronic morphine administration produces a complex response in the CRF and AVP systems. These modifications might contribute to the behavioral, emotional and neuroendocrine alterations produced during opioid tolerance.

Analgesics, Opioid↗

PubMed1997

Changes in hypothalamic oxytocin levels during morphine tolerance.

The role of hypothalamic oxytocin neurons in the hypothalamus-pituitary-adrenal (HPA) axis adaptation during opioid tolerance has not been explored. In this study the modification of oxytocin levels in different hypothalamic nuclei was determined after acute or chronic morphine exposure. Male rats were implanted with placebo (naïve) or morphine (tolerant) pellets for 7 days. On day 8, groups of rats received an acute injection of either saline i.p. or morphine (30 mg/kg i.p.) and were sacrificed 30 min later. In morphine-tolerant rats, there was a decrease in the oxytocin content in the median eminence (ME) and in the supraoptic nucleus (SO) after acute injection of saline or morphine. No modifications were seen in the paraventricular nucleus (PVN). The present study demonstrates that chronic morphine administration alters the brain oxytocin system, which suggests that this peptide might contribute to the behavioural, emotional and neuroendocrine responses to opioids.

Animals↗