targeted-toxins

Kozikowski CT, Wolfe EL, Yanev PG, Burk JA (2014) Interactions between noncholinergic basal forebrain neurons and muscarinic receptors in attentional processing. Neuroscience 2014 Abstracts 263.16. Society for Neuroscience, Washington, DC.

Summary: Numerous studies have provided evidence that basal forebrain corticopetal cholinergic neurons are critical for normal attentional performance. However, the role of noncholinergic basal forebrain neurons in attention has not been well-characterized. Moreover, evidence regarding interactions between cholinergic receptor activity and noncholinergic basal forebrain neurons remains scarce. In the present experiment, rats (n=15) were trained in a two-lever sustained attention task that required to discriminate between brief illumination of a centrally located panel light (500, 100, 25 ms) from trials when the light was not illuminated. After reaching criterion performance, rats received infusions into the basal forebrain of saline (n=7) or the immunotoxin, GAT1-saporin (n=8), to lesion noncholinergic neurons. After re-establishing performance after surgery, all rats received systemic administration of the muscarinic receptor antagonist, scopolamine (0, 0.05, 0.20 mg/kg, ip). When attentional testing resumed after surgical recovery, lesioned animals’ task performance did not significantly differ from sham-lesioned animals. However, following the highest dose of scopolamine, lesioned animals exhibited a larger decline in signal detection accuracy compared to sham-lesioned animals. Additionally, lesioned animals’ omission rate was higher during injection sessions compared to sham-lesioned animals. These results suggest that noncholinergic basal forebrain neurons are not necessary for performance in a well-trained attention task. However, loss of these neurons renders animals’ attentional performance more vulnerable to decreased cholinergic system stimulation. Finally, the lesion-induced increase in omissions may reflect a role for noncholinergic basal forebrain neurons in processes beyond attention.

Related Products: GAT1-SAP (Cat. #IT-32)

Dinh TT, Huston N, Ritter S (2014) Lesions of hindbrain catecholaminergic projections to nucleus accumbens, bed nucleus of the stria terminalis, lateral parabrachial nucleus or locus coeruleus do not impair glucoprivic feeding. Neuroscience 2014 Abstracts 256.05. Society for Neuroscience, Washington, DC.

Summary: We have shown previously that injection of the retrogradely transported immunotoxin, anti-dopamine beta-hydroxylase (DBH) saporin (DSAP), into the paraventricular nucleus of the hypothalamus (PVH) or arcuate nucleus, abolishes feeding in response to central or systemic glucoprivation. Since DSAP injection destroys DBH-expressing neurons with projections to the injection site, these results strongly implicate hindbrain catecholamine neurons as major mediators of glucoprivic feeding. In order to further define the essential circuitry underlying glucoprivic feeding, we injected DSAP into these additional sites: locus coeruleus (LC), accumbens shell (AcbSh), ventrolatersal bed nucleus of the stria terminalis (vlBNST) and lateral parabrachial nucleus (LPBN). These sites are innervated by hindbrain catecholamine neurons and some sites receive collateral innervation from PVH-projecting catecholamine neurons. Appropriate placement and volume for DSAP administration was determined by co-labeling of DBH-ir neurons with retrograde tracer injected into target sites. Lesions were confirmed by postmortem evaluation of DSAP injection site and by hindbrain catecholamine cell and terminal loss. We found that the feeding response to systemic glucoprivation was not significantly or permanently impaired by injection of DSAP into any of these sites. Based on our results to date, we tentatively conclude that direct projections from hindbrain catecholamine neurons to the LC, AcbSh, vlBNST and LPBN are not required for glucoprivic feeding. The hypothalamus appears to be the major recipient of direct innervation from catecholamine neurons required for glucoprivic feeding

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Fu R, Chen X, Zho W, Li J, Ye J-H (2014) Selective ablation of mu opioid receptor expressing gaba neurons in the rostromedial tegmental nucleus promotes ethanol intake. Neuroscience 2014 Abstracts 267.30. Society for Neuroscience, Washington, DC.

Summary: BACKGROUND AND PURPOSE The cellular mechanisms underlying the aversive effect of ethanol that limits its intake are not well understood, although recent evidence has linked aversion with synaptic inhibition of dopamine neurons in the ventral tegmental area. Emerging evidence indicates that the rostromedial tegmental nucleus (RMTg), a newly defined midbrain structure exerts a major GABAergic inhibitory control over midbrain dopamine neurons and encodes aversive stimuli. The RMTg contains mostly GABAergic neurons and with dense μ-opioid receptor (MOR) immunoreactivity. However, the role of RMTg in the regulation of ethanol intake has not been well investigated. EXPERIMENTAL APPROACH We compared voluntary ethanol intake and locomotion in rats with intra-RMTg infusion of dermorphin-saporin or blank saporin. Dermorphin-saporin is a neurotoxin, which could selectively lesion MOR-expressing neurons. We measured ethanol intake in rats given intermittent access to ethanol (20% vol/vol) using a two bottle choice paradigm. We euthanized the rats, dissected their brains and analyzed the glutamic acid decarboxylase67 (GAD67) and MOR protein expression and immunoreactivity immediately following the behavioral test. KEY RESULTS In rats that received intra-RMTg injection of dermorphin-saporin, we observed a robust increase in the intake of and the preference to ethanol, and in the locomotor activity; but a significantly reduced GAD67 and MOR protein expression, as well as a massive loss of neurons with GAD67 and MOR immunoreactivity within the RMTg. We observed no such changes in rats that received injection of blank saporin or saline. Together, These findings indicate that MOR-expressing GABA neurons in the RMTg play a crucial role in the regulation of ethanol consumption, implicating the dysfunction of these neurons likely play a critical role in the pathogenesis of alcoholism, and that these neurons should represent an appropriate target for the development of therapeutic strategies against alcohol use disorders.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Kalinchuk A, Porkka-Heiskanen T, McCarley R, Basheer R (2015) Cholinergic neurons of the basal forebrain mediate biochemical and electrophysiological mechanisms underlying sleep homeostasis. Eur J Neurosci 41:182-195. doi: 10.1111/ejn.12766

Summary: Previous work has indicated that non-rapid eye movement during recovery sleep after sleep deprivation requires cholinergic neurons in the BF. The authors examined how BF cholinergic neurons affect the levels of HSP markers during sleep deprivation. Rats received 230-ng injections of 192-IgG-SAP (Cat. #IT-01) into the horizontal limb of the diagonal band/substantia innominata/ magnocellular preoptic area. The results indicate that cholinergic neurons in the BF are important for regulating the biochemical and EEG mechanisms that contribute to HSP.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Frankel AE, Nymeyer H, Lappi DA, Higgins D, Ahn C, Noe C (2014) Preliminary results from a phase I study of substance P-saporin in terminal cancer patients with intractable pain. Journal of Clinical Oncology 32:191. doi: 10.1200/jco.2014.32.31_suppl.191

Summary: Existing pain therapies are insufficient to control cancer pain in 10-15% of patients. Substance P (SP) and its receptor, neurokinin-1 (NK-1r) have been determined to play a major role in spinal transmission of chronic pain. Animal studies have demonstrated that disruption of the NK-1r pathway alleviates chronic pain caused by a variety of stimuli. The authors are conducting a Phase I clinical trial in humans (NCT02036281) assessing the ability of SP-SAP (Cat. #IT-07) to treat intractable chronic pain due to cancer. Patients have received intrathecal injections of 1, 2, or 4 µg of SP-SAP with no evidence of toxicity or neurological or cardiac abnormalities. Doses will escalate up to 90 µg.

Related Products: SP-SAP (Cat. #IT-07)

Akiyama T, Tominaga M, Takamori K, Carstens M, Carstens E (2014) Role of spinal bombesin-responsive neurons in nonhistaminergic itch. J Neurophysiol 112:2283-2289. doi: 10.1152/jn.00409.2014

Summary: Recent papers have demonstrated that pruritogen-evoked scratching behavior is reduced or eliminated by intrathecal injection of Bombesin-SAP (Cat. #IT-40). In this work the authors build on those data by investigating if spinal neurons that are responsive to pruritogens administered intradermally are also responsive to a spinal infusion of bombesin. Through the use of intradermal chloroquine injections, spinal superfusion of bombesin, and noxious pinch, the overlap of neurons processing itch and nociception was examined. The results demonstrate that chloroquine- and bombesin-sensitive neurons are involved in the transmission of itch, and that these are a separate neuronal population from those involved in nociception.

Related Products: Bombesin-SAP (Cat. #IT-40)

Q: I ordered a control conjugate to use alongside my targeted conjugate, but the two products are at different concentrations. How much control conjugate should I use?

A: Conjugate products are often of differing protein concentrations, meaning dilution of one is usually necessary to ensure comparable amounts of control conjugate and targeted conjugate are used. This adjustment can be done on a molar basis or a protein concentration basis. The data sheet shipped with each Advanced Targeting System conjugate specifies the molecular weight of the product. There are various calculators available on the ATS website.

By using these tools, calculations can be done that will ensure the same number of molecules of both control and targeted conjugate are used in your experiment. Alternatively, if the molecular weights of the two products are similar, calculations can be done to use the same amount of control protein as targeted conjugate protein in your experiment.

Zhao Z, Wan L, Liu X, Huo F, Li H, Barry D, Krieger S, Kim S, Liu Z, Xu J, Rogers B, Li Y, Chen Z (2014) Cross-inhibition of NMBR and GRPR signaling maintains normal histaminergic itch transmission. J Neurosci 34:12402-12414. doi: 10.1523/JNEUROSCI.1709-14.2014

Summary: After itch detection, the itch pathway moves through an array of G-protein coupled receptors and transient receptor potential channels in dorsal root ganglion neurons into dorsal horn neurons which integrate and transduce these signals, sending them to the somatosensory cortex. The purpose of this work is to clarify whether gastrin-releasing peptide (GRP) or B-type natriuretic peptide regulates histaminergic itch. Several strains of knockout mice received 200, 300, or 400 ng intrathecal injections of bombesin-SAP (Cat. #IT-40). Blank-SAP (Cat. #IT-21) was used as a control. The data further define the respective functions of the neuromedin B receptor and GRP receptor in itch, and reveals a working relationship between the different interneuron populations.

Related Products: Bombesin-SAP (Cat. #IT-40), Blank-SAP (Cat. #IT-21)

Zhang G, Liu Z, Zhang B, Geng W, Song N, Zhou W, Cao Y, Li S, Huang Z, Shen L (2014) Orexin A activates hypoglossal motoneurons and enhances genioglossus muscle activity in rats. Br J Pharmacol 171:4233-4246. doi: 10.1111/bph.12784

Summary: Orexin neurons are restricted to the lateral hypothalamus (LH) and are involved in functions such as feeding behavior, energy homeostasis, sleep/wake cycles, and many others. Here the authors investigate orexin control of the genioglossus – the largest upper airway dilator muscle. Rats received bilateral 172 ng injections of orexin-SAP into the LH. Lesioned animals displayed a significant decrease in genioglossus muscle electromyograms, indicating that orexin neurons are vital to the control of this muscle.

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

Shah M, Vella A (2014) Effects of GLP-1 on appetite and weight. Rev Endocr Metab Disord 15(3):181-187. doi: 10.1007/s11154-014-9289-5 PMID: 24811133

Objective: To determine if the synergistic actions of GLP-1 in the gut and brain, acting on both central and peripheral receptors are responsible for the effects of the hormone on satiety.

Summary: The effect of GLP-1 on satiety is primarily derived from its action on anorexigenic hormones so that when NPY/ AgRP neurons are specifically eliminated by NPY-SAP, the effect of GLP-1 on decreasing satiation persists.

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

See Also:

• Bugarith K et al. Basomedial hypothalamic injections of neuropeptide Y conjugated to saporin selectively disrupt hypothalamic controls of food intake. Endocrinology 146(3):1179-1191, 2005.