Apichaya Niyomchan

NawaTab is a tablet formulation developed from the Nawametho polyherbal formula used in Surat Thani province, Southern Thailand, for the treatment of hyperlipidemia. This study aims at evaluating the acute and subacute toxicity of NawaTab in rats. In the acute toxicity study, NawaTab was evaluated in female rats following the OECD Guideline No. 423. In the subacute toxicity study, NawaTab was tested in both male and female rats following the OECD Guideline No. 407. In the acute toxicity study, no lethal effects or toxic signs were observed during the duration of the study. In the subacute toxicity study, there was no mortality and no abnormality in clinical signs, body weight, food consumption, relative organ weight, and hematological parameters of NawaTab‐treated rats. Significantly increased water consumption by male rats (500 mg/kg BW) and female rats (250, 500, and 1000 mg/kg BW) was observed. In addition, globulin and total cholesterol of female rats (1000 mg/kg BW) significantly increased. These alterations were within normal physiological ranges. Moreover, necropsy and histopathological findings of NawaTab‐treated rats demonstrated no obvious alterations attributable to NawaTab administration. The present study revealed that NawaTab has no significant acute oral toxicological effects. The lethal dose with a 50% mortality rate (LD₅₀) was higher than 5000 mg/kg BW in rats. The subacute oral administration of NawaTab for 28 days did not have any major toxicological effects. Based on this study, NawaTab could be safe to use with caution pending its chronic toxicity study.

A tablet formulation developed from Nawametho decoction (NawaTab), a traditional Thai herbal mixture described in the Worayokasan scripture, has been used clinically for several years in the management of borderline hyperlipidemic individuals. Nevertheless, scientific evidence supporting its claims has never been identified. This study aimed to describe the antihyperlipidemic properties of NawaTab in a well-described model of high-fat diet (HFD)-induced hyperlipidemic rats. Decoction of Nawametho containing equal quantities of Aegle marmelos (L.), Carthamus tinctorius L., Hibiscus sabdariffa Linn., Phyllanthus emblica L., Piper longum L., Piper nigrum L., Terminalia bellirica (Gaertn.) Roxb., Terminalia chebula Retz., and Zingiber officinale Roscoe were prepared. The HFD-fed rats were administered NawaTab for 4 consecutive weeks starting from the ninth week of HFD treatment at a dose of 125mg/kg (p.o.). Anthropometric parameters, serum lipid profiles, lipase activity, and liver and renal functional markers were measured. Histopathological examination of the liver and any steatosis was carried out at the end of this study. Consecutive treatment with NawaTab (125mg/kg/day) in HFD-induced hyperlipidemic rats caused a significant reduction in serum total cholesterol, triglyceride, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol levels. However, at the tested dose, NawaTab failed to prevent the onset of hepatic steatosis and adipose tissue accumulation. No adverse events due to the consumption of NawaTab on liver and kidney function markers were noted. These findings are the first suggestive evidence for the lipid-lowering capability of NawaTab. However, to promote the use of this formulation in the management of borderline hyperlipidemic patients, elucidation of the underlying mechanisms of action, quantification of biological markers, and clinical trials of NawaTab are urgently needed.

It has been known that diabetes mellitus is associated with hyperfunction of the adrenal gland. However, the structural changes of adrenal gland in diabetes have rarely been studied. The aims of this study were to investigate the morphological and microvascular alterations in streptozotocin (STZ)-induced long-term diabetic rats. Twelve male Sprague-Dawley rats were divided into diabetic (n=8) and control (n=4) groups. Each diabetic rat was induced by an intraperitoneal injection of STZ (60 mg/kg) in citrate buffer (pH 4.5). Control rats were intraperitoneally injected with the same amounts of the buffer. These animals were sacrificed at 20 weeks after the injections. The adrenal glands were processed for the morphological and microvascular studies by using conventional light microscopy (LM) and vascular corrosion cast technique combined with scanning electron microscopy (SEM), respectively. In the diabetic group, the cells in zona glomeruloza (ZG) became atrophied and the thickness of this zone was found to be less than that of the controls. In the zona fasciculata (ZF) and zona reticularis (ZR), the hypertrophic cells were investigated in both layers. The degenerated chromaffin and hypertrophic sympathetic ganglion cells in the adrenal medulla were observed. Also some degenerated ganglion cells were found. Additionally, lymphocyte infiltration, macrophages and amyloidosis were found in the adrenal medulla of long-term diabetic rats with renal failure. Under the SEM observation, the luminal diameters of capillaries in the diabetic group were dilated in all zones. In addition, these capillaries in the ZF and ZR were arranged in tortuous courses. This study demonstrates morphological and microvascular changes in the adrenal gland of diabetic rats which are in accordance with the hormonal changes reported by previous investigators.

Summary: The microvasculature of the medulla oblongata in 15 adult Lyle’s flying foxes (Pteropus lylei) was elucidated by using the vascular corrosion cast technique combined with scanning electron microscopy. The study showed that the medulla received the main arterial supply from branches of the vertebrobasilar system. The supplied areas were divided into three groups: ventral, lateral and dorsal groups. All vessel groups gave off circumferential and perforating branches; moreover, these branches anastomosed with one another in two fashions: end‐to‐end and side‐by‐side arrangements. In addition, the ramifications of the branches were L and Y types. The L type was more frequently found than the Y one. The density of capillaries in the nuclei was greater than that in the area of nerve fibres. Numerous arterial sphincters and smooth muscle cells were observed. Furthermore, capillaries in the medulla were of the continuous type, whereas those in the area postrema were fenestrated. The venous drainage system of the medulla was classified into caudal, middle and rostral parts. All of them emptied into both the sigmoid sinus and internal jugular vein. It was concluded that these vascular patterns provide sufficient blood supply to the medulla oblongata of P. lylei when abrupt changes in the position of this bat occurs.