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The present study was aimed at characterizing the effects of low-protein malnutrition (6% casein) on the circadian rhythm of drinking behavior and on suprachiasmatic nuclei immunohistochemistry in Sprague-Dawley rats. Recordings were started at 30 days of age under a 12:12-h light-dark (LD) cycle. At age 150 days, recordings were continued under constant dim red light, and finally the latency to entrain to complete and skeleton photoperiods was established. At the end of the recordings rats were processed for histological analysis. Compared with their controls, malnournished rats exhibited 1) splitting of rhythmicity under LD that 2) condensed to one component in constant dim red light, 3) delayed entrainment to skeleton photoperiod, and 4) precocious entrainment under complete photoperiod. Immunohistochemical analysis showed mainly a decrease in the immunohistochemical detection of vasoactive intestinal polypeptide and glial fibrillar acid protein cells in malnourished animals. These results indicate that in malnourished rats there is a decrease 1) in the coupling force among the oscillators and 2) in the strength of the phase lock between the oscillators and the light-dark cycle.

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The rat is one of the most frequently selected animals for studies in urological research, including experimentally-produced testicular torsion (Dokucu et al. 2000), orchiectomy (Ashby & Lefevre 2001) and cryptorchidism (Vigueras et al. 1999).Testicular torsion, or the torsion of the spermatic cord, is a surgical emergency in humans that causes testicular injury and subfertility. It is generally accepted that unilateral testicular torsion causes contralateral testicular deterioration and results in diminished fertility (Bartsch et al.

It is thought that the degeneration of germ cells associated with an increase in the temperature due to cryptorchidism involves oxidative stress. α-Tocopherol is a powerful antioxidant that prevents oxidation of polyunsaturated fats found in membranes and stabilizes peroxyl radicals. For this reason we were interested in determining the role of α-Tocopherol using experimental cryptorchidism, followed by orchidopexia in neonatal rats. Eighty-four, 10-day-postpartum (dpp) male rats (Wistar strain) were used and divided into 7 groups: healthy control, sham with α-Tocopherol treated with 30 or 100 mg/kg doses, sham vehicle, cryptorchidism treated with α-Tocopherol at 30 or 100 mg/kg doses and cryptorchidism vehicle. Cryptorchidism was surgically induced at 10 dpp. At 25 dpp the animals were treated with α-Tocopherol and the vitamin vehicle. Lipoperoxidation and testicular morphology was determined in half of the animals at 40 dpp (short term). The remaining animals underwent orchidopexia and fertility was determined at 90 dpp. Testicular morphology was determined at 120 dpp (long term) in these animals. A significant reduction of lipoperoxidation was observed in the cryptorchid group treated with α-Tocopherol compared to the untreated cryptorchid group, in addition to short-term histological alterations. At long term, we observed an increase in the area and maturation of the seminiferous epithelium, a decrease in apoptosis and histological alterations and an increase in fertility from α-Tocopherol treatment. α-Tocopherol treatment decreased lipoperoxidation, possibly stabilizing free radicals produced during cryptorchidism, reducing morphological testicular alterations and favoring fertility.

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In spite of the widespread use of rats in gastrointestinal research, there is a lack of information on the qualitative and quantitative histological characteristics. Therefore, a study was performed in 69 male Wistar rats with ages ranging from one day to one year old. The features studied included: height and number of villi in the duodenum, jejunum and ileum, and depth and number of crypts in the duodenum, jejunum, ileum, colon and rectum. Morphometric observations were expressed in a mathematical logarithmic curve that showed a normal pattern of intestinal growth for each intestinal level. The number of villi in the small intestine decreased from 1 to 3S days of age, whereas the other intestinal parameters all increased during the same period. After 3S days the rates of increase or decrease were lower. The quantification of these intestinal changes provides a new complementary pattern as a reference for research as indicators of normality or malfunction in the rat intestine. Keywords Intestine; histology; postnatal development; villi; cryptsThe intestine undergoes an array of adaptative changes during postnatal development, similar to other organs. In the intestinal mucosa, these changes occur largely in structures related to the exchange and absorption processes, such as villi, crypts, enterocytes and microvilli. The morphological and biochemical changes that occur in the human intestinal mucosa under different physiological and pathological conditions, have been studied using the rat as a model system. These include colitis IRachmilewitz et al. 1993), ulcers (Matsumoto et al. 1994),' enteritis (Pothoulakis et al. 1993