Expression of TRPM8 in sheep reproductive tissues and brain areas important for the expression of reproductive behavior.

The Transient Receptor Potential Melastatin 8 (TRPM8) channel is a temperature-sensitive, calcium permeable ion channel and purported testosterone receptor. To determine how the hormone environment influences the expression of TRPM8 in gonadal tissue and areas of the brain important for reproduction, tissue from western white-faced cross-bred ewes, rams, and gonadectomized males (wethers; n = 6 per group) approximately 6 mo of age were collected. TRPM8 mRNA expression was greater (P = 0.01) in prostate of rams than wethers. Testes had greater (P = 0.004) expression of TRPM8 mRNA than the ovary. Differences in protein expression was similar with the testes having greater (P = 0.007) TRPM8 protein than the ovary. Protein expression did not differ (P = 0.6) in the prostate due to presence (ram) or absence (wether) of the testes. In the brain, TRPM8 varied in the amygdala with rams tending (P = 0.07) to express more mRNA which was reflected in greater (P = 0.04) number of neurons staining positive for TRPM8 in the central amygdala. Differences among ewes and wethers were not detected. This pattern was not observed (P ≥ 0.16) in the hypothalamus or olfactory bulb. To determine if TRPM8 was associated with the expression of ram sexual behavior, brains from rams categorized as high (n = 4) or low (n = 3) sexual activity were collected and blocked. Presence of TRPM8 channels was verified in the amygdala and hypothalamus of rams but was absent in the ventral tegmental area. Numbers of neurons staining positive for TRPM8 did not differ by expression of sexual behavior (P ≥ 0.2) in any area quantified. While expression of TRPM8 is more robust in tissues from intact males, expression of the channel does not appear to be important in the expression of sexual behavior.

A comparison of biochemical and meat quality variables in red deer (Cervus elaphus) following either slaughter at pasture or killing at a deer slaughter plant.

To investigate effects of pre-slaughter handling on blood and muscle biochemistry and venison quality, paddock-shot (n=8) and commercially slaughtered red deer (n=8) were compared. The deer were kept in two larger groups. One stag per group per day was head-shot, exsanguinated, electrically stimulated then transported 150 m to a deer slaughter premises (DSP) for processing. Prior to each slaughter day one of the groups was mustered into a deer yards and six (including two experimental) deer were selected for commercial handling and processing (including electrical stimulation) at the same DSP. Blood samples taken during exsanguination showed higher levels of cortisol, progesterone, glucose, lactate, albumin, creatine kinase, lactate dehydrogenase, aspartate aminotransferase and packed cell volume in the DSP-killed deer compared with the paddock-shot deer (P<0.05). Interpretation of these values indicated that pre-slaughter handling created moderate stress and high levels of muscular exertion or damage, possibly related to antagonism during lairage. However muscle glycogen, pH and meat quality measurements showed only minor, muscle-specific differences between treatments.

Inability of muscles in the obese mouse (ob/ob) to respond to changes in body weight and activity.

The fat-free carcass weight of the obese mouse (ob/ob) is generally less than that of wild-type siblings. The aim of this investigation was to examine the effect of obesity on muscle weights and histochemistry and to determine whether any effects could be eliminated when the obesity was largely prevented or reduced by limiting food intake. For 5 muscles examined the weights were significantly greater (except for biceps brachii) in the wild-type than in obese mice. Although there was a significant correlation between muscle weight (except for soleus) and body weight in the wild-type mice, no such correlation held for the obese mice. No remarkable differences between groups of mice were found in the histochemistry of the biceps brachii and soleus muscles except that fibre sizes were generally smaller in the obese mice. It is concluded that the skeletal muscles of obese mice cannot respond to the increased activity associated with prevented or reduced obesity.

Effects of pituitary dwarfism in the mouse on fast and slow skeletal muscles.

The Snell dwarf mouse exhibits impaired growth of the anterior pituitary resulting in reduced levels of growth hormone and thyroid stimulating hormone. Ten dwarf mice and 10 phenotypically normal littermates were killed at 33 days of age. M. biceps brachii (a predominantly fast muscle) and m. soleus (a relatively slow muscle) were removed from each animal and complete frozen transverse sections obtained. Serial sections were reacted for various enzyme activities in order to identify muscle fibre types. There was no difference in the total number of muscle fibres in m. biceps brachii but a small difference in m. soleus between normal and dwarf mice. There were marked differences in the size of all fibre types between normal and dwarf mice with the largest differences in m. soleus. The percentage of slow oxidative fibres was similar (about 32%) in both groups of mice for m. soleus but there was a marked difference for this fibre type in m. biceps brachii being about 1.5% in normal mice and 8.0% in dwarf mice. This may be related to a difference in levels of thyroid hormone. Nuclear density was very significantly greater in dwarf muscles although total nuclear numbers were less than in normal muscles. These differences are most likely due to growth hormone levels. Differences in nuclear content were much greater in m. soleus than in m. biceps brachii.

Bile acid synthesis and intracellular and extracellular cholesterol concentrations in isolated rat hepatocytes: the effect of dietary cholesterol.

Bile acid synthesis in isolated hepatocytes prepared from rats given 1% cholesterol in the diet and incubated for 1 h in suspension was not increased compared to that in cells from control rats. When the hepatocytes were maintained in monolayer culture for 24 h, however, increased production of bile acid (X2.5) was observed in the cholesterol-fed group. The amount of bile acid synthesised during incubation in suspension was significantly correlated with intracellular unesterified cholesterol levels, but showed no correlation with intracellular esterified or medium cholesterol concentrations after 1 h. Bile acid production in hepatocytes maintained in monolayer culture was also significantly correlated with the intracellular unesterified, but not esterified, cholesterol content. In addition, in this case, there was a significant correlation with the levels of both unesterified and esterified cholesterol found in the medium after 24 h. These results suggest that the amount of cholesterol available to liver cells from extracellular sources has a role in the regulation of bile acid synthesis in cholesterol-fed rats, while the concentrations of esterified cholesterol stored within the cells are not important in this process.

Influence of restricted food intake on brown adipose tissue function in genetically obese mice (genotype, ob/ob).

Measurements were made of cytochrome c oxidase activity and the GDP-binding capacity of mitochondria in brown adipose tissue of genetically obese mice and wild-type siblings, to estimate the thermogenic capacity of the tissue. The binding capacity was decreased in ad libitum fed obese animals compared with wild-type animals. Limited feeding of obese animals to restrict their body weight caused a large increase in the binding capacity of the tissue, which was greater than that in wild-type animals fed either ad limitum or on a limited diet. The decreased binding capacity of brown adipose tissue mitochondria in obese mice appears to be a consequence of ad libitum feeding and therefore not a cause of the obesity. Limit feeding of obese animals also corrected their characteristic hypothermia at low ambient temperature. The large increase in the thermogenic capacity of brown adipose tissue in obese animals, induced by limited feeding, may account for the vital improvement of their thermoregulation. However, close similarities were found between obesity hypothermia and hypothermia induced in wild-type animals by restraint. It is suggested that changes in posture caused by obesity, resulting in increased loss of body heat, may be important in the development of obesity hypothermia. Obese animals fed less than wild-type grained more weight than wild-type animals, indicating that the high thermogenic capacity of their brown adipose tissue did not function to regulate their calorie intake.

The preparation and use of guar bread in diet therapy.

Guar bread rolls were prepared in the hospital diet kitchen from a recipe developed in the Food Science Department of Queen Elizabeth College, using a bread mix to which was added 30 g of guar gum (French, 1982). Four bread rolls per day provided 15 g guar. The dose can be varied as required. The method was satisfactory for home baking providing a regular supply of guar in small quantities can be made available.