control-conjugates

Wiater MF, Oostrom M, Barfield R, Dinh TT, Li A-J, Ritter S (2010) Leptin-saporin lesions of the arcuate nucleus induce an arrhythmic circadian feeding pattern. Neuroscience 2010 Abstracts 733.6. Society for Neuroscience, San Diego, CA.

Summary: The endogenous circadian rhythm of feeding is incompletely understood. The leptin sensitive network within the arcuate nucleus (Arc) of the hypothalamus is important for the control of feeding. Genetic deletion of leptin or leptin receptors results in profound obesity, hyperphagia, and the loss of day/night differences in food intake. Because the Arc is critically involved in control of food intake and contains leptin receptors, we hypothesized that the Arc plays an important role in maintenance of feeding rhythms. To examine this hypothesis, we injected a newly developed targeted toxin, leptin conjugated to saporin (LSAP), into the Arc to lesion leptin receptor-expressing neurons in the vicinity of the injection. Controls were injected saporin conjugated to a peptide with no known action or receptor (blank-saporin, BSAP). We expected the Arc LSAP would disrupt the circadian rhythm of food intake, as seen in rats with genetic deletion of leptin or its receptor. Eating rhythms were monitored continuously (each minute) over a 60-day period using BioDAQ (Research Diets) automated meal monitoring equipment. Data were analyzed for circadian rhythm using ClockLab (ActiMetrics) software. Eatograms (food intake in actogram format), showing eating times and durations comparable to actograms used for wheel-running activity, and Chi-square periodograms were generated. Feeding was monitored in light:dark, dark:dark, or light:light conditions. The LSAP injection caused profound hyperphagia, weight gain and disrupted circadian feeding patterns. Although LSAP rats remained sensitive to light and dark under certain circumstances and were capable of an apparent rhythm during light:dark conditions, feeding was arrhythmic by all measures when photic cues were removed (i.e., in dark:dark and light:light conditions). At the end of experimentation, lesions were analyzed using immunohistochemistry to detect agouti gene related protein (AGRP) and α-melanocortin stimulating hormone (α-MSH) neurons, both known to express leptin receptors. Cell bodies positive for these peptides were greatly diminished in the Arc. Results indicate that the Arc contributes importantly to the expression of circadian rhythms of food intake.

Related Products: Leptin-SAP (Cat. #IT-47), Blank-SAP (Cat. #IT-21)

Wiater MF, Mukherjee S, Dinh TT, Rooney E, Li A-J, Simasko SM, Ritter S (2010) The arcuate nucleus of the hypothalamus controls the circadian distribution of sleep and feeding. Neuroscience 2010 Abstracts 648.16/H17. Society for Neuroscience, San Diego, CA.

Summary: Integration of daily sleep and feeding rhythms is incompletely understood. We examined the role of the hypothalamic arcuate nucleus (Arc) in these processes using Arc microinjections of the targeted toxin, NPY-saporin (NPY-SAP), or control blank-saporin (B-SAP). NPY-sap targets and destroys NPY receptor-expressing neurons. We monitored 24 hr feeding over a 30-day period beginning 2 wks after the Arc injections, and used EEG recordings to assign vigilance states. Vigilance was divided into rapid-eye movement sleep (REMS), non-REMS (NREMS) and wake. NPY-SAP lesioned rats were hyperphagic , consuming up to 225% of pre-injection baseline. They rapidly became obese. While in the sleep-monitoring chambers, their body weight change per week ranged from 56 ± 9 g to 40.5 ± 4.5g, compared to 6 ± 0.4 g/wk for B-SAP rats. Their circadian pattern of food intake was severely disrupted, such that intake in light and dark periods were approximately equal (43% of their total intake was consumed in the light period vs. 25% in B-SAP controls). Sleep patterns were also significantly disrupted in the NPY-SAP animals. The occurrence of rapid eye movement sleep (REMS) was inverted in phase, occurring mainly at night, rather than during the day. NonREMS was distributed equally across day and night, instead of occurring predominantly during the day. However, 24-hr total REMS and NREMS time was normal. B-SAP controls had normal sleep patterns, with NREMS and REMS occurring predominantly in the light phase. To determine if the change in sleep pattern was due to the change in feeding patterns, we restricted access to food to the dark period for 4 days. NPY-SAP treated animals doubled their food intake in the dark period. However, sleep patterns were not changed compared to the ad libitum feeding period in either NPY-SAP or B-SAP rats. After 7 days of ad libitum feeding, we restricted food access to the light period for 4 days. Again, NPY-SAP animals doubled their intake during the feeding period, this time during the light phase, and sleep patterns were not changed in either group by the restricted feeding. By 100 days post-lesion, the NPY-sap animals were still obese, but the patterning and amount of their food intake were becoming similar to controls. However, when evaluated again, sleep patterns were still altered to the same degree as observed early post-lesion. These results confirm the importance of NPY-receptive Arc neurons in controlling food intake. They also reveal an unexpected role for the Arc in the timing of both NREMS and REMS that appears to be independent of the patterning of food intake.

Related Products: NPY-SAP (Cat. #IT-28), Blank-SAP (Cat. #IT-21)

Burke PG, Neale J, Korim WS, Mcmullan S, Pilowsky PM, Goodchild AK (2010) Patterning of somatosympathetic reflexes: Identification of distinct bulbospinal sympathoexcitatory RVLM projections by conduction velocity and catecholamine phenotype. Neuroscience 2010 Abstracts 694.11/HHH34. Society for Neuroscience, San Diego, CA.

Summary: The aim of this study was to examine the somatosympathetic reflex (SSR) response of different sympathetic nerves to identify distinct projections of presympathetic vasomotor RVLM neurons by axonal conduction and catecholamine phenotype. All experiments were conducted in urethane-anaesthetised (1.3 g/kg ip), paralysed, vagotomised and artificially ventilated Sprague Dawley rats (n = 44). First, we determined the simultaneous activity of dorsal root potentials and the splanchnic SSR to single shock sciatic nerve (SN) stimulation (single 0.2 ms pulse, 50 sweeps at 0.5-1 Hz, 1-80 V, n=4). Second, we simultaneously recorded the sympathoexcitatory response of multiple, sympathetic nerves (cervical, renal, splanchnic and lumbar) to low (A-fibre afferent; 4-10 V) and high (A- and C-fibre afferents; +40 V) SN stimulation (n=19). Third, we examined the cervical or splanchnic SSR to low intensity SN stimulation in rats following RVLM microinjection of somatostatin (SST) or muscimol (n=8). Fourth, we examined the splanchnic SSR in rats pretreated with intraspinal anti-dopamine-beta-hydroxylase-saporin (anti-DβH-SAP; 24 ng/side, n=8), a neurotoxin that depleted ~70% of catecholamine (C1) neurons in the RVLM compared to IgG-saporin control (n=5). Low intensity SN stimulation evoked biphasic responses in the renal, splanchnic and lumbar nerves but a single peak in the cervical nerve. High intensity SN stimulation evoked triphasic responses in the renal, splanchnic and lumbar nerves and a biphasic cervical response. RVLM injections of SST abolished the early peak of the cervical and splanchnic SSR. Intraspinal pretreatment with anti-DβH-SAP eliminated the late peak of the splanchnic SSR and attenuated the first peak. It is concluded that the mono- or bi-phasic SSR responses are generated by A-fibre afferent inputs driving two classes of bulbospinal sympathoexcitatory RVLM neurons with myelinated or unmyelinated axonal conduction. Secondly, unmyelinated RVLM presympathetic neurons, presumed to be all C1, innervate splanchnic, renal and lumbar SPN, whereas myelinated C1 and non-C1 neurons innervate all sympathetic outflow examined. These findings extend prior evidence that the RVLM expresses several types of phenotypically distinct descending sympathoexcitatory pathways.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

Lyons AM, Thiele TE (2010) Neuropeptide Y conjugated to saporin alters anxiety-like behavior when injected into the central nucleus of the amygdala or basomedial hypothalamus in BALB/cJ mice. Peptides 31(12):2193-2199. doi: 10.1016/j.peptides.2010.09.009

Summary: Neuropeptide Y (NPY) in the hypothalamus is known to modulate feeding behavior. In this work the authors used bilateral 48 ng injections of NPY-SAP (Cat. #IT-28) into the central amygdala or basomedial hypothalamus (BMH) of rats to investigate the role of NPY in anxiety. Blank-SAP (Cat. #IT-21) was used as a control. Injections into the amygdala increased anxiety-like behavior, while injections into the BMH reduced anxiety-like behavior. BMH injections also initiated an increase of NPY-1 receptor expression in the basolateral nuclei of the amygdala.

Related Products: NPY-SAP (Cat. #IT-28), Blank-SAP (Cat. #IT-21)

Di Sebastiano AR, Wilson-Perez HE, Lehman MN, Coolen LM (2011) Lesions of orexin neurons block conditioned place preference for sexual behavior in male rats. Horm Behav 59(1):1-8. doi: 10.1016/j.yhbeh.2010.09.006

Summary: The neuropeptide orexin is important in the feedback mechanisms of food intake and drugs of abuse. This work investigates the role of orexin in sexual reward in male rats. Two 200 ng bilateral hypothalamic injections of orexin-SAP (Cat. #IT-20) were made into each hemisphere. Blank-SAP (Cat. #IT-21) was used as a control. Although it was shown orexin neurons are activated by sexual reward cures, the data suggest that orexin is not essential for sexual performance and motivation.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)

Baskin DG, Kim F, Gelling RW, Russell BJ, Schwartz MW, Morton GJ, Simhan HN, Moralejo DH, Blevins JE (2010) A new oxytocin-saporin cytotoxin for lesioning oxytocin-receptive neurons in the rat hindbrain. Endocrinology 151(9):4207-4213. doi: 10.1210/en.2010-0295

Summary: There is evidence to suggest that release of oxytocin in the nucleus tractus solitarius (NTS) of the hindbrain can inhibit food intake by augmenting the cholecystokinin satiety response. In order to add support to this hypothesis the authors used oxytocin-SAP (Cat. #IT-46) to eliminate oxytocin receptive cells in the NTS. Blank-SAP (Cat. #IT-21) was used as a control. 0.5 µl-injections of oxytocin-SAP into the NTS caused reduced satiation effect of CCK-8 and blocked the stimulation of food intake by an oxytocin receptor antagonist.

Related Products: Oxytocin-SAP (Cat. #IT-46), Blank-SAP (Cat. #IT-21)

Northrop LE, Polston EK, Erskine MS (2010) Noradrenergic nuclei that receive sensory input during mating and project to the ventromedial hypothalamus play a role in mating-induced pseudopregnancy in the female rat. J Neuroendocrinol 22(10):1061-1071. doi: 10.1111/j.1365-2826.2010.02049.x

Summary: Maintenance of pregnancy or pseudopregnancy in rats is maintained by bicircadian prolactin surges induced by vaginal-cervical stimulation. In order to test the hypothesis that medullary noradrenergic cell groups are involved in this process the authors infused rats with either 2 ng or 60 ng anti-DBH-SAP (Cat. #IT-03) into the ventrolateral division of the ventromedial hypothalamus (VMHv1) and the posterodorsal medial amygdala. Mouse IgG-Sap (Cat. #IT-18) was used as a control. The data confirm that noradrenergic neurons are involved in the maintenance of pregnancy or pseudopregnancy.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

de Carvalho D, Bicego KC, de Castro OW, da Silva GS, Garcia-Cairasco N, Gargaglioni LH (2010) Role of neurokinin-1 expressing neurons in the locus coeruleus on ventilatory and cardiovascular responses to hypercapnia. Respir Physiol Neurobiol 172(1-2):24-31. doi: 10.1016/j.resp.2010.04.016

Summary: NK-1 receptors (NK1R) play an important role in cardiorespiratory responses to hypercapnia. In order to paint a clearer picture of the systems involved the authors injected 0.4 µl of 2 µM SP-SAP (Cat. #IT-07) into the locus coeruleus (LC) of rats. Mouse IgG-SAP (Cat. #IT-18) was used as a control. The data suggest that several subpopulations of neurons express NK1R in the LC, and that these subpopulations play different roles in the modulation of cardiorespiratory reponses to hypercapnia.

Related Products: SP-SAP (Cat. #IT-07), Mouse IgG-SAP (Cat. #IT-18)

Potes CS, Turek VF, Cole RL, Vu C, Roland BL, Roth JD, Riediger T, Lutz TA (2010) Noradrenergic neurons of the area postrema mediate amylin’s hypophagic action. Am J Physiol Regul Integr Comp Physiol 299(2):R623-631. doi: 10.1152/ajpregu.00791.2009

Summary: Amylin decreases food intake in rats and is a satiation signal affecting the area postrema (AP). This work investigated the role of noradrenergic neurons in amylin activity. Rats received a total of 50 ng of anti-DBH-SAP (Cat. #IT-03) into the AP and 25 ng into the lateral parabrachial nucleus. Mouse IgG-SAP (Cat. #IT-18) was used as a control. Rats showing a >50% lesion of noradrenergic neurons were unresponsive to low doses of amylin, suggesting that noradrenergic neurons are part of the amylin pathway.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

Di Sebastiano AR, Yong-Yow S, Wagner L, Lehman MN, Coolen LM (2010) Orexin mediates initiation of sexual behavior in sexually naive male rats, but is not critical for sexual performance. Horm Behav 58(3):397-404. doi: 10.1016/j.yhbeh.2010.06.004

Summary: In this work the role of endogenous orexin-A and B in male sexual behavior was investigated. Rats received a total of 400 ng of orexin-SAP (Cat. #IT-20) into the hypothalamus in each hemisphere. Blank-SAP (Cat. #IT-21) was used as a control. The lesions facilitated initiation of sexual behavior in naïve males, and reduced anxiety-like behaviors. The data suggest that orexin may play a role in arousal and anxiety related to sexual behavior in naïve animals, but is not critical for performance or motivation.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)