Rapid and long-lasting antidepressant-like effects of ketamine and their relationship with the expression of brain enzymes, BDNF, and astrocytes

Ketamine (KET) is an N-methyl-D-aspartate (NMDA) antagonist with rapid and long-lasting antidepressant effects, but how the drug shows its sustained effects is still a matter of controversy. The objectives were to evaluate the mechanisms for KET rapid (30 min) and long-lasting (15 and 30 days after) antidepressant effects in mice. A single dose of KET (2, 5, or 10 mg/kg, po) was administered to male Swiss mice and the forced swim test (FST) was performed 30 min, 15, or 30 days later. Imipramine (IMI, 30 mg/kg, ip), a tricyclic antidepressant drug, was used as reference. The mice were euthanized, separated into two time-point groups (D1, first day after KET injection; D30, 30 days later), and brain sections were processed for glycogen synthase kinase-3 (GSK-3), histone deacetylase (HDAC), brain-derived neurotrophic factor (BDNF), and glial fibrillary acidic protein (GFAP) immunohistochemical assays. KET (5 and 10 mg/kg) presented rapid and long-lasting antidepressant-like effects. As expected, the immunoreactivities for brain GSK-3 and HDAC decreased compared to control groups in all areas (striatum, DG, CA1, CA3, and mainly pre-frontal cortex, PFC) after KET injection. Increases in BDNF immunostaining were demonstrated in the PFC, DG, CA1, and CA3 areas at D1 and D30 time-points. GFAP immunoreactivity was also increased in the PFC and striatum at both time-points. In conclusion, KET changed brain BDNF and GFAP expressions 30 days after a single administration. Although neuroplasticity could be involved in the observed effects of KET, more studies are needed to explain the mechanisms for the drug's sustained antidepressant-like effects.

Rapid and long-lasting antidepressant-like effects of ketamine and their relationship with the expression of brain enzymes, BDNF, and astrocytes.

Ketamine (KET) is an N-methyl-D-aspartate (NMDA) antagonist with rapid and long-lasting antidepressant effects, but how the drug shows its sustained effects is still a matter of controversy. The objectives were to evaluate the mechanisms for KET rapid (30 min) and long-lasting (15 and 30 days after) antidepressant effects in mice. A single dose of KET (2, 5, or 10 mg/kg, po) was administered to male Swiss mice and the forced swim test (FST) was performed 30 min, 15, or 30 days later. Imipramine (IMI, 30 mg/kg, ip), a tricyclic antidepressant drug, was used as reference. The mice were euthanized, separated into two time-point groups (D1, first day after KET injection; D30, 30 days later), and brain sections were processed for glycogen synthase kinase-3 (GSK-3), histone deacetylase (HDAC), brain-derived neurotrophic factor (BDNF), and glial fibrillary acidic protein (GFAP) immunohistochemical assays. KET (5 and 10 mg/kg) presented rapid and long-lasting antidepressant-like effects. As expected, the immunoreactivities for brain GSK-3 and HDAC decreased compared to control groups in all areas (striatum, DG, CA1, CA3, and mainly pre-frontal cortex, PFC) after KET injection. Increases in BDNF immunostaining were demonstrated in the PFC, DG, CA1, and CA3 areas at D1 and D30 time-points. GFAP immunoreactivity was also increased in the PFC and striatum at both time-points. In conclusion, KET changed brain BDNF and GFAP expressions 30 days after a single administration. Although neuroplasticity could be involved in the observed effects of KET, more studies are needed to explain the mechanisms for the drug's sustained antidepressant-like effects.

Antinociceptive and anti-inflammatory activities of a triterpene-rich fraction from Himatanthus drasticus.

Himatanthus drasticus (Mart.) Plumel belongs to the Apocynaceae family and the latex from its trunk bark (Hd) is known as "janaguba milk". This latex is widely used in Northeast Brazil, mainly in the Cariri region, for its gastroprotective, anti-inflammatory, and antitumor properties. The objective of this study was to investigate a triterpene-rich fraction (FJNB) from H. drasticus latex on acute models of nociception and inflammation and to clarify its mechanisms of action. Wistar rats or Swiss mice were subjected to the carrageenan-induced paw edema test or the formalin test, respectively, after the acute oral treatment with FJNB. The inflamed paws from the carrageenan-induced paw edema and formalin tests were processed for histological and immunohistochemical assays, respectively. The results were analyzed by ANOVA and considered significant at P<0.05. FJNB (10 mg/kg) decreased the paw edema by 25% at the 3rd h after the carrageenan injection. Indomethacin, used as reference, inhibited the paw edema by 59% at the same time-point. In the formalin test, FJNB inhibited the 1st phase by 27, 49, and 52% and the 2nd phase by 37, 50, and 67%, at the doses of 1, 5, and 10 mg/kg, respectively. In addition, FJNB significantly inhibited the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the inflammatory cytokine tumor necrosis factor (TNF)-alpha. The histone deacetylase (HDAC) expression and the transcription factor nuclear factor kappa (NF-kB) were also inhibited at the same doses. In conclusion, the FJNB inhibitory actions on iNOS, COX-2, TNF-α, HDAC, and NF-kB could be involved with the drug anti-inflammatory activity.

Antinociceptive and anti-inflammatory activities of a triterpene-rich fraction from Himatanthus drasticus

Himatanthus drasticus (Mart.) Plumel belongs to the Apocynaceae family and the latex from its trunk bark (Hd) is known as "janaguba milk". This latex is widely used in Northeast Brazil, mainly in the Cariri region, for its gastroprotective, anti-inflammatory, and antitumor properties. The objective of this study was to investigate a triterpene-rich fraction (FJNB) from H. drasticus latex on acute models of nociception and inflammation and to clarify its mechanisms of action. Wistar rats or Swiss mice were subjected to the carrageenan-induced paw edema test or the formalin test, respectively, after the acute oral treatment with FJNB. The inflamed paws from the carrageenan-induced paw edema and formalin tests were processed for histological and immunohistochemical assays, respectively. The results were analyzed by ANOVA and considered significant at P<0.05. FJNB (10 mg/kg) decreased the paw edema by 25% at the 3rd h after the carrageenan injection. Indomethacin, used as reference, inhibited the paw edema by 59% at the same time-point. In the formalin test, FJNB inhibited the 1st phase by 27, 49, and 52% and the 2nd phase by 37, 50, and 67%, at the doses of 1, 5, and 10 mg/kg, respectively. In addition, FJNB significantly inhibited the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the inflammatory cytokine tumor necrosis factor (TNF)-alpha. The histone deacetylase (HDAC) expression and the transcription factor nuclear factor kappa (NF-kB) were also inhibited at the same doses. In conclusion, the FJNB inhibitory actions on iNOS, COX-2, TNF-α, HDAC, and NF-kB could be involved with the drug anti-inflammatory activity.

K/DOQI-recommended intact PTH levels do not prevent low-turnover bone disease in hemodialysis patients.

The guidelines proposed by the Kidney Disease Outcomes Quality Initiative (K/DOQI) suggested that intact parathyroid hormone (iPTH) should be maintained in a target range between 150 and 300 pg ml(-1) for patients with stage 5 chronic kidney disease. Our study sought to verify the effectiveness of that range in preventing bone remodeling problems in hemodialysis patients. We measured serum ionized calcium and phosphorus while iPTH was measured by a second-generation assay. Transiliac bone biopsies were performed at the onset of the study and after completing 1 year follow-up. The PTH levels decreased within the target range in about one-fourth of the patients at baseline and at the end of the study. The bone biopsies of two-thirds of the patients were classified as showing low turnover and a one-fourth showed high turnover, the remainder having normal turnover. In the group achieving the target levels of iPTH 88% had low turnover. Intact PTH levels less than 150 pg ml(-1) for identifying low turnover and greater than 300 pg ml(-1) for high turnover presented a positive predictive value of 83 and 62%, respectively. Our study suggests that the iPTH target recommended by the K/DOQI guidelines was associated with a high incidence of low-turnover bone disease, suggesting that other biochemical markers may be required to accurately measure bone-remodeling status in hemodialysis patients.

Vascular calcification: contribution of parathyroid hormone in renal failure.

Hyperphosphatemia is a driving force in the pathogenesis of vascular calcification (VC) and secondary hyperparathyroidism associated with renal failure. To test for the possible contribution of parathyroid hormone (PTH) to cardiovascular calcification, we removed the parathyroid glands from rats but infused synthetic hormone at a supraphysiologic rate. All rats were pair-fed low, normal, or high phosphorus diets and subjected to a sham or 5/6 nephrectomy (remnant kidney). Control rats were given a normal diet and underwent both sham parathyroidectomy and 5/6 nephrectomy. Heart weight/body weight ratios and serum creatinine levels were higher in remnant kidney rats than in the sham-operated rats. Remnant kidney rats on the high phosphorus diet and PTH replacement developed hyperphosphatemia and hypocalcemia along with low bone trabecular volume. Remnant kidney rats on the low phosphorus diet or intact kidney rats on a normal phosphorus diet, each with hormone replacement, developed hypercalcemia. All rats on PTH replacement developed intense aortic medial calcification, and some animals presented coronary calcification. We suggest that high PTH levels induce high bone turnover and medial calcification resembling Mömckeberg's sclerosis independent of uremia. This model may be useful in defining mechanisms underlying VC.