Leptin and neuroendocrine regulation

Insan ob gen kromozomu tarafından yag dokusunda sentezlenen bir hormon olan leptin istahı ve enerji harcamasını düzenler. Obez kisilerde serum leptin düzeyleri belirgin olarak yüksektir. Ob gen defekti olan ob/ob tipi farelerde, leptinin yeterince üretilememesi nedeniyle yag depolanması fazladır. Obez kadın ve erkeklerde leptin düzeyi ile vücut kitle indeksi arasında pozitif bir iliski gösterilmistir. Leptin reprodüktif fonksiyonlarda da görevlidir. Infertil ve gonadotropin seviyesi düsük ob/ob farelere leptin enjekte edildiginde, uterus ve overlerinin agırlıkları ve overlerdeki folikül sayısı artarak fertilitenin korunması saglanmıstır. Normal disi farelere leptin uygulandıgında ise pubertenin hızlandıgı gözlenmistir. Diger yandan leptin osteoblastik hücre büyümesinde ve kemik mineralizasyonunda rol oynayabilir. Leptin ayrıca nöropetid Y'yi inhibe edip gonadotropinlerin ve seks steroidlerinin sentezini stimüle eder. Uterin miyomlarda leptin geninin ekspresyonu gösterilirken saglıklı insanlardan alınan miyometriumda gösterilememistir, bu nedenle uterin miyom etyopatogenezinde leptinin rolü olabilecegi savunulmaktadır. Sonuç olarak istahı ve enerji harcanmasını regüle eden leptin reprodüktif ve nöroendokrin sistemde de önemli rol oynamaktadır.Leptin, the product of the ob gene, is produced exclusively by the adipose tissue and regulates energy intake and expenditure. Obese individuals have considerably higher serum leptin concentrations. In ob/ob mice, the fat deposition is increased as a result of insufficient production of leptin. In obese women and men, there is correlation between serum leptin concentrations and body mass index. Leptin appears to influence various reproductive functions. Injecting leptin into ob/ob mice that are infertile and with low levels of gonadotropin increases the weight of the uterus and ovaries and the number of follicles, resulting in restoration of fertility. Administering leptin treatment to normal female mice accelerates puberty. Leptin may be of importance for osteoblastic cell growth and bone mineralization. Leptin may also be expected to stimulate gonadotropin and sex- steroid synthesis and secretion through inhibition of Neuropeptide Y. It has been reported that leptin was expressed in several uterine myomas but not in normal myometrium, so leptin may have a role in the etiopathogenesis in uterine leiomyoma. In conclusion, leptin, regulating energy intake and expenditure also has regulatory effects on reproductive and neuro-endocrine systems

The sympathetic skin response habituation in sedentary subjects and sportsmen

The aim of the present study was to investigate the habituation rates of the sympathetic skin response (SSR) in sedentary subjects and trained sportsmen. A total of 52 voluntary male students (30 sedentary subjects and 22 trained sportsmen) participated in the experiment. SSR was recorded with the contralateral electrical stimulation of the ulnar nerve (of the upper extremities). In order to initiate the SSRs, 16 square-wave consecutive electrical shock stimuli were presented to each subject over the left ulnar nerve. In 52 subjects, 16 stimuli were applied at random time intervals (20-50 s). In sedentary subjects, the mean amplitude of the SSRs decreased from 4.83 +/- 0.36 mV at the first stimulus, to 0.80 +/- 0.12 mV at the 16th stimulus. In trained sportsmen, the mean amplitude of the SSRs decreased from 3.95 +/- 0.51 mV at the first stimulus, to 0.80 +/- 0.17 mV at the 16th stimulus. In the sedentary subjects, at the S1-S9 stimuli, the mean amplitudes of SSRs were higher than those of trained sportsmen. Depending upon these findings we can say that the trained sportsmen showed a more rapid habituation than sedentary subjects. In these processes, changes of amplitude and latency values reflect changes in amount of neuronal activation. Amplitude reflects the amount of neuronal activation, which is concerned with number of neuronal populations. Neuroplasticity, known as the habituation of the brain, is the adaptation of autonomic nervous system, which can be reflected by SSRs

Delayed habituation in Behcet's disease

WOS: 000254671200006PubMed: 18310833Background: The autonomic nervous system in Behcet's patients may be affected due to various reasons. This entity may be detected with the measurement of the electrodermal activities, heart rate variability and pupillometric methods. Habituation is one of the implicit forms of learning and memory and the loss of habituation can reveal pathological changes in the synaptic regions. Aim: To determine whether there is a functional decrease in the synaptic effectiveness (habituation) of the pathways to sympathetic neurons that had been repeatedly activated in Behcet's. Materials and Methods: Twelve patients with Behcet's disease and 12 healthy controls were included in the study. Sympathetic skin potential (SSP) records were taken at normal room temperature in a quiet place within a Faraday cage. Sixteen square wave single shock impulses (duration: 1200 mu s, strength: 5 mA) were applied on each case. Results: After the 1(st) stimulus, the SSP amplitudes were lower in the patients compared to the controls (P 0.001, t value = 7.69). There was no significant differences among the SSP amplitudes after the 13(th) impulse in the patients (P>0.05). Whereas there was no significant differences among the SSP amplitudes after the 9(th) impulse in the controls (P>0.05). The habituation rate of the SSP after consecutive impulses was slowest in the patients compared to controls (P<0.001, t value = 12.39). Conclusions: There is a delayed habituation in Behcet's disease and that may due to pathologic changes with vasculitis through their peripheral nerves

Evaluation Of Effects Of T And N Type Calcium Channel Blockers On The Electroencephalogram Recordings In Wistar Albino Glaxo/Rij Rats, An Absence Epilepsy Model

OBJECTIVES: It is suggested that excessive calcium entry into neurons is the main triggering event in the initiation of epileptic discharges. We aimed to investigate the role of T and N type calcium channels in absence epilepsy experimental model. MATERIALS AND METHODS: Wistar Albino Glaxo/Rij (WAG/Rij) rats (12–16 weeks old) were randomly allocated into four groups; sham, mibefradil (T type calcium channel blocker), w-Conotoxin MVIIA (N type calcium channel blocker), and mibefradil + w-Conotoxin MVIIA. Beta, alpha, theta, and delta wave ratios of EEG recordings and frequency and duration of spike wave discharges (SWDs) were analyzed and compared between groups. RESULTS: Beta and delta recording ratios in 1 μM/5 μl mibefradil group was significantly different from basal and other dose-injected groups. Beta, alpha, and theta recordings in 0.2 μM/5 μl w-Conotoxin MVIIA group was significantly different from basal and other dose-injected groups. In w-Conotoxin MVIIA after mibefradil group, beta, alpha, and theta recording ratios were significantly different from basal and mibefradil group. Mibefradil and w-Conotoxin MVIIA significantly decreased the frequency and duration of SWDs. The decrease of frequency and duration of SWDs in mibefradil group was significantly different from w-Conotoxin MVIIA group. The frequency and duration of SWDs significantly decreased in w-Conotoxin MVIIA after mibefradil group compared with basal, mibefradil, and w-Conotoxin MVIIA groups. CONCLUSIONS: We concluded that both T and L type calcium channels play activator roles in SWDs and have positive effects on frequency and duration of these discharges. These results are related with their central effects more than peripheral effects