Naloxone but not glycyrrhizic acid modifies stress induced changes in brain serotonin levels

O. Ainsah, Nabishah Mohamad, C. B. Osman, B. A K Khalid

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Repetitive stress results in decreased blood pressure and locomotor activity which subsequently returned to normal values with adaptation. These effects could be blocked by naloxone, an opioid antagonist and glycyrrhizic acid, a modifier of tissue steroids. The effects of repetitive restraint stress (RS) in rats assessed by the levels of serotonin (5-HT) in the hypothalamus, frontal region and brain stem and their modification by naloxone and glycyrrhizic acid were studied. The 5-HT levels were measured using high performance liquid chromatography on day 0 (basal), 24 hours after the 1st, 4th, 7th and 13th exposures to RS. The basal levels were highest in the hypothalamus and lowest in the frontal region. Following the first exposure to RS the 5-HT levels were significantly reduced in all the 3 brain regions studied. These levels remained low until the 7th exposure to RS when they returned to basal indicating adaptation. In the hypothalamus with repetitive RS, the 5-HT levels in the rats treated with naloxone increased significantly and returned to basal by the 10th exposure, a mirror image to that seen for controls and rats treated with GCA. In the brain stem the 5-HT levels remained unchanged with naloxone, whilst it was similar to that seen in controls in the frontal region. GCA did not affect the 5-HT levels in response to stress in all 3 regions of the brain. In conclusion RS reduced brain 5-HT levels in all 3 regions and these returned to basal with adaptation. However, naloxone, but not GCA, modified these effects in the hypothalamus only, suggesting that the hypothalamic 5-HT levels were modulated by endogenous opioids released during stress.

Original languageEnglish
Pages (from-to)121-127
Number of pages7
JournalAsia Pacific Journal of Pharmacology
Volume14
Issue number4
Publication statusPublished - 2000

Fingerprint

Glycyrrhizic Acid
Naloxone
Serotonin
Brain
Hypothalamus
Brain Stem
Narcotic Antagonists
Locomotion
Opioid Analgesics
Reference Values
Steroids
High Pressure Liquid Chromatography
Blood Pressure

Keywords

  • Glycyrrhizic acid
  • Naloxone
  • Serotonin

ASJC Scopus subject areas

  • Pharmacology

Cite this

Naloxone but not glycyrrhizic acid modifies stress induced changes in brain serotonin levels. / Ainsah, O.; Mohamad, Nabishah; Osman, C. B.; Khalid, B. A K.

In: Asia Pacific Journal of Pharmacology, Vol. 14, No. 4, 2000, p. 121-127.

Research output: Contribution to journalArticle

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