Affiliations: Department of Animal and Dairy Science, University of
Georgia, Athens, GA, USA | Department of Foods and Nutrition, University of
Georgia, Athens GA, USA
Note: [] Address for correspondence: Dr. Clifton A. Baile, 444 Animal
Science Complex, University of Georgia, Athens GA 30602-2771, USA. Tel.: +1 706
542 4094; Fax: +1 706 542 7925; E-mail: cbaile@uga.edu
Abstract: Ciliary neurotrophic factor (CNTF) and leptin are cytokine-like%
hormones and act on their corresponding receptors in the hypothalamic arcuate
nucleus (ARC). The present study was designed to assess effects of
intracerebroventricular (ICV) injection of leptin and CNTF on gene expression
in micropunched hypothalamic arcuate nucleus-median eminence (ARC-ME) complex
samples from rats. Male Sprague Dawley rats were implanted with lateral
cerebroventricular cannulas for administration of control, 10 μg/d leptin
or 5 μg/d CNTF for four days. Real-time Taqman™ RT-PCR was
used to quantitatively compare the mRNA levels of selected genes in the ARC-ME
complex. Leptin and CNTF increased ARC-ME mRNA levels of signal transducer and
activator of transcription 3 (STAT3) by 64.5 and 124.7% (p < 0.01),
suppressor of cytokine signaling 3 (SOCS3) by 258.9 and 1063.9% (p <
0.01), cocaine and amphetamine regulated transcript (CART) by 102.7 and
123.1% (p < 0.01), and proopiomelanocortin (POMC2) by 374.1 and
264.9% (p < 0.01), respectively. Leptin increased growth hormone
releasing hormone (GHRH) by 309.9% (p < 0.01), while CNTF increased
janus kinase 2 (JAK2) mRNA by 31.7% (p < 0.01) and decreased
gonadotropin releasing hormone 1 (GNRH1) by 59.7% (p < 0.01), mitogen
activated protein kinase 1 (MAPK1) by 19.4% (p < 0.05) and tyrosine
hydroxylase (TH) by 74.5% (p < 0.05). Significant reduction in daily
food intake and body weights by both the treatments was observed. Also,
decrease in weights of fat pads was concomitant with lowered serum insulin and
leptin levels. Our findings show that leptin and CNTF engage both convergent
and divergent pathways involved in feeding, cellular signaling, inflammation,
and other related regulatory systems.
