A follow-up set of experiments with newly born Ob/Ob KO mice, (–/–), heterozygous mice (–/+) and homozygous wildtype (+/+) mice was evaluated over an 18-week interval (see Figure 1B). It is quite apparent that the Ob/Ob (–/–) KO mice that had an absence of leptin were unable to control their body weight. By 18 weeks the heterozygous mice and wildtype mice weighed ~500 grams, while the KO mice weighed ~750 grams or 150% of the wildtype. Thus in the presence of leptin there was a marked reduction in obesity. In addition, leptin reduced the food intake and increased the ob/ob mouse expenditure of metabolic energy.

Fig1. Importance of leptin and its gene in regulating the body’s energy balance. (A) Knock-out of the leptin gene. The obese mouse on the left has a knock-out mutation on chromosome 7 creating a (–/–) phenotype which has altered the pattern of fat deposition in its body. The mouse on the right has a normal (+/+) phenotype. The “obesity” gene is believed to act in collaboration with other genes that regulate the body’s energy balance. Mice with the mutation grow 35–50% fatter by middle age than a normal mouse, despite eating a low-fat diet. [The mice were photographed at Oak Ridge National Laboratory in Tennessee.] (B) Effect of absence of leptin on mouse body weight. Body weight assessment over 18 weeks for leptin (–/–), (+/–), and (+/ +) male rats. In the knock-out –/– leptin animal (red line), the absence of leptin results in an uncontrolled appetite, which over 18 weeks leads to obesity and an abnormal intermediary metabolism. In the heterozygous (+/–) animals (blue line), and wild type (+/+) animals (brown line), there is a marked reduction of the obesity due to the presence of leptin. These genetically manipulated animals have been useful in studying diabetes, atherosclerosis, and high blood pressure associated with high serum cholesterol levels. (C) Effect of absence of leptin on regulation of serum glucose levels. Glucose tolerance test in leptin knock out (–/–) and wild type (+/+) rats. Animals were fasted for 16 hours prior to an intravenous injection of a bolus of glucose. Then their blood glucose levels were determined at 15-minute intervals over 120 minutes. In the leptin (–/–) animals, serum glucose levels remained elevated in comparison to the (+/+) wild type rats which can produce adequate amounts of leptin to control the blood glucose levels. The data shown in panels B and C were provided by Sage Labs. See the following URL: http://www.sageresearchmodels.com/research-models/ knockout-rats/leptin-knockout-rat-%E2%80%94-kilorat%E2%84%A2.

In a follow-up experiment, a glucose tolerance test was carried out in Ob/Ob (–/–) KO mice and in Ob/ Ob (+/+) wildtype mice. A glucose tolerance test is a standard clinical assay where glucose is given orally (humans) or intraperitoneally (mice) and sequential blood samples are taken over 1–2 hours so as to determine how quickly glucose is cleared from the blood compartment (see Figure 1C). In this experiment the consequences of the presence and absence of leptin on the rapid lowering of blood glucose levels was determined. In the Ob/Ob (–/–) mice the high levels of blood glucose were reduced much more slowly in the absence of leptin than in the Ob/Ob (+/+) mice that had normal access to leptin. This clearly demonstrates the modulation of blood glucose levels by the prevailing levels of leptin.

اخر الاخبار

اخبار العتبة العباسية المقدسة

إيذانًا ببدء فعاليات حفل التكليف المركزي.. انطلاق مسير التلميذات في مجمع أبي الفضل العباس (عليه السلام)

بدء توافد التلميذات المشاركات في فعاليات حفل التكليف الشرعي ضمن مشروع الورود الفاطمية

قسم الشؤون الفكرية يقدم محاضرة حول الأخلاق الإدارية في بيئة العمل لوفد من ذي قار

العتبة العباسية المقدسة تقيم مهرجان (وشاح الطهر) لتكريم الطالبات المرتديات للعباءة العراقية في المثنى

المزيد

الآخبار الصحية

عوامل تضعف القدرات الإدراكية لدى الإنسان

طريقة جديدة لتجديد خلايا الدماغ

دراسة بريطانية: الأطعمة النباتية عالية الجودة تقلل خطر فشل القلب

7 أطعمة يومية "تسمم" جسمك بالبلاستيك دون أن تشعر

المزيد

الآخبار التكنلوجية

اكتشاف أثري في أوريغون الأمريكية قد يعيد كتابة تاريخ البشرية

اكتشاف كائن بحري مدرع بلسان "حديدي" في بحر اليابان

نظام كوكبي "مقلوب" يحير علماء الفلك

بسبب الذكاء الاصطناعي.. هذه الوظائف "ستختفي" بعد أشهر قليلة ؟!

المزيد

مواضيع ذات صلة

Engineered CRISPR–Cas9 Systems Allow Precise Genome Editing

Plasmid Expression Vectors Can Be Designed for Use in Animal Cells

Engineering Antibody Synthesis in Bacteria

Heritable Genome Editing

Challenges to in Vivo Editing of Hematopoietic Stem Cells

EX Vivo Manufacturing of Therapeutic Cells

Using Engineered Nucleases to Initiate the Genome Editing Process

Base Editing

Double-stranded DNA breaks: the basis of nuclease-based genome editing

Plaque and Colony Hybridization for Clone Identification

Cloning from RNA

Plasmid Vectors