Our laboratory is interested in characterizing the influence of adipose tissue hormones on avian growth and reproduction.  Adipose tissue is considered as an endocrine organ secreting a variety of hormones that are involved in the development of obesity, cardiovascular diseases, diabetes, cancer, and reproductive disorders.  Our laboratory has cloned the chicken genes that encode for two adipose tissue hormones, adiponectin and visfatin.  We are determining the factors that influence the biological functions and formation of multimeric forms of adiponectin and visfatin.  Overall, we are interested in characterizing the physiological role of adiponectin and visfatin on carbohydrate and lipid metabolism, hypothalamic control of pituitary gland function and gonadal functions.  Additionally, our laboratory is studying the neuroendocrine control of female reproduction.  We are elucidating the role of a novel neuropeptide, gonadotropin-inhibitory hormone and its receptor in controlling pituitary hormone secretion and ovarian follicular maturation. We use a variety of experimental approaches to study gene and protein expression as well as post-translational modifications at the cellular, tissue and organismal levels.

Publications

Maddineni SR, Ocón-Grove OM, Krzysik-Walker SM, Hendricks III GL, Ramachandran R (2007) Gonadotrophin-inhibitory hormone receptor expression in the chicken pituitary gland: Potential Influence of Sexual Maturation and Gonadal Steroids. Submitted to Journal of Neuroendocrinology (under revision)

Ocón-Grove OM, Krzysik-Walker SM, Maddineni S, Hendricks III GL, Ramachandran R (2007) Adiponectin and Its Receptors Are Expressed in the Chicken Testis: Influence of Sexual Maturation on Testicular AdipoR1 and AdipoR2 mRNA Abundance. Submitted to Reproduction (under revision).

Maddineni S, Ocón-Grove OM, Krzysik-Walker SM, Hendricks III GL, Ramachandran R (2007) Gonadotropin-inhibitory hormone (GnIH) receptor gene is expressed in the chicken ovary: Potential role of GnIH in follicular maturation.  Reproduction (In press)

Krzysik-Walker SM, Ocón-Grove OM, Maddineni SR, Hendricks III GL, Ramachandran R (2007) Is visfatin an adipokine or myokine? Evidence for greater visfatin expression in skeletal muscle than abdominal fat in chickens. Endocrinology (In Press)

Krzysik-Walker SM, Ocón-Grove OM, Maddineni SR, Hendricks III GL, and Ramachandran R (2007) Identification of calcitonin expression in the chicken ovary: Influence of gonadal steroids. Biology of Reproduction, 77:626-635.

Maddineni SR, Krzysik-Walker, SM, Ocón-Grove OM, Hendricks III GL, and Ramachandran R (2007) Calcitonin is expressed in the chicken pituitary gland: Influence of gonadal steroids and sexual maturation. Cell and Tissue Research, 327(3):521-528.

Ramachandran R, Ocón-Grove OM, Metzger SL (2007). Molecular cloning and tissue expression of chicken AdipoR1 and AdipoR2 complementary deoxyribonucleic acids. Domestic Animal Endocrinology, 33(1):19-31.

Ocón-Grove OM, Maddineni SR, Hendricks III GL, Elkin RG, Proudman JA, Ramachandran R (2007) Pituitary progesterone receptor expression and plasma gonadotrophin concentrations in the reproductively dysfunctional mutant restricted ovulator chicken. Domestic Animal Endocrinology, 32(3):201-215.

Proszkowiec-Weglarz M, Richards MP, Ramachandran R, McMurtry JP (2006) Characterization of the AMP-activated protein kinase pathway in chickens.  Comparative Biochemistry and Physiology, Part B 143:92-106.

Maddineni SR, Metzger SM, Ocon OM, Hendricks III GL, Ramachandran R (2005) Adiponectin gene is expressed in multiple tissues in the chicken: food deprivation influences adiponectin messenger ribonucleic acid expression. Endocrinology 146:4250-4256.

Hollon TR, Bek MJ, Lachowicz JE, Ariano MA, Mezey E, Ramachandran R, Wersinger SR, Soares-da-Silva P, Liu ZF, Grinberg A, Drago J, Young WS, 3rd, Westphal H, Jose PA, Sibley DR (2002) Mice lacking D5 dopamine receptors have increased sympathetic tone and are hypertensive. Journal of Neuroscience 22:10801-10810.

Ramachandran R, Kuenzel WJ, Proudman JA (2001) Increased proliferative activity and programmed cellular death in the turkey hen pituitary gland following interruption of incubation behavior. Biology of Reproduction 64:611-618.

Weatherly KL, Ramachandran R, Strange H, Waite KL, Storrie B, Proudman JA, Wong EA (2001) The turkey transcription factor Pit-1/GHF-1 can activate the turkey prolactin and growth hormone gene promoters in vitro but is not detectable in lactotrophs in vivo. General and Comparative Endocrinology 123:244-253.

Ramachandran R, Kuenzel WJ, Buntin JD, Proudman JA (2000) Identification of growth-hormone- and prolactin-containing neurons within the avian brain. Cell and Tissue Research 299:371-383.

Ramachandran R, Solow R, Proudman JA, Kuenzel WJ (1998) Identification of mammosomatotrophs in the turkey hen pituitary: increased abundance during hyperprolactinemia. Endocrinology 139:781-786.

Ramachandran R, Proudman JA, Kuenzel WJ (1996) Changes in pituitary somatotroph and lactotroph distribution in laying and incubating turkey hens. General and Comparative Endocrinology 104:67-75.

Ramachandran R, Proudman JA, Kuenzel WJ (1995) Changes in pituitary somatotrophs and lactotrophs associated with ovarian regression in the turkey hen (Meleagris gallopavo). Comparative Biochemistry Physiology, Part C 112:327-334.

NCBI GenBank Publications

Metzger SL, Ramachandran R (2005) Gallus gallus adiponectin receptor 1 (adipoR1) mRNA, complete CDs. Gen Bank Accession # DQ072275. http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=67782276.

Metzger SL, Ocon O, Ramachandran R (2005) Gallus gallus adiponectin receptor 2 (adipoR2) mRNA, complete CDs. Gen Bank Accession # DQ072276. http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=67782278.

Metzger SL, Maddineni SR, Ramachandran R (2005) Gallus gallus adiponectin mRNA, comple CDs.  Gen Bank Accession # AY838798. http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=61229306.