Alper KARAKAŞ, Hamit COŞKUN, Fevziye Umut KIZILKAYA

Memory-enhancing effects of the leptin hormone in Wistar albino rats: sex and generation differences

Leptin is a hormone secreted by adipose tissue that informs the brain about the fat stores of the body. In this study, we examined the effects of timed leptin injections on spatial memory performances of adult and juvenile male and female Wistar rats with the Morris water maze test. We applied the injections and conducted the training trials for 4 days. On the fifth day after leptin injections, the experiments were performed. The activities were recorded and analyzed with the Noldus Ethovision Animal Video Tracking System. The results show that the spatial memory performance of the rats was improved by the leptin injections since they shortened the latency to find the platform and elongated the time spent in the correct quadrant. The age of the rats was found to be important since the adults found the platform faster than the juveniles. There was an interaction effect between sex and generation in all parameters examined except for the time spent in the correct quadrant. The results of the present study suggest that leptin administration via timed injections strengthens spatial memory in Wistar albino rats, but this effect depends upon the sex and the generation of the rats.

Anahtar Kelimeler:

Key words: Leptin, Morris water maze, spatial memory

Memory-enhancing effects of the leptin hormone in Wistar albino rats: sex and generation differences

Keywords:

Key words: Leptin, Morris water maze, spatial memory,

PDF

___

Zhang Y, Proenca R, Maffei M et al. Positional cloning of the mouse obese gene and its human homologue. Nature 372: 425– 432, 1994.
Commins SP, Marsh DJ, Thomas SA et al. Norepinephrine is required for leptin effects on gene expression in brown and white adipose tissue. Endocrinology 140: 4772–4778, 1999.
Sivitz WI, Fink BD, Morgan DA et al. Sympathetic inhibition, leptin, and uncoupling protein subtype expression in normal fasting rats. Am J Physiol 277: E668–E677, 1999.
Ahima RS, Prabakaran D, Mantzoros C et al. Role of leptin in the neuroendocrine response to fasting. Nature 382: 250–252, 19 Ahima RS, Prabakaran D, Flier JS. Postnatal leptin range and regulation of circadian rhythm of leptin by feeding. Implications for energy homeostasis and neuroendocrine function. J Clin Invest 101: 1020–1027, 1998.
Pickavance L, Tadayyon M, Williams G et al. Lactation suppresses diurnal rhythm of serum leptin. Biochem Bioph Res Co 248: 196–199, 1998.
Shimokawa I, Higami Y. A role for leptin in the antiaging action of dietary restriction: a hypothesis. Aging-Clin Exp Res 11: 380–382, 1999.
Omura Y, Hori B, Shiraishi T et al. Leptin facilitates learning and memory performance and enhances hippocampal CA1 long-term potentiation and CaMK II phosphorylation in rats. Peptides 2738–2749, 2006.
Li XL, Aou S, Oomura Y et al. Impairment of long-term potentiation and spatial memory in leptin receptor-deficient rodents. Neuroscience 3: 607–615, 2002.
Maffei M, Halaa J, Ravussin E et al. Leptin levels in human and rodent: measurement of plasma leptin and ob RNA in obese and weight reduced subjects. Nat Med 11: 1155–1161, 1995.
Castracane VD, Kraemer RR, Franken MA et al. Serum leptin concentration in women: effect of age, obesity and estrogen administration. Fertil Steril 70: 472–477, 1998.
Rosenbaum M, Leibel R. The role of leptin in human physiology. New Engl J Med 341: 913–915, 1999.
Montague CT, Prins JB, Sanders L et al. Depot- and sex-specific differences in human leptin mRNA expression: implications for the control of regional fat distribution. Diabetes 46: 342– 347, 1997.
Van Harmelen V, Reynisdottir S, Eriksson P et al. Leptin secretion from subcutaneous and visceral adipose tissue in women. Diabetes 47: 913–917, 1998.
Shimizu H, Ohtani K, Tsuchiya T et al. Leptin stimulates insulin secretion and synthesis in HIT-T 15 cells. Peptides 8: 1263–1266, 1997.
Mantzoros CS, Flier JS, Rogol AD. A longitudinal assessment of hormonal and physical alterations during normal puberty in boys, V. Rising leptin level may signal the onset of puberty. J Clin Endocr Metab 82: 1066–1070, 1997.
Elbers JM, Asscheman H, Seidell JC et al. Reversal of the sex difference in serum leptin levels upon cross-sex hormone administration in transsexuals. J Clin Endocr Metab 82: 3267– 3270, 1997.
Horlick MB, Rosenbaum M, Nicolson M et al. Effect of puberty on the relationship between circulating leptin and body composition. J Clin Endocr Metab 85: 2509–2518, 2000.
Considine RV, Sinha MK, Heman ML et al. Serum immunoreactive-leptin concentrations in normal-weight and obese humans. N Engl J Med 334: 292–295, 1996.
Ruhl CE, Everhart JE. Leptin concentrations in the United States: relations with demographic and anthropometric measures. Am J Clin Nutr 74: 295–301, 2001.
Li AJ, Katafuchi T, Od S et al. Interleukin-6 inhibits long-term potentiation in rat hippocampal slices. Brain Res 748: 30–38, 19 Hooge RD, De Deyn PP. Applications of the Morris water maze in the study of learning and memory. Brain Res Rev 36: 60–90, 200 Ohta R, Shigemura N, Sasamoto K et al. Conditioned taste aversion learning in leptin receptor deficient db/db mice. Neurobiol Learn Mem 80: 105–112, 2003.
Bear MF, Malenka RC. Synaptic plasticity: LTP and LTD. Curr Opin Neurobiol 4: 389–399, 1994.
Malenka RC. Synaptic plasticity in the hippocampus: LTP and LTD. Cell 78: 535–538, 1994.
Malenka RC, Nicoll RA. Long-term potentiation–a decade of progress? Science 285: 1870–1874, 1999.
Bliss TV, Collingridge GL. A synaptic model of memory: longterm potentiation in the hippocampus. Nature 361: 31–39, 19 Asakawa A, Inui A, Inui T et al. Leptin treatment ameliorate anxiety in ob/ob obese mice. J Diabetes Complicat 17: 105– 107, 2003.
Devaskar SU, Ollesch C, Rajakumar RA et al. Developmental changes in obese gene expression and circulating leptin peptide concentrations. Biochem Bioph Res Co 238: 44–47, 1997.
Ahima RS, Bjorbaek C, Osel S et al., Regulation of neuronal and glial proteins by leptin: implications for brain development. Endocrinology 140: 2755–2762, 1999.
Calapai G, Corica F, Allegra A et al. Effects of intracerebroventricular leptin administration on food intake, body weight gain and diencephalic nitric oxide synthase activity in the mouse. Brit J Pharmco 79: 800–802, 1998.
Bates SH, Myers MG. The role of leptin receptor signaling in feeding and neuroendocrine function. Trends Endocrin Met 14: 447–452, 2003.
Gündüz B, Karakaş A. The effects of leptin hormone on locomotor activity in Syrian hamsters (Mesocricetus auratus). Turk J Biol 35: 727–734, 2011.
Sutcliffe JS, Marshall KM, Neill JC. Influence of gender on working and spatial memory in the novel object recognition task in the rat. Behav Brain Res 177: 117–125, 2007.
McGivern RF, Huston JP, Byrd D et al. Sex differences in visual recognition memory: support for a sex-related difference in attention in adults and children. Brain Cognition 34: 323–333, 19 Meyers-Levy J, Cafferata P, Tybout AM. Gender differences in information processing: a selectivity interpretation. In: Cafferata P, Tybout AM. eds. Cognitive and Affective Responses to Advertising. Lexington Books; 1989: p. 30.
Silverman I, Eals M, Barkow JH et al. Sex differences in spatial abilities: evolutionary theory and data. In: Tooby J. ed. The Adapted Mind. Oxford University Press; 1992: pp. 533–549.
Eals M, Silverman I. The hunter-gatherer theory of spatial sex differences: proximate factors mediating the female advantage in recall of object arrays. Ethol Sociobiol 15: 95–105, 1994.
Frye C. Associated decrements in water maze task are limited to acquisition. Physiol Behav 57: 5–14, 1995.
Luine VN, Richards ST, Wu VY et al. Estradiol enhances learning and memory in a spatial memory task and affects levels of monoaminergic neurotransmitters. Horm Behav 2: 149–162, 1998.
Warren SG, Juraska JM. Sex differences and estropausal phase effects on water maze performance in aged rats. Neurobiol Learn Mem 3: 229–240, 2000.
Wide JK, Hanratty K, Galea LAM . High level estradiol impairs and low level estradiol facilitates non-spatial working memory. Behav Brain Res 1: 45–53, 2004
Daniel JM. Effects of estrogen on cognition: what have we learned from basic research? J Neuroendocrinol 10: 787–795, 200