[Role of estrogen on prevention of morphine addiction in ovarectomized female rats]

Evidence indicates that the biological response and the causes of drug abuse may be different between women and men. These sex differences in drug abuse may be due to socio-cultural factors or biological [hormonal] differences. Estrogen is one of the hormones which involves in dopamine release in striatum and nucleus accumbency and also is one of the most important neurotransmitters in central nervous system which has critical role in morphine addiction. So, in this study we survey the role of estrogen on dependency and tendency to morphine in rat as a factor of sex differences in addiction. This experimental study was carried out in Yazd University of Medical Sciences. Behavioral changes like morphine craving was evaluated by self-administration as a criterion for tendency and for assessment of dependency. we evaluated withdrawal syndrome sings [e.g. jumping, wet dog shaking, etc] in control group [ovarectomized female rats receiving morphine sulfate solution] and test group [ovarectomized female rats, pretreated with estradiol benzoate before receiving daily morphine sulfate solution]. Data obtained were analyzed by SPSS software, using T-test analysis. Results showed that although pretreatment with estradiol in test group might lead to a significant decline in withdrawal syndrome sings in comparison with control group, differences in morphine craving as a criterion for tendency was not significant between the two groups. According to our findings, it seems that estrogen, through central mechanisms and its effect on brain dopaminergic system, reduces the physical dependency to morphine

[Matricaria chamomilla extract infusion in to nucleus paragigantocellularis attenuates most of morphine withdrawal syndrome signs in rats]

Some reports show that co-administration of Matricaria chamomilla [MC] extract with morphine, greatly attenuate the development of morphine dependence and inhibit the expression of abstinence syndrome in morphine-dependent animals. Locus Coeruleus [LC] and nucleus paragigantocellularis [PGi] play an important role in developing symptoms of opiate withdrawal. The objective of this study was to determine the effects of Matricaria chamomilla extract infusion into PGi on morphine withdrawal syndrome signs [MWS] of rats. Thirty male rats [weight: 250-300gr] were surgically implanted with cannula at the PGi and then tested in 2groups: saline [control group] and morphine [twice daily for 7 days]. The dose of morphine on the first and second days was 2.5 mg/kg and was doubled every day. On 7[th] day, the animals received the last injection of morphine [50mg/kg] and divided in 4 subgroups: the morphine group [which only received morphine] and three MC groups [which received 1 micro l of MC extract with the concentrations of 10, 25, 50 micro g/micro l, 5 min before naloxone administration]. In the end of the training day [7[th] day] all groups were received naloxone [5mg/kg IP] 3h after last injection of morphine and then the frequencies of withdrawal behavior [jumping, climbing] were assessed for 30 minute. Our results showed that central administration of MC extract, especially at high doses [25 micro g/micro l], significantly attenuates most signs of the morphine withdrawal syndrome. These results suggest that the injection of MC extract into the PGi may be helpful for morphine withdrawal syndrome treatment

[Effects of Matricaria chamomilla extract injection into paragigantocellularis nucleus on morphine withdrawal signs in rats]

Reports suggest that co-administration of Matricaria Chamomilla [MC] extract with morphine greatly attenuates the dependence on morphine and its injection prior to naloxan inhibits the withdrawal syndrome. Locus Ceruleus [LC] and paragigantocellularis [PGi] nuclei play a key role in appearance of withdrawal syndrome. Thus, this study was conducted to determine the effects of MC extract injection into pGi nucleus on morphine withdrawal in rats. 30 rats [Weighing 250-300gr] were divided into two groups of control [receiving saline] and morphine-treated. Following surgical implantation of cannula, morphine-treated group received morphine twice daily for 7 days. This group was classified into 4 sub-groups.The first sub-group received only morphine while the three remaining sub-groups were administed with Matricaria Chamomilla on day 7, five minutes prior to 1 microliter naloxan injection, with 10, 25, and 50 micro gr/lit, respectively. In all groups 5 mg/kg naloxan was injected 3 hours after the final injection of morphine and withdrawal behavior [jumping and climbing] was investigated for 30 minutes. The results showed that injection of all three high doses of MC extract particulary 25 microgr/microlit into PGi nuclens could significantly decline the symptoms of withdrawal syndrome. It seems that injection of MC extract into PGi nucleus could be beneficial to the treatment of morphine withdrawal syndrome in rats