Expression of a heroin contextually conditioned immune effect in male rats requires CaMKII alpha-expressing neurons in dorsal, but not ventral, subiculum and hippocampal CA1
BRAIN BEHAVIOR AND IMMUNITY
Authors: Lebonville, Christina L.; Paniccia, Jacqueline E.; Parekh, Shveta V.; Wangler, Lynde M.; Jones, Meghan E.; Fuchs, Rita A.; Lysle, Donald T.
Abstract
The physiological and motivational effects of heroin and other abused drugs become associated with environmental (contextual) stimuli during repeated drug use. As a result, these contextual stimuli gain the ability to elicit drug-like conditioned effects. For example, after context-heroin pairings, exposure to the heroin-paired context alone produces similar effects on peripheral immune function as heroin itself. Conditioned immune effects can significantly exacerbate the adverse health consequences of heroin use. Our laboratory has shown that exposure to a heroin-paired context suppresses lipopolysaccharide (LPS)-induced splenic nitric oxide (NO) production in male rats, and this effect is mediated in part by the dorsal hippocampus (dHpc). However, specific dHpc output regions, whose efferents might mediate conditioned immune effects, have not been identified, nor has the contribution of ventral hippocampus (vHpc) been investigated. Here, we evaluated the role of CaMKII alpha-expressing neurons in the dHpc and vHpc main output regions by expressing Gi-coupled designer receptors exclusively activated by designer drugs (DREADDs) under a CaMKII alpha promoter in the dorsal subiculum and CA1 (dSub, dCA1) or ventral subiculum and CA1 (vSub, vCA1). After context-heroin conditioning, clozapine-N-oxide (CNO, DREADD agonist) or vehicle was administered systemically prior to heroin-paired context (or home-cage control) exposure and LPS immune challenge. Chemogenetic inhibition of CaMKII alpha-expressing neurons in dHpc, but not vHpc, output regions attenuated the expression of conditioned splenic NO suppression. These results establish that the main dHpc output regions, the dSub and dCA1, are critical for this context-heroin conditioned immune effect.
Antinociceptive activity of Schinus terebinthifolia leaf lectin (SteLL) in sarcoma 180-bearing mice
JOURNAL OF ETHNOPHARMACOLOGY
Authors: Marques Ramos, Dalila de Brito; de Moura Fontes Araujo, Maria Tais; de Lima Araujo, Tarcisio Cicero; Silva, Yasmym Araujo; Lima Amorim dos Santos, Angela Carolina; Gama e Silva, Mariana; Guedes Paiva, Patricia Maria; Mendes, Rosemairy Luciane; Napoleao, Thiago Henrique
Abstract
Ethnopharmacology relevance: Schinus terebinthifolia Raddi leaves have been used in folk medicine due to several properties, including antitumor and analgesic effects. The variable efficacy and adverse effects of analgesic drugs have motivated the search for novel antinociceptive agents. It has been reported that the S. terebinthifolia leaf lectin (SteLL) has antitumor activity against sarcoma 180 in mice. Aim of the study: This work aimed to evaluate whether SteLL would reduce cancer pain using an orthotopic tumor model. Materials and methods: A sarcoma 180 cell suspension was inoculated into the right hind paws of mice, and the treatments (150 mM NaCl, negative control; 10 mg/kg morphine, positive control; or SteLL at 1 and 2 mg/kg) were administered intraperitoneally 24 h after cell inoculation up to 14 days. Spontaneous nociception, mechanical hyperalgesia, and hot-plate tests were performed. Further, the volume and weight of the tumor-bearing paws were measured. Results: SteLL (2 mg/kg) improved limb use during ambulation. The lectin (1 and 2 mg/kg) also inhibited mechanical hyperalgesia and increased the latency time during the hot-plate test. Naloxone was found to reverse this effect, indicating the involvement of opioid receptors. The tumor-bearing paws of mice treated with SteLL exhibited lower volume and weight. Conclusion: SteLL reduced hyperalgesia due to sarcoma 180 in the paws of mice, and this effect can be related to its antitumor action.