RESUMEN
Kisspeptin and γ-amino butyric acid (GABA), synthesized in the central nervous system, are critical for reproduction. Both are also expressed in peripheral organs/tissues critical to metabolic control (liver/pancreas/adipose). Many kisspeptin neurons coexpress GABAB receptors (GABABR) and GABA controls kisspeptin expression and secretion. We developed a unique mouse lacking GABABR exclusively from kisspeptin cells/neurons (Kiss1-GABAB1KO) to evaluate the impact on metabolism/reproduction. We confirmed selective deletion of GABABR from Kiss1 cells in the anteroventral periventricular nucleus/periventricular nucleus continuum (AVPV/PeN; immunofluorescence and PCR) and arcuate nucleus (ARC), medial amygdala (MeA), pituitary, liver, and testes (PCR). Young Kiss1-GABAB1KO males were fertile, with normal LH and testosterone. Kiss1 expression was similar between genotypes in AVPV/PeN, ARC, MeA, bed nucleus of the stria terminalis (BNST), and peripheral organs (testis, liver, pituitary). Kiss1-GABAB1KO males presented higher fasted glycemia and insulin levels, an impaired response to a glucose overload, reduced insulin sensitivity, and marked insulin resistance. Interestingly, when Kiss1-GABAB1KO males got older (9 mo old) their body weight (BW) increased, in part due to an increase in white adipose tissue (WAT). Old Kiss1-GABAB1KO males showed higher fasted insulin, increased pancreatic insulin content, insulin resistance, and significantly decreased pancreatic kisspeptin levels. In sum, lack of GABABR specifically in Kiss1 cells severely impacts glucose homeostasis in male mice, reinforcing kisspeptin involvement in metabolic regulation. These alterations in glucose homeostasis worsened with aging. We highlight the impact of GABA through GABABR in the regulation of the pancreas kisspeptin system in contrast to liver kisspeptin that was not affected.NEW & NOTEWORTHY We developed a unique mouse lacking GABAB receptors specifically in Kiss1 cells to evaluate the impact on reproduction and metabolism. Knockout males showed a severe impact on glucose homeostasis, which worsened with aging. These results reinforce the proposed kisspeptin involvement in metabolic regulation and highlight the impact of GABA through GABABR in the regulation of the peripheral pancreas kisspeptin system.
Asunto(s)
Resistencia a la Insulina , Insulinas , Ratones , Animales , Masculino , Kisspeptinas/genética , Kisspeptinas/metabolismo , Resistencia a la Insulina/genética , Estradiol/metabolismo , Ratones Noqueados , Reproducción/genética , Homeostasis , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Female mice lacking GABAB receptors, GABAB1KO, show disrupted oestrous cycles, reduced pregnancies and increased hypothalamic Gnrh1 mRNA expression, whereas anteroventral periventricular/periventricular preoptic nucleus (AVPV/PeN) Kiss1 mRNA was not affected. In the present study, we characterise the important components of the gonadotrophic preovulatory surge, aiming to unravel the origin of this reproductive impairment. In GABAB1KO and wild-type (WT) females, we determined: (i) hypothalamic oestrogen receptor (ER)α and ß and aromatase mRNA and protein expression; (ii) ovulation index and oestrus serum follicle-stimulating hormone (FSH) and pituitary Gnrh1r expression; (iii) in ovariectomised-oestradiol valerate-treated mice, we evaluated ex vivo hypothalamic gonadotrophin-releasing hormone (GnRH) pulsatility in the presence/absence of kisspeptin (Kiss-10, constant or pulsatile) and oestradiol (constant); and (iv) in ovariectomised-oestradiol silastic capsule-treated mice (proestrous-like environment), we evaluated morning and evening kisspeptin neurone activation (c-Fos+) and serum luteinising homrone (LH). In the medial basal hypothalamus of oestrus GABAB1KOs, aromatase and ERα mRNA and protein were increased, whereas ERß was decreased. In GABAB1KOs, the ovulation index was decreased together with decreased first oestrus serum FSH and increased pituitary Gnrh1r mRNA. Under constant Kiss-10 stimulation, hypothalamic GnRH pulse frequency did not vary, although GnRH mass/pulse was increased in GABAB1KOs. In WTs, pulsatile Kiss-10 together with constant oestradiol significantly increased GnRH pulsatility, whereas, in GABAB1KOs, oestradiol alone increased GnRH pulsatility and this was reversed by pulsatile Kiss-10 addition. In GABAB1KOs AVPV/PeN kisspeptin neurones were similarly activated (c-Fos+) in the morning and evening, whereas WTs showed the expected, marked evening stimulation. LH correlated with activated kisspeptin cells in WT mice, whereas GABAB1KO mice showed high, similar LH levels both in the morning and evening. Taken together, all of these alterations point to impairment in the trigger of the preovulatory GnRH surge that entails the reproductive alterations described.
Asunto(s)
Ciclo Estral/sangre , Ciclo Estral/genética , Hormona Luteinizante/sangre , Inhibición de la Ovulación , Receptores de GABA-B/genética , Animales , Estradiol/sangre , Femenino , Hormona Folículo Estimulante/sangre , Hormona Liberadora de Gonadotropina/sangre , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Ovulación/sangre , Ovulación/genética , Inhibición de la Ovulación/sangre , Inhibición de la Ovulación/genética , Regulación hacia Arriba/genéticaRESUMEN
BACKGROUND: Anti-inflammatory and immunologic properties of cannabinoids have been reported in several tissues. Expression of cannabinoid receptor Type 2 was reported in osteoblasts and osteoclasts, suggesting a key role in bone metabolism. The aim of this study is to assess the effect of treatment with cannabinoid-2 receptor agonist HU-308 in the oral health of rats subjected to lipopolysaccharide (LPS)-induced periodontitis. METHODS: Twenty-four rats were distributed in four groups (six rats per group): 1) control rats; 2) sham rats; 3) rats submitted to experimental periodontitis (LPS); and 4) rats submitted to experimental periodontitis and treated with HU-308 (LPS+HU). In groups LPS and LPS+HU, periodontitis was induced by LPS (1 mg/mL) injected into the gingival tissue (GT) of maxillary and mandibular first molars and into the interdental space between the first and second molars, 3 days per week for 6 weeks. In group LPS+HU, HU-308 (500 ng/mL) was applied topically to the GT daily. RESULTS: Alveolar bone loss resulting from LPS-induced periodontitis was significantly attenuated with HU-308 treatment (LPS+HU), measured by macroscopic and histologic examination. Treatment also reduced gingival production of inflammatory mediators augmented in LPS-injected rats, such as: 1) inducible nitric oxide (iNOS) activity (LPS: 90.18 ± 36.51 pmol/minute/mg protein versus LPS+HU: 16.37 ± 4.73 pmol/minute/mg protein; P <0.05); 2) tumor necrosis factor alpha (LPS: 185.70 ± 25.63 pg/mg protein versus LPS+HU: 95.89 ± 17.47 pg/mg protein; P <0.05); and 3) prostaglandin E2 (PGE2) (LPS: 159.20 ± 38.70 pg/mg wet weight versus LPS+HU: 71.25 ± 17.75 pg/mg wet weight; P <0.05). Additionally, HU-308 treatment prevented the inhibitory effect of LPS-induced periodontitis on the salivary secretory response to pilocarpine. Moreover, iNOS activity and PGE2 content, which were increased by LPS-induced periodontitis in the submandibular gland, returned to control values after HU-308 treatment. CONCLUSION: This study demonstrates anti-inflammatory, osteoprotective, and prohomeostatic effects of HU-308 in oral tissues of rats with LPS-induced periodontitis.
Asunto(s)
Cannabinoides/farmacología , Periodontitis/dietoterapia , Pérdida de Hueso Alveolar , Animales , Lipopolisacáridos , Ratas , Receptores de CannabinoidesRESUMEN
The aim of the present study was to perform a biochemical, histological, and histomorphometrical evaluation of the mechanisms involved in tissue repair in rats subjected to submandibulectomy-induced hyposialia, 24, 48, and 72 hours of post-tooth extraction. We studied the correlation between the lack of submandibular saliva and the modulation of inflammatory mediators involved in tissue repair, such as prostaglandin E2 , nitric oxide (NO), and tumor necrosis factor alpha (TNF-α). Rats with hyposialia showed a delay in socket healing, slow replacement of the clot with granulation tissue, and fewer cells and collagen fibers, concomitant with a longer inflammatory process, as compared to controls. The lack of saliva induced by submandibulectomy modified the levels of prostaglandin E2 , NO, and TNF-α, and tissue response in the early stages of wound healing compared to controls, and could thus determine alterations in later osteogenic response. Our results allow concluding that hyposialia modulates the parameters of inflammation studied here, and that it is essential for optimal healing. Therefore, these findings provide evidence for the importance of submandibular saliva to final bone socket healing.
Asunto(s)
Tejido de Granulación/patología , Inflamación/patología , Saliva/metabolismo , Alveolo Dental/patología , Cicatrización de Heridas , Xerostomía/patología , Animales , Masculino , Ratas , Ratas Wistar , Saliva/inmunología , Factores de Tiempo , Extracción Dental , Alveolo Dental/inmunología , Factor de Necrosis Tumoral alfa/metabolismo , Xerostomía/complicacionesRESUMEN
BACKGROUND: The aim of this study was to assess the effects of chronic alcohol consumption on periodontitis development in rats. METHODS: Periodontal disease was experimentally induced by lipopolysaccharide (LPS; 2 mg/ml) injections into the gingival tissue around first upper and lower molar's neck, and into the interdental space between first and second molars. This protocol was repeated for 6 weeks on days 1, 3, and 5 of each week. Chronic alcohol consumption was induced by 20% ethanol (EtOH) as the only liquid source during 4 months. RESULTS: Chronic alcohol consumption by itself increased alveolar bone loss and biological mediators of periodontal disease such as prostaglandin E2 (PGE2 ) content on gingival tissue, and inducible nitric oxide synthase activity plus PGE2 content in submandibular gland. Unexpectedly, alcohol consumption did not increase the damage evoked by the proved model of LPS injections for periodontitis induction. CONCLUSIONS: Results suggest 20% alcohol consumption during 4 months generates differential effects on oral health of rats, depending on its pathophysiological state: It would exacerbate the inflammatory condition when periodontal damage is absent, but it would not when damage is installed.
Asunto(s)
Consumo de Bebidas Alcohólicas/efectos adversos , Pérdida de Hueso Alveolar/metabolismo , Pérdida de Hueso Alveolar/patología , Dinoprostona/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Enfermedades Periodontales/metabolismo , Enfermedades Periodontales/patología , Pérdida de Hueso Alveolar/inducido químicamente , Animales , Biomarcadores/metabolismo , Encía/efectos de los fármacos , Encía/metabolismo , Lipopolisacáridos , Masculino , Enfermedades Periodontales/inducido químicamente , Ratas , Glándula Submandibular/efectos de los fármacos , Glándula Submandibular/metabolismo , Factores de Tiempo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
OBJECTIVE: Evidence exists of the anti-inflammatory and immunological properties of endocannabinoids in various tissues; the aim of the present study was therefore to assess the effect of long-term treatment with the synthetic cannabinoid methanandamide (Meth-AEA) on the progression of periodontitis in rats. MATERIALS AND METHODS: Periodontitis was induced by injecting LPS (1 mg/ml) into the gingiva around the neck of the first upper and lower molars, and into the inter-dental space between the first and second molars. This protocol was repeated for 6 weeks on days 1, 3, and 5 of each week. RESULTS: Long-term treatment with topical Meth-AEA (500 ng/ml), applied daily to gingival tissue of rats induced with periodontitis, significantly diminished the alveolar bone loss, measured as the distance between the cemento-enamel junction and the alveolar crest, in both maxillary and mandibular first molars, compared to rats without treatment (P < 0.05). The treatment also reduced the production of some biological mediators of periodontal disease augmented by LPS, such as tumor necrosis factor alpha (from 119.4 ± 9.9 pg/mg protein to 75.1 ± 10.8, P < 0.05) and nitric oxide produced by inducible nitric oxide synthase (from 507.7 ± 107.1 pmol/min/mg protein to 163.1 ± 53.9, P < 0.01). CONCLUSION: These results demonstrate the beneficial effects of treatment with Meth-AEA on gingival tissue of rats with periodontitis.