Presented at the 2012 AAPM Annual Meeting « Back

Comparison of Antinociceptive Effects of Morphine Between Male and Female Rats

Faezeh Nemati Karimooy, Medical Student, nematif871@mums.ac.ir¹, Mahmoud Hosseini, PhD¹, (1) Mashhad University of Medical Sciences, Mashhad, Khorasan Razavi, Iran

Introduction: The role of gonadal hormones on pain perception has been widely investigated. In the present study the differences of morphine—induced antinociception between male and female rats—was investigated. Materials & Methods: Twenty rats were divided into two groups: 1) female, 2) male. All animals were tested on the hot plate test (52±0.2 °C; Cut-off 80 sec) for evaluating the antinociceptive effects of morphine. The hot plate test was performed as a base record 15 minutes before injection of morphine (10 mg/kg; s.c.) and consequently repeated every 15 minutes after morphine injection. Results: There were no significant differences in baseline latencies among two groups. Reaction time after injection of morphine in male group was higher than female group (P < 0.01). Conclusion: It is concluded that sex hormones such as testosterone and estrogen have a role in pain perception and analgesia. References: 1)South SM, Edwards SR, Smith MT. Antinociception versus serum concentration relationships following acute administration of intravenous morphine in male and female Sprague-Dawley rats: differences between the tail flick and hot plate nociceptive tests. Cli 2)Mitsushima D, Takase K, Takahashi T, Kimura F. Activational and organisational effects of gonadal steroids on sex-specific acetylcholine release in the dorsal hippocampus. J Neuroendocrinol ( 2009); 21:400-5. 3)Loyd DR, Murphy AZ. Androgen and estrogen (alpha) receptor localization on periaqueductal gray neurons projecting to the rostral ventromedial medulla in the male and female rat. J Chem Neuroanat (2008); 36 : 216-26. 4)Silva E , Quiñones B , Páez X, Hernández L. Effect of a simple morphine system injection in some aminoacids in the anterior cingulate cortex during acute pain. Invest Clin (2008); 49: 511-22. 5)Zhu Z, Bowman HR, Baghdoyan HA, Lydic R. Morphine increases acetylcholine release in the trigeminal nuclear complex. Sleep ( 2008 ); 31:1629-37. 6)Yang XF, Xiao Y, Xu MY. Both endogenous and exogenous ACh plays antinociceptive role in the hippocampus CA1 of rats. J Neural Transm (2008); 115:1-6. 7)Ojewole JA. Analgesic, anti-inflammatory and hypoglycaemic effects of Securidaca longepedunculata (Fresen.) [Polygalaceae] root-bark aqueous extract. Inflammopharmacology (2008) ; 16:174-81. 8)Craft RM. Modulation of pain by estrogens.Pain (2007); 132: S3–S12. 9)Loyd DR , Morgan MM , Murphy AZ. Morphine preferentially activates the periaqueductal gray-rostral ventromedial medullary pathway in the male rat: a potential mechanism for sex differences in antinociception.Neuroscience ( 2007); 147: 456-68. 10)Wiesenfeld-Hallin Z. Sex differences in pain perception. Gend Med (2005); 2:137-145.

Funding: None