Protocol to cryopreserve and isolate nuclei from adipose tissue without dimethyl sulfoxide

Cryopreservation injuries involve nuclear DNA damage. A protocol for cryopreserving and isolating adipocyte nuclei is proposed. Adipose tissue samples were directly analyzed (NoCRYO-0h), or stored at -196°C for 7 days without 10% dimethyl sulfoxide (DMSO) (CRYO-WO-DMSO) or with DMSO (CRYO-W-DMSO). To determine the effect of DMSO on cryopreservation treatment, adipose tissue samples were stored at 4°C for 24 h with 10% DMSO (NoCRYO-W-DMSO-24h) and without (NoCRYO-WO-DMSO-24h). Samples were processed in isolation buffer, and nuclear integrity was measured by flow cytometry. The coefficient of variation, forward scatter, side scatter, and number of nuclei analyzed were evaluated. Pea (Pisum sativum) was used to measure the amount of DNA. All groups contained similar amounts of DNA to previously reported values and a satisfactory number of nuclei were analyzed. CRYO-W-DMSO presented a higher coefficient of variation (3.19 ± 0.09) compared to NoCRYO-0h (1.85 ± 0.09) and CRYO-WO-DMSO (2.02 ± 0.02). The coefficient of variation was increased in NoCRYO-W-DMSO-24h (3.80 ± 0.01) compared to NoCRYO-WO-DMSO-24h (2.46 ± 0.03). These results relate DMSO presence to DNA damage independently of the cryopreservation process. CRYO-W-DMSO showed increased side scatter (93.46 ± 5.03) compared to NoCRYO-0h (41.13 ± 3.19) and CRYO-WO-DMSO (48.01 ± 2.28), indicating that cryopreservation with DMSO caused chromatin condensation and/or nuclear fragmentation. CRYO-W-DMSO and CRYO-WO-DMSO presented lower forward scatter (186.33 ± 9.33 and 196.89 ± 26.86, respectively) compared to NoCRYO-0h (322.80 ± 3.36), indicating that cryopreservation reduced nuclei size. Thus, a simple method for cryopreservation and isolation of adipocyte nuclei causing less damage to DNA integrity was proposed.

Swimming exercise at weaning improves glycemic control and inhibits the onset of monosodium L-glutamate-obesity in mice

Swimming exercises by weaning pups inhibited hypothalamic obesity onset and recovered sympathoadrenal axis activity, but this was not observed when exercise training was applied to young adult mice. However, the mechanisms producing this improved metabolism are still not fully understood. Low-intensity swimming training started at an early age and was undertaken to observe glycemic control in hypothalamic-obese mice produced by neonatal treatment with monosodium l-glutamate (MSG). Whereas MSG and control mice swam for 15 min/day, 3 days a week, from the weaning stage up to 90 days old, sedentary MSG and normal mice did not exercise at all. After 14 h of fasting, animals were killed at 90 days of age. Perigonadal fat accumulation was measured to estimate obesity. Fasting blood glucose and insulin concentrations were also measured. Fresh isolated pancreatic islets were used to test glucose-induced insulin release and total catecholamine from the adrenal glands was measured. Mice were also submitted to intraperitoneal glucose tolerance test. MSG-obese mice showed fasting hyperglycemia, hyperinsulinemia, and glucose intolerance. Severe reduction of adrenal catecholamines content has also been reported. Besides, the inhibition of fat tissue accretion, exercise caused normalization of insulin blood levels and glycemic control. The pancreatic islets of obese mice, with impaired glucose-induced insulin secretion, were recovered after swimming exercises. Adrenal catecholamine content was increased by swimming. Results show that attenuation of MSG-hypothalamic obesity onset is caused, at least in part, by modulation of sympathoadrenal axis activity imposed by early exercise, which may be associated with subsequent glucose metabolism improvement.

Maternal low-protein diet during lactation programmes body composition and glucose homeostasis in the adult rat offspring

Previously we have reported that maternal malnutrition during lactation programmes body weight and thyroid function in the adult offspring. In the present study we evaluated the effect of maternal protein restriction during lactation upon body composition and hormones related to glucose homeostasis in adult rats. During lactation, Wistar lactating rats and their pups were divided into two experimental groups: control (fed a normal diet; 23 % protein) and protein-restricted (PR; fed a diet containing 8 % protein). At weaning, offspring received a normal diet until they were 180 d old. Body weight (BW) and food intake were monitored. Serum, adrenal glands, visceral fat mass (VFM) and carcasses were collected. PR rats showed lower BW ( − 13 %;P < 0·05), VFM ( − 33 %;P < 0·05), total body fat ( − 33 %;P < 0·05), serum glucose ( − 7 %;P < 0·05), serum insulin ( − 26 %,P < 0·05), homeostasis model assessment index ( − 20 %), but higher total adrenal catecholamine content (+90 %;P < 0·05) and serum corticosterone concentration (+51 %;P < 0·05). No change was observed in food intake, protein mass or total body water. The lower BW of PR rats is due to a reduction of white fat tissue, probably caused by an increase in lipolysis or impairment of lipogenesis; both effects could be related to higher catecholaminergic status, as well as to hypoinsulinaemia. To conclude, changes in key hormones which control intermediary metabolism are programmed by maternal protein restriction during lactation, resulting in BW alterations in adult rats.

Neonatal hyperleptinaemia programmes adrenal medullary function in adult rats: effects on cardiovascular parameters

Epidemiological studies have shown a strong correlation between stressful events (nutritional, hormonal or environmental) in early life and development of adult diseases such as obesity, diabetes and cardiovascular failure. It is known that gestation and lactation are crucial periods for healthy growth in mammals and that the sympathoadrenal system is markedly influenced by environmental conditions during these periods. We previously demonstrated that neonatal hyperleptinaemia in rats programmes higher body weight, higher food intake and hypothalamic leptin resistance in adulthood. Using this model of programming, we investigated adrenal medullary function and effects on cardiovascular parameters in male rats in adulthood. Leptin treatment during the first 10 days of lactation (8 microg 100 g(-1) day(-1), s.c.) resulted in lower body weight (6.5%, P < 0.05), hyperleptinaemia (10-fold, P < 0.05) and higher catecholamine content in adrenal glands (18.5%, P < 0.05) on the last day of treatment. In adulthood (150 days), the rats presented higher body weight (5%, P < 0.05), adrenal catecholamine content (3-fold, P < 0.05), tyrosine hydroxylase expression (35%, P < 0.05) and basal and caffeine-stimulated catecholamine release (53% and 100%, respectively, P < 0.05). Systolic blood pressure and heart rate were also higher in adult rats (7% and 6%, respectively, P < 0.05). Our results show that hyperleptinaemia in early life increases adrenal medullary function in adulthood and that this may alter cardiovascular parameters. Thus, we suggest that imprinting factors which increase leptin and catecholamine levels during the neonatal period could be involved in development of adult chronic diseases.