Physiology Commons^™

Development And Validation Of A Predictive Model Of Acute Glucose Response To Exercise In Individuals With Type 2 Diabetes, Bryan S. Gibson, Sheri R. Colberg, Paul Poirier, Denise Maria Martins Vancea, Jason Jones, Robin Marcus

Human Movement Sciences & Special Education Faculty Publications

Background: Our purpose was to develop and test a predictive model of the acute glucose response to exercise in individuals with type 2 diabetes.

Design and methods: Data from three previous exercise studies (56 subjects, 488 exercise sessions) were combined and used as a development dataset. A mixed-effects Least Absolute Shrinkage Selection Operator (LASSO) was used to select predictors among 12 potential predictors. Tests of the relative importance of each predictor were conducted using the Lindemann Merenda and Gold (LMG) algorithm. Model structure was tested using likelihood ratio tests. Model accuracy in the development dataset was assessed by leave-one-out cross-validation. …

Heifer Estrous Cycle Stage Impacts Luteinizing And Growth Hormone Response To Kisspeptin, Brian K. Whitlock, Joseph A. Daniel, Robyn R. Wilborn, Barbara P. Steele, James L. Sartin

Animal Science Publications and Other Works

The reproductive neuropeptide, kisspeptin (KP), may have a role in regulation of growth hormone (GH) secretion. Expression of KP and its receptor (Kiss1r) are developmentally and hormonally regulated. This study was conducted to determine the effects of KP on plasma concentrations of luteinizing hormone (LH) and GH in pubertal heifers during different functional reproductive stages. Heifers received a single injection of KP (100 pmole / kg) or saline intravenously during proestrus, estrus, and diestrus, and serial blood samples were collected for 3 hours to determine the response of both LH and GH after treatment. Mean concentrations of LH were increased …

Effect Of Kisspeptin On Regulation Of Growth Hormone, Brian K. Whitlock, Joseph A. Daniel, Robyn R. Wilborn, Herris S. Maxwell, Barbara P. Steele, James L. Sartin

Animal Science Publications and Other Works

Kisspeptin ( KP ), a neuroendocrine regulator of reproduction, is hypothesized to be an integrator of metabolism and hormones critical to the regulation of reproduction. Lactation is associated with enhanced growth hormone (GH) responsiveness and reduced fertility. Our study was designed to determine the effects of lactation on KP-stimulated GH and luteinizing hormone (LH) secretion. Five non-lactating and five lactating dairy cows were used in the study. Experiments were conducted with lactating cows at weeks 1, 5 and 11 after parturition. The experimental treatments ( saline and KP [100 and 400 pmol / kg body weight]) were given intravenously and …

The Effect Of Kisspeptin Receptor Agonist (Ftm080) On Luteinizing Hormone In Sheep, Brian K. Whitlock, Joseph A. Daniel, Maria Hes, Barbara P. Steele, James L. Sartin, S. Oishi, N. Fujii

Animal Science Publications and Other Works

Kisspeptin receptor (Kiss1r) agonists with increased half-life and similar efficacy to kisspeptin (KP) in vitro potentially may provide beneficial applications in breeding management of many species. However, many of these agonists have not been tested in vivo. This study was designed to test the effect of a Kiss1r agonist (FTM080) on luteinizing hormone (LH) in vivo. Sheep were treated with FTM080 (500 pmol/kg BW) or sterile water in a 2-ml bolus via the jugular cannula. Serial blood samples were collected every 15-min before (1 hr) and after (1 hr) treatment. Intravenous (IV) injection of FTM080 increased (P < 0.05) LH plasma concentrations through the 45-min sample following treatment. Moreover, the area under the curve of LH in the period from 0 to 60-min following FTM080 treatment was also increased (P < 0.05). These data provide evidence to suggest that FTM080 stimulates the gonadotropic axis of ruminants in vivo.

Reciprocal Regulation Of Trek-1 Channels By Arachidonic Acid And Crh In Mouse Corticotropes, Andy K. Lee, James L. Smart, Marcelo Rubinstein, Malcolm J. Low, Amy Tse

Faculty Publications - Department of Biological & Molecular Science

Arachidonic acid (AA) is generated in the anterior pituitary gland upon stimulation by the ACTH secretagogue, CRH. Using the patch clamp technique,we examined the action of AA on the excitability of single pituitary corticotropes obtained from a transgenic mouse strain that expresses the enhanced green fluorescent protein driven by the proopiomelanocortin promoter. CRH evoked depolarization, but AA caused hyperpolarization. Under voltage clamp condition, AA caused a rapid inhibition of the delayed rectifier K current and then increased a background K current. Inhibition of AA metabolism did not prevent the activation of the K current by AA, suggesting a direct action …

Flank Gland-Secreted Putative Chemosignals Pertaining To Photoperiod, Endocrine States, And Sociosexual Behavior In Golden Hamsters, Ying-Juan Liu, Da-Wei Wang, Lixing Sun, Jin-Hua Zhang, Jian-Xu Zhang

All Faculty Scholarship for the College of the Sciences

Behavioral studies have shown that flank glands are involved in chemical communication in golden hamsters Mesocricetus auratus but little chemical analysis has been conducted on volatiles arising from these glands. Using gas chromatography- mass spectrometry, we detected compounds from the flank glands of males, only eight of which were also produced in females. Based on these chemical data we performed a number of further experiments. By manipulating light we found that males exposed to short-photoperiods developed smaller flank glands than those exposed to long-photoperiods. Six flank gland volatiles reduced in relative abundance, which possibly coded for reproductive status of males …

Selected Hormonal And Neurotransmitter Mechanisms Regulating, James L. Sartin, Joseph A. Daniel, Brian K. Whitlock, Robyn R. Wilborn

Faculty Publications and Other Works -- Large Animal Clinical Sciences

Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and realtime PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several …

Changes In Plasma Concentrations Of Leptin In Ewes During Pregnancy, Joseph A. Daniel, A B. Milam, M E. Gafnea, Brian K. Whitlock, D H. Keisler

Animal Science Publications and Other Works

Previous research has demonstrated circulating concentrations of leptin increase in ewes during mid pregnancy then decline in late pregnancy and early lactation. The objective of this study was to more narrowly define the timing of changes in circulating concentrations of leptin with pregnancy in ewes. Katahdin ewes (n= 19) located at latitude 34.275 and longitude -85.183 (Mount Berry, GA) were utilized. Blood samples were collected weekly via jugular veinpuncture beginning immediately before ram exposure on September 23 and continuing until 4 weeks post-lambing. Ewes were exposed to a ram fitted with a marking harness for a 63 day breeding season. …

Effect Of Leukemia Inhibitory Factor On Feed Intake And Body Temperature In Sheep, James L. Sartin, D L. Marks, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele

Animal Science Publications and Other Works

Leukemia inhibitory factor (LIF) has been suggested to function as a potent inhibitor of feed intake in rodents. These studies were designed to determine whether LIF was found in the ovine hypothalamus and whether LIF inhibited feed intake in sheep. Sheep hypothalami were used to clone LIF to indicate presence of the gene in the hypothalamus. The sequence was similar to published data. Another group of sheep were provided intraventricular (ICV) cannulas and injected with doses of LIF at 250, 500, 1000 and 2500 ng per sheep, ICV. Feed intake was inhibited by the 1000 and 2500 ng dose (trt, …

Changes In Plasma Concentrations Of Growth Hormone And Luteinizing Hormone In Ewes Following Central And Peripheral Treatment With Kisspeptin, Brian K. Whitlock, Joseph A. Daniel, Barbara P. Steele, James L. Sartin

Animal Science Publications and Other Works

Kisspeptin (KP), a neuroendocrine regulator of gonadotropin releasing hormone, has been hypothesized as an integrator of nutrition and hormones critical to metabolism and regulation of reproduction. Recent evidence suggests growth hormone (GH) secretion may be influenced by KP. The objective of this study was to determine if the GH stimulatory effect of KP is due to actions on the hypothalamus or anterior pituitary gland in ewes. Adult ovariectomized ewes (n=8) were fitted with intracerebroventricular (ICV) cannula to facilitate central administration of experimental treatments. Ewes received one of eight treatments [four intravenously (IV) and four ICV]. Peripheral treatments [0 (Veh), 100, …

Farm Focus - Spring 2010, Brian K. Whitlock, Matt Welborn, Maria Prado, Amy Plummer

Faculty Publications and Other Works -- Large Animal Clinical Sciences

No abstract provided.

Balance Training Reduces Falls Risk In Older Individuals With Type 2 Diabetes, Steven Morrison, Sheri R. Colberg, Mita Mariano, Henri K. Parson, Arthur I. Vinik

Rehabilitation Sciences Faculty Publications

OBJECTIVE - This study assessed the effects of balance/strength training on falls risk and posture in older individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS - Sixteen individuals with type 2 diabetes and 21 age-matched control subjects (aged 50-75 years) participated. Postural stability and falls risk was assessed before and after a 6-week exercise program.

RESULTS - Diabetic individuals had significantly higher falls risk score compared with control subjects. The diabetic group also exhibited evidence of mild-to-moderate neuropathy, slower reaction times, and increased postural sway. Following exercise, the diabetic group showed significant improvements in leg strength, faster reaction times, …

The Effect Of Male-Male Competition And Its Underlying Regulatory Mechanisms On The Electric Signal Of The Gymnotiform Fish Brachyhypopomus Gauderio, Vielka Lineth Salazar

FIU Electronic Theses and Dissertations

Sexually-selected communication signals can be used by competing males to settle contests without incurring the costs of fighting. The ability to dynamically regulate the signal in a context-dependent manner can further minimize the costs of male aggressive interactions. Such is the case in the gymnotiform fish Brachyhypopomus gauderio, which, by coupling its electric organ discharge (EOD) waveform to endocrine systems with circadian, seasonal, and behavioral drivers, can regulate its signal to derive the greatest reproductive benefit. My dissertation research examined the functional role of the EOD plasticity observed in male B. gauderio and the physiological mechanisms that regulate the enhanced …

Farm Focus - Fall 2009, Brian K. Whitlock, Matt Welborn, Maria Prado, Amy Plummer

Faculty Publications and Other Works -- Large Animal Clinical Sciences

No abstract provided.

Farm Focus - Spring 2009, Brian K. Whitlock, Matt Welborn, Maria Prado, Amy Plummer

Faculty Publications and Other Works -- Large Animal Clinical Sciences

No abstract provided.

Mice Deficient In The Serine/Threonine Protein Kinase Vrk1 Are Infertile Due To A Progressive Loss Of Spermatogonia, Matthew S. Wiebe, R. Jeremy Nichols, Tyler P. Molitor, Jill K. Lindgren, Paula Traktman

Nebraska Center for Virology: Faculty Publications

The VRK1 protein kinase has been implicated as a proproliferative factor. Genetic analyses of mutant alleles of the Drosophila and Caenorhabditis elegans VRK1 homologs have revealed phenotypes ranging from embryonic lethality to mitotic and meiotic defects with resultant sterility. Herein, we describe the first genetic analysis of murine VRK1. Two lines of mice containing distinct gene-trap integrations into the Vrk1 locus were established. Insertion into intron 12 (GT12) spared VRK1 function, enabling the examination of VRK1 expression in situ. Insertion into intron 3 (GT3) disrupted VRK1 function, but incomplete splicing to the gene trap rendered this allele hypomorphic (~15% of …

The Effects Of Lactation And Negative Energy Balance On Kisspeptin-Stimulated Luteinizing Hormone And Growth Hormone In Dairy Cows, Brian K. Whitlock, Joseph A. Daniel, Robyn R. Wilborn, Herris S. Maxwell, Barbara P. Steele, James L. Sartin

Animal Science Publications and Other Works

Kisspeptin, a neuroendocrine regulator of gonadotropin releasing hormone, is hypothesized to integrate nutrition and hormones critical to metabolism and the regulation of reproduction. Since the negative energy balance of early lactation is associated with reduced fertility via suppression of gonadotropin secretion and enhanced growth hormone (GH) responsiveness, this experiment was designed to determine the effects of stage of lactation and negative energy balance on kisspeptin-10 (Kp-10) stimulated luteinizing hormone (LH) and GH concentrations. Five nonlactating [5.1 ± 0.8 (SEM) years; 577 ± 19 kg body weight (BW)] and five lactating [4.1 ± 0.6 years; 608 ± 11 kg BW] multiparous …

A Carboxyl-Terminal Sequence In The Lutropin Β Subunit Contributes To The Sorting Of Lutropin To The Regulated Pathway, Albina Jablonka-Shariff, Christopher A. Pearl, Anna Comstock, Irving Boime

Peer Reviewed Articles

Although synthesized in the same pituitary gonadotropes, the secretion profiles of lutropin (LH) and follitropin (FSH) differ. LH is secreted through a regulated pathway and associated with a bolus release at mid-estrous cycle. In contrast, the majority of FSH is secreted constitutively with an incremental increase until ovulation. Both share an identicalα subunit, and thus theβ subunit contains determinants for sorting into the regulated pathway. Previously, we demonstrated that a hydrophobic carboxyl-terminal heptapeptide of the LHβ subunit (Leu-Ser-Gly-Leu-Leu-Phe-Leu), not found in the FSHβ subunit, influences the intracellular behavior of the LH dimer. To test the hypothesis that the peptide contributes …

Central Dysregulation Of The Hypothalamic-Pituitary-Adrenal Axis In Neuron-Specific Proopiomelanocortin-Deficient Mice, James L. Smart, Virgine Tolle, Veronica Otero-Corchon, Malcolm J. Low

Faculty Publications - Department of Biological & Molecular Science

No abstract provided.

Physiological Effects On Demography: A Long‐Term Experimental Study Of Testosterone’S Effects On Fitness, W. Reed, M. Clark, P. Parker, S. Raouf, N. Arguedas, D. Monk, E. Snajdr, V. Nolan, E. Ketterson

Biology Department Faculty Works

Understanding physiological and behavioral mechanisms underlying the diversity of observed life‐history strategies is challenging because of difficulties in obtaining long‐term measures of fitness and in relating fitness to these mechanisms. We evaluated effects of experimentally elevated testosterone on male fitness in a population of dark‐eyed juncos studied over nine breeding seasons using a demographic modeling approach. Elevated levels of testosterone decreased survival rates but increased success of producing extra‐pair offspring. Higher overall fitness for testosterone‐treated males was unexpected and led us to consider indirect effects of testosterone on offspring and females. Nest success was similar for testosterone‐treated and control males, …

Targeted Expression Of A Dominant-Negative Fibroblast Growth Factor (Fgf) Receptor In Gonadotropin-Releasing Hormone (Gnrh) Neurons Reduces Fgf Responsiveness And The Size Of Gnrh Neuronal Population, Pei-San Tsai, Suzanne M. Moenter, Hector R. Postigo, Mohammed El Majdoubi, Toni R. Pak, John C. Gill, Sreenivasan Paruthiyil, Sabine Werner, Richard I. Weiner

Collected Faculty and Staff Scholarship

Increasing evidence suggests that fibroblast growth factors (FGFs) are neurotrophic in GnRH neurons. However, the extent to which FGFs are involved in establishing a functional GnRH system in the whole organism has not been investigated. In this study, transgenic mice with the expression of a dominant-negative FGF receptor mutant (FGFRm) targeted to GnRH neurons were generated to examine the consequence of disrupted FGF signaling on the formation of the GnRH system. To first test the effectiveness of this strategy, GT1 cells, a GnRH neuronal cell line, were stably transfected with FGFRm. The transfected cells showed attenuated neurite outgrowth, diminished FGF-2 …

Preservation Of Eumelanin Hair Pigmentation In Proopiomelanocortin-Deficient Mice On A Nonagouti (A/A) Genetic Background, Andrzej Slominski, Przemyslaw M. Plonka, Alexander Pisarchik, James L. Smart, Virgine Tolle, Jacobo Wortsman, Malcolm J. Low

Faculty Publications - Department of Biological & Molecular Science

No abstract provided.

The Anorexigenic Fatty Acid Synthase Inhibitor, C75, Is A Nonspecific Neuronal Activator, Kanji A. Takahashi, James L. Smart, Hongyan Liu, Roger D. Cone

Faculty Publications - Department of Biological & Molecular Science

C75, a recently derived compound that potently suppresses feeding and induces weight loss, has been proposed to act mainly by inhibiting fatty acid synthase (FAS) in central neurons that control feeding. For example, normal, fasting- associated, hypothalamic increases in neuropeptide Y (NPY)/Agouti-related protein (AGRP) expression and decreases in proopiomelanocortin (POMC)/cocaine and amphetamine regulated transcript (CART) expression were reported to be blocked by C75. Using loose-patch extracellular recording in acute slices, we tested the effect of C75 on anorexigenic POMC neurons and orexigenic NPY neurons of the hypothalamic arcuate nucleus, which were identified by promoter-driven GFP expression, as well as on …

Hypothalamic Proopiomelanocortin Neurons Are Glucose Responsive And Express Katp Channels, Nurhadi Ibrahim, Martha A. Bosch, James L. Smart, Jian Qiu, Marcelo Rubinstein, Oline K. Rønnekleiv, Malcolm J. Low, Martin J. Kelly

Faculty Publications - Department of Biological & Molecular Science

Hypothalamic proopiomelanocortin (POMC) neurons are critical for controlling homeostatic functions in the mammal. We used a transgenic mouse model in which the POMC neurons were labeled with enhanced green fluorescent protein to perform visualized, whole-cell patch recordings from prepubertal female hypothalamic slices. The mouse POMC-enhanced green fluorescent protein neurons expressed the same endogenous conductances (a transient outward K current and a hyperpolarization-activated, cation current) that have been described for guinea pig POMC neurons. In addition, the selective -opioid receptor agonist DAMGO induced an outward current (maximum of 12.8 1.2 pA), which reversed at K equilibrium potential (EK), in the majority …

Short Communication: Relationship Between Body Growth And Mammary Development In Dairy Heifers, L F. Silva, M J. Vandehaar, Brian K. Whitlock, R P. Radcliff, H A. Tucker

Faculty Publications and Other Works -- Large Animal Clinical Sciences

Our objective was to determine if prepubertal rate of body weight (BW) gain, independent of diet, was related to mammary development of dairy heifers. Data from two studies recently conducted at Michigan State University were used to identify factors, within a dietary treatment group, that would account for variation in first lactation milk production or amount of mammary parenchymal DNA at the time of puberty. Factors analyzed for variation in milk production during first lactation were: postpartum BW, prepubertal BW gain, gestational BW gain, postpartum BW gain, body condition score (BCS) at breeding, and BCS at calving. Factors analyzed for …

Effect Of Dietary Protein On Prepubertal Mammary Development In Rapidly Growing Dairy Heifers, Brian K. Whitlock, M J. Vandehaar, L F. Silva, H A. Tucker

Faculty Publications and Other Works -- Large Animal Clinical Sciences

The objective was to determine whether increased dietary protein would enhance mammary development in prepubertal heifers fed for rapid body growth (1.2 kg/d). Fifty-four Holstein heifers (weighing approximately 134 kg) were assigned to one of three treatments. Heifers were fed a total mixed ration with metabolizable energy at 2.85 Mcal/kg and metabolizable protein at low, standard, or high concentrations (37, 41, or 44 g/Mcal of metabolizable energy, respectively) from 3.5 mo of age until slaughter at approximately 46 d after puberty. Heifers fed low, standard, and high protein gained 1130, 1170, and 1180 g/d, respectively. Dietary protein did not affect …

Il-1Α And Tnf-Α Down-Regulate Crh Receptor-2 Mrna Expression In The Mouse Heart, Sarah C. Coste, Kurt A. Heldwein, Susan L. Stevens, Eric Tobar-Dupres, Mary P. Stenzel-Poore

Faculty Publications

Two receptors (CRH receptor type 1 and CRH receptor type 2) have been identified for the stress-induced neuropeptide, CRH and related peptides, urocortin, and urocortin II. We previously found marked down-regulation of cardiac CRH receptor type 2 expression following administration of bacterial endotoxin, lipopolysaccharide, a model of systemic immune activation, and inflammation. We postulated that inflammatory cytokines may regulate CRH receptor type 2. We show that systemic IL-1α administration significantly down-regulates CRH receptor type 2 mRNA in mouse heart. In addition, TNFα treatment also reduces CRH receptor type 2 mRNA expression, although the effect was not as marked as with …

Spontaneous And Induced Genetic Mutations Of The Pomc System, James L. Smart, Malcolm J. Low

Faculty Publications - Department of Biological & Molecular Science

No abstract provided.