Effects of pulsed electromagnetic field with predatory stress on functional and histological index of injured-sciatic nerve in rat

Objective: To assess the effect of combination of pulsed electromagnetic fields [PEMF] with predatory stress on transected sciatic nerve regeneration in rats

Methods: In sham- operated group [SOG] the nerve was manipulated and left intact. The 10-mm rat sciatic nerve gap was created in rats. In transected group [Transected] nerve stumps were sutured to adjacent muscle and in vein graft group [VG] the gap was bridged using an inside-out vein graft. In VG/PEMF group the transected nerve was bridged using vein graft, phosphate buffered saline was administered into the graft and the whole body was exposed to PEMF. In VG/PS group the transected nerve was bridged using vein graft, phosphate buffered saline was administered into the graft and the rats underwent predatory stress [PS]. In VG/PEMF/PS group the transected nerve was bridged using vein graft, phosphate buffered saline was administered into the graft, the whole body was exposed to PEMF and the rats underwent predatory stress. The regenerated nerve fibers were studied within 12 weeks after surgery

Results: Functional, gastrocnemius muscle mass findings and morphometric indices confirmed faster recovery of regenerated axons in VG/PEMF and VG/PEMF/PS groups compared to those in the other groups [p=0.001]. The whole body exposure to PEMF improved functional recovery. Predatory stress did not affect nerve regeneration in the animals undergone predatory stress [p=0.343]

Conclusion: Pulsed electromagnetic fields could be considered as an effective, safe and tolerable treatment for peripheral nerve repair in clinical practice

Neuroplasticity changes of rat brain by musical stimuli during fetal period

Fetal development of the central nervous system is an important and sensitive stage which is affected by many external and internal stimuli. This study aimed to investigate effect of musical stimuli on fetal rat brain. In this experimental study, twelve female Wistar rats were selected and evenly assigned to control and musical groups. The females were mated with a male rat of the same genotype. Musical group was exposed to classic music with 60 dB power for 90 minutes twice per day from 2[nd] to 20[th] day of gestation. The control rats were handled similar to the musical group, but were not exposed to music. Before parturition, all the dams were anesthetized, and their blood samples were obtained and used for corticosterone [COS] measurement. They were transcardially perfused by electron microscope [EM] fixative agent. The fetal brains were extracted intact and used for slice preparation. Horizontal slices were made for electron microscope preparation, and images were taken and analyzed in terms of cell density and morphological changes. EM observation indicated significant morphological difference in cellular and intercellular spaces between the two groups. Music-treated fetuses had significantly higher cell density in parietal cortex and music-treated dams had lower COS level. It was concluded that prenatal music would have a great impact on neuroplasticity of fetal rat brain, at least indirectly. Although the rat fetuses cannot hear until birth, music-induced reduction in COS blood level of dams might be the reason for neuroplasticity of fetal brain

Time dependent antinociceptive effects of morphine and tramadol in the hot plate test: using different methods of drug administration in female rats

Morphine and tramadol which have analgesic effects can be administered acutely or chronically. This study tried to investigate the effect of these drugs at various times by using different methods of administration [intraperitoneal, oral, acute and chronic]. Sixty adult female rats were divided into six groups. They received saline, morphine or tramadol [20 to 125 mg/Kg] daily for 15 days. A hot plate test was performed for the rats at the 1[st], 8[th] and 15[th] days. After drug withdrawal, the hot plate test was repeated at the 17[th], 19[th], and 22[nd] days. There was a significant correlation between the day, drug, group, and their interaction [P<0.001]. At 1[st] day [d1], both morphine, and tramadol caused an increase in the hot plate time comparing to the saline groups [P<0.001], while there was no correlation between drug administration methods of morphine and/or tramadol. At the 8[th] day [d8], morphine and tramadol led to the most powerful analgesic effect comparing to the other experimental days [P<0.001]. At the 15[th] day [d15], their effects diminished comparing to the d8. After drug withdrawal, analgesic effect of morphine, and tramadol disappeared. It can be concluded that the analgesic effect of morphine and tramadol increases with the repeated use of them. Thereafter, it may gradually decrease and reach to a level compatible to d1. The present data also indicated that although the analgesic effect of morphine and tramadol is dose-and-time dependent, but chronic exposure to them may not lead to altered nociceptive responses later in life

[Comparison of the effects of chronic administration of morphine and tramadol in infancy on acute pentylenetetrazol-induced seizure in prepubertal rats]

It is demonstrated that morphine and tramadol affects seizure but the mode of action of these drugs on seizure has not been compared yet with increasing of age. The aim of this study was to compare the impact of exposure to these drugs on Pentylenetetrazol-induced seizure in immature rat. Male neonate rats were randomly chosen and divided into three groups namely Saline [n=21], Morphine [n=12] and Tramadol [n=13]. On postnatal days 8-14, Saline group received normal saline and two other groups received morphine and tramadol with additive doses, respectively. On postnatal days 22-28, the saline treated rats divided into three subgroups and received saline [n=8], morphine [n=8] or tramadol [n=5]. Morphine treated rats received saline or morphine [each n=6], and tramadol treated rats received saline [n=7] or tramadol [n=6]. At postnatal day 29, they were evaluated for PTZ-induced seizure. Number of tonic-clonic seizure was increased in all groups compared with control and tramadol+saline groups [P<0.05]. Duration of tonic-clonic seizure was decreased in tramadol+saline group compared with other tramadol groups [P<0.05]. Latency of tonic-clonic seizurewas decreased in tramadol+saline group compared with control rats [P<0.05], But it was increased in saline+tramadol group compared with other groups except to saline group [P<0.05]. Latency of myoclonic contractions in saline+morphine and saline+tramadol groups was lower than in control rats [P<0.05]. Similar age-related changes may occur inchronic exposure to morphine and tramadol in the neonatal period which leads to an increase in severity of seizures in rats on postnatal days 22-28. The effect of morphine and tramadol does not show any significant difference

[Leptin levels in breast milk of mother bearing girls and boys]

Clinical studies indicate that females have higher blood leptin levels when compared with the male gender, however to date there is no available report on the impact of offspring gender on maternal milk leptin [ML] levels. Therefore, this study was designed to investigate the effect of child gender on ML levels. A cross-sectional study was carried out across Urmia city health centers, Iran. 115 mothers were selected across a wide range of population. A questioner was designed with respect to infant gender, age and weight. Questioners were filled by all applicants and a 10 ml breast milk sample was taken for further analysis of ML levels and specific gravity [SG] determination. Mothers were divided into 5 different groups based on offspring's age. Maternal ML levels were significantly different according to offspring gender. ML levels were significantly higher in mothers with girls than mothers who have given birth to baby boy. However, there was no significant difference between ML levels with respect to infant age. SG level was found to be different among all groups and no significant correlation was found between SG and ML levels of all applicants. It was concluded that maternal ML levels varies with respect to the offspring gender. ML levels in infant girls are higher than that of the boy; however the mechanism of action is still unclear. A normal reduction in salt and water retention that occurred postpartum may cause slight elevation in SG of the breast milk

Modulation of basal glutamatergic transmission by nicotinic acetylcholine receptors in rat hippocampal slices

Nicotinic acetylcholine receptors [nAChRs] regulate epileptiform activity and produce a sustained proepileptogenic action within the hippocampal slices. In the present study, we investigated the effect of nAChRs on evoked glutamatergic synaptic transmission in area CA3 and CA1 of rat hippocampal slices to identify possible excitatory circuits through which activation of nAChRs produce their pro-epileptogenic effects. Hippocampal slices [400 micro m thick] prepared in vitro from male Wistar rats [3-5 weeks], using standard procedures. Following 1 hr equilibration in artificial cerebrospinal fluid [ACSF], slices transferred to an interface recording chamber. Stimulatory electrodes placed within the hilus or Schaffer-collateral pathways and extracellular field recordings made in the stratum radiatum of the CA1 and CA3 regions to investigate evoked synaptic responses. Bath application of the selective nAChR agonist dimethylphenyl-piperanzinium [DMPP, 30 micro M] resulted in a sustained and reversible enhancement of glutamate afferent evoked fEPSP amplitude by 15.7 +/- 5.1% [mean +/- SEM; n = 8 of 12] in the CA3 region of the hippocampus but not in the CA1 [-5.25 +/- 8.3%, mean +/- SEM; n = 5]. Activation of nAChRs may produce pro-epileptogenic actions in part through regulating glutamatergic circuits. Difference in nAChR regulation is also evident between different regions of hippocampus