Intact Male Rabbits Research Articles

EFFECTS OF CASTRATION AND SEX HORMONES ON ANTIOXIDANT STATUS AND SOME BIOCHEMICAL PARAMETERS OF MALE RABBITS EXPOSED TO OXIDATIVE STRESS

The present study was aimed to investigate the effect of estrogen and testosterone as antioxidants and their ability to prevent the effect of H2O2-induced oxidative stress and their reflections on blood parameters and antioxidant status of male rabbits. 72 adult male rabbits were divided randomly into 12 groups (6/group), 1st group: Intact, 2nd group: Intact-H2O2, 3rd group: Castrated, 4th group: Castrated-H2O2, 5th group: Intact-H2O2-Testosterone, 6th group: Castrated-H2O2-Testoterone, 7th group: Intact-H2O2-Estrogen, 8th group: Castrated-H2O2-Estrogen, 9th group: Intact-Testosterone, 10th group: Castrated-Testosterone, 11th group: Intact-Estrogen, 12th group: Castrated-Estrogen, treatments continued for 4 weeks. Results showed that castration increased significantly GSH, TAC, TG, HDL-C levels, and significantly decreased MDA, AST, ALT levels. Treatment with H2O2 caused a significant decrease in the levels of GSH, TAC, HDL-C, total proteins, and a significant increase in the levels of MDA, cholesterol, TG, LDL-C, ALT, AST compared to untreated group. On the other hand, estrogen treatment improves TAC, GSH and lipid profile and reduce MDA significantly as compared with testosterone treatment and control group. In regard to interaction effects, castration without H2O2- estrogen treatment reduces the stress as represented by the reduction of MDA, risk index, ALT and elevate the GSH and TAC levels. These results indicate that castration and estrogen treatment of castrated and intact male rabbits reduce stress effects and improve the lipid profile and some immunological measures.

Increased mRNA Expression Levels of Nrf2 and TSPO Genes as a Markers of Brain Injury-induced by Aflatoxicosis and Ameliorated by Arginine Administration in Male Rabbits

L-protective arginine's function in adult male rabbits administered Aflatoxin B1 and l-arginine is the focus of this investigation. Four equal groups of 20 intact male rabbits were proposed: control group receiving distal water, (G1) receiving Aflatoxin B1 (oral dose of 4μg / animal.), (G2) receiving l-arginine (300 mg/animal orally) and (G3) receiving both Aflatoxin B1 and l-arginine. As compared to other groups, the Aflatoxin group (G1) had a large increase in reverse transcription (mRNA) of Nrf2 and Tspo genes (G2 and G3). In addition, we found that the arginine group had lower amounts of Nrf2 and TSPO mRNA than the Aflatoxin group (G1). According to these findings, Arginine protects the brain from Aflatoxin B1-induced oxidative damage.

Selenium Enriched Yeast Modifies the Effects of Methandienone in Male Rabbits on the HPA Axis and Adrenal Gland Oxidative Stress

The aim of this study was to investigate the changes caused by anabolic androgenic steroids (methandienone) in the hypothalamic adrenal axis (HPA) and oxidative status in adrenal glands and a protective role role by using organic selenium (high-selenium yeast) in adult male rabbits which treated with Methandienone in combination with selenium. A total of 20 intact male rabbits were divided into four equal groups (n = 5 for each group):a control group receiving distilled water, the AAS group (T1) receiving Methandienone (oral dose of 0.35 mg / kg.B.W.),the selenium group (T2) receiving high-selenium yeast (3 μg/ kg B.W orally)and the combination group (T3) getting both methandienone and selenium. The dosing every day for 60 days. . The hormones β-endorphin, ACTH and cortisone were measured in serum during two periods, 30 and 60 days of the experiment and the expression levels of Nuclear factor erythroid-2 and related factor-2 (Nrf2) and Translocater protein (TSPO) genes were measured in adrenal gland. a significant increase in beta-endorphin and ACTH and a decrease in cortisone were found in both 30 and 60 day periods in the AAS group (T1) compared with another groups (control, T2 and T3). On the other hand, T3 group shows a decrease in serum β-Endorphin and ACTH and no significant changes in cortisone in both periods .These changes were a compared with to AAS group. Moreover, there is a significant increased in revers transcription (mRNA) of Nrf2 factor and TSPO genes in AAS group(T1) as compared with other groups (T2 and T3). In addition, we observed a significant decrease in levels of Nrf2 and TSPO mRNA in the selenium-yeast group compared to the AAS group (T1). In conclusion, these results showed that organic selenium (high selenium yeast) has a positive effect (protective role) against oxidative damage to the adrenal gland caused by AAS with no effect on the adrenal steroidogenesis, which are affected by AAS.

Effects of estradiol benzoate injection to intact and castrated male rabbits on LH, FSH, testeosterone and prostate tissues

Objective: This study was conducted to investigate the effects of estradiol benzoate injection to intact and castrated male rabbits on LH, FSH, testosterone and prostate tissue. Materials and methods: A total of 72 mature male rabbits were used in this study. The rabbits were randomly divided into two groups (36 intact and 36 castrated) and each group was further divided into four sub-groups. The rabbits of each subgroup were injected estradiol benzoate dosed at 0, 40, 80 and 120 µgm/rabbit, through intramuscular (IM) route, on each alternative day over a period of 30 days. The levels of LH, FSH, and testosterone were measured in serum samples. Prostate tissue samples were taken from each sub-groups, histological examination was done. Results: The mean serum levels of LH and FSH were not affected by injection of estradiol benzoate in all intact and castrated rabbits sub-groups (P>0.05). However, the results of testosterone levels were showed insignificant increase in all intact and castrated male rabbits sub-groups, except the intact male rabbit sub-group that received estradiol benzoate at 120 µg/rabbit (P

Inguinal-Scrotal Urinary Bladder Hernia in an Intact Male Domestic Rabbit (Oryctolagus cuniculus)

An 8-year-old intact male dwarf rabbit (Oryctolagus cuniculus) was presented with a 2-month history of unilateral scrotal swelling. The external physical examination of the rabbit patient confirmed the severe, unilateral, fluid-filled scrotal distention. Radiographic images of the effected scrotum revealed a soft tissue swelling in the area of the left testicle, and the absence of the urinary bladder in the caudal abdomen. Ultrasonography verified the presence of a fluid-filled mass in the scrotum, enveloping the left testicle. A fine-needle aspiration of the scrotal mass yielded urine, thus a diagnosis of a nonreducible herniation of the urinary bladder into the scrotum was made. An inguinal herniorrhaphy was performed, and the bladder was successfully reduced into the abdominal cavity. A bilateral routine castration and left scrotal ablation were also performed. Two months after surgery no recurrence was noted, and the patient had normal urinary function. Inguino-scrotal bladder herniation is rare in both humans and animals. Male rabbits are predisposed to inguinal and scrotal hernias because their inguinal rings remain open throughout life. Herniation of the urinary bladder should be considered as a differential diagnosis when intact male rabbits are presented with unilateral scrotal swelling.

The Stimulatory Effect of Corticotrophin on Testicular Testosterone Release in Male Rabbits

Intravenous injection of 1-24 ACTH synthetic analogue (10 micrograms/kg body weight 1-24 ACTH) via permanent indwelling jugular catheters to intact male rabbits, resulted in a rapid rise of plasma corticosteroid (C) and plasma testosterone (T) levels. Mean C levels were significantly elevated during the period between 10 and 100 min after ACTH administration whereas mean T concentrations showed a significant rise at 20 min after the 1-24 ACTH administration. On the other hand a significant suppression of plasma T levels was observed 120 min p.i., indicating a biphasic effect of 1-24 ACTH on plasma T levels. Castrated animals reacted to 1-24 ACTH with mean C levels, comparable to concentrations in intact rabbits, whereas their lowered plasma T concentrations showed no changes. When 1-24 ACTH was administered to intact animals 96 h after pretreatment with HCG, plasma T levels were significantly elevated at 20 min after 1-24 ACTH injection whereas a second HCG injection was ineffective in modifying T concentrations. From these results we concluded, that exogenously applied 1-24 ACTH can effectively stimulate the testicular T release in adult male rabbits and that such release is independent of the LH receptors in Leydig cells.

Encephalitis in a rabbit caused by human herpesvirus-1

An 8-month-old sexually intact male rabbit was examined because of a 2-day history of anorexia, epiphora of the left eye, bruxism, hypersalivation, and ataxia. Physical examination of the rabbit revealed bilateral conjunctivitis, hypersalivation, and severe signs of CNS dysfunction such as incoordination, intermittent myoclonic seizures, and opisthotonus. Results of hematologic and serum biochemical analyses revealed only lymphopenia, a relative monocytosis, and an increase in serum activity of creatine phosphokinase and serum concentration of total protein. Serum antibodies against Encephalitozoon cuniculi and Toxoplasma gondii were not detected. Despite IV administration of crystalloid fluids and treatment with antimicrobials, vitamin B complex, nutritional support, and prednisolone, the condition of the rabbit deteriorated; it was euthanized 7 days after admission. Histologic evaluation of brain tissue revealed lesions characteristic of severe, diffuse, nonsuppurative meningoencephalitis and a few large, eosinophilic, intranuclear inclusion bodies in neurons and glial cells. The DNA of human herpesvirus-1 was detected in the nuclei of glial cells, lymphocytes, and neurons by means of in situ hybridization. The rabbit's owner, who reported having had a severe labial and facial herpesvirus infection 5 days before the onset of clinical signs in the rabbit, was suspected to be the origin of infection for the rabbit. Human herpesvirus-1 may be transmissible from humans to rabbits, and infection with this virus should be considered as a differential diagnosis in rabbits with CNS signs of disease.

Possible involvement of norepinephrine transporter activity in the pulsatility of hypothalamic gonadotropin-releasing hormone release: influence of the gonad.

Pulsatile secretion of hypothalamic gonadotropin-releasing hormone (GnRH) is suppressed by alpha-adrenergic antagonists in ovariectomized (OVX) rabbits, thus suggesting that initiation of GnRH pulses requires the presence of norepinephrine (NE) stimulation. Terminals of NE neurons are located in proximity with GnRH cells in the hypothalamus, including the arcuate nucleus-median eminence (AME) region. Synaptic NE molecules may be catabolized or transported back to NE terminals (i.e. reuptake) via specific NE transporter proteins (NET). Thus, the amount of synaptic NE acting on GnRH cells is a function of the rate of NE release, metabolism and reuptake. Hypothetically, the rise and fall of a GnRH pulse may be associated with the similar fluctuations of synaptic NE release and/or NET activity. To test this hypothesis, we examined the effects of AME administration of desipramine (DMI, a specific NET blocking drug) on GnRH release. First, we delivered 0.2-10 mM doses of DMI continuously for 1 h via an AME microdialysis (microD) system into intact male rabbits. We found that each AME-DMI infusion, between dosages of 1 mM and 10 mM, stimulated a GnRH pulse, and that the size of these GnRH pulses were proportional to the dosage of DMI. To confirm the specificity of DMI on NET, we measured catecholamine content in microD samples by HPLC. The temporal (60 min) DMI induced a pattern of NE release that included a rising limb within the first 20-30 min; although NE returned to baseline values within the period of DMI treatment. Neither epinephrine nor dopamine levels were changed by DMI. Second, a median dose of DMI (5 mM) was given by microD for 60 min in four separate rabbit models: gonadal intact females (F-INT), intact males (M-INT), gonadectomized females (F-GDX) and castrated males (M-GDX). Individual microD samples were measured for NE and GnRH. Regardless of gender or gonadal status, 5 mM of DMI concomitantly induced a pulse-like release of NE and GnRH. Furthermore, the response of GnRH to DMI was greater in GDX rabbits than in INT animals of both genders. Third, we administered DMI (5 mM) for 30 min via a push-pull perfusion (PPP) system during four repeated 90 min intervals, in either F-INT or ovariectomized (F-GDX) females, and measured GnRH in PPP samples. In both F-INT and F-GDX, each DMI challenge induced a GnRH pulse. In F-INT, all sequential DMI-induced GnRH pulses were nearly equal in size. In contrast, in F-GDX, the first DMI-induced GnRH pulse was greater than subsequent ones. Collectively, these observations are consistent with the concept of noradrenergic regulation of pulsatile GnRH release, and we conclude that the temporal activity of NET may be an integral part of the mechanism by which GnRH pulses operate.

Active immunization of rabbits against progesterone: Increase in hormone levels, and changes in metabolic clearance rates and in genital tract tissues

11α-Hemisuccinyl progesterone was coupled to rabbit serum albumin and injected into intact male rabbits, and into intact ovariectomized female rabbits, for a period of 52 weeks. The ovariectomized females and the intact males showed better immune responses than the intact females. Specificity of the antisera was tested against both progesterone and the carrier protein, and against 19 other selected steroids. Antibody titres and serum levels of progesterone in all groups, and testosterones in the males, showed characteristic changes with a first maximum 12–18 weeks after the beginning of immunization, a decrease despite booster injections and a second increase after 35–40 weeks. Hormone levels were 5–12 times higher by the end of immunization than before. High antibody titres were correlated with decreased metabolic clearance rates for progesterone, reflecting the binding of the steroid to the antibody. Increased production rates of progesterone in the immunized females and of testosterone in the immunized males showed that the antibody-bound hormone was not available for feedback control. Absence of primordial follicles, hyperplasia of the Leydig cells, decreased spermatogenesis and involution of the seminal vesicle epithelium were interpreted as direct or indirect effects of the removal of free progesterone.

Gonadotrophin secretion and pituitary responsiveness to LHRH in castrated and intact male rabbits exposed to different photoperiods.

Adult male wild rabbits were exposed to at least 16 weeks of 16L:8 D before experiments began. Plasma LH and FSH concentrations increased significantly (P less than 0.001) when rabbits were castrated in 16L:8D but declined when rabbits were transferred to 8L:16D. Concentrations had returned to normal for castrated rabbits in 16L:8D by 74 days after the start of the 8L:16D treatment. Treatment of intact male rabbits with an injection of LHRH before and after transfer to short daylengths caused a transient increase in plasma LH which lasted 50-80 min and this produced a concomitant rise in plasma testosterone. The daylength change had no effect on this response even though testicular size declined after the transfer to short daylengths. Rabbits moulted in response to exposure to 8L:16D. This suggests that hypothalamic activity responds to photoperiod and that changes in pituitary responsiveness to LHRH and steroid negative feedback are unimportant.

Sexual dimorphism in the motor mounting pattern of the New Zealand white rabbit: Steroid regulation of vigor and rhythmicity of pelvic thrusting

The motor mounting patterns of male and female New Zealand white rabbits were analyzed by means of an accelerometric technique and frequency analysis. Clear behavioral dimorphism was noted in the motor mounting pattern. Pelvic thrusting by males was periodic while that performed by females lacked rhythmicity. Thrusting in males was more vigorous than in females. Ovariectomy markedly decreased the incidence of mounting behavior. Testosterone propionate (TP, 5 mg daily for 1 month), restored mounting in all ovariectomized rabbits. TP stimulated the vigor of thrusting and induced a rhythmic mounting pattern in many cases similar to that displayed by intact male rabbits, i.e., thrusting frequency 13–16 per second. Estradiol benzoate (10 μg daily for 1 month), elicited mounting in three of the seven rabbits tested. Pelvic thrusting in these rabbits was often highly synchronous showing a frequency higher (18 to 21 thrusts per second) than that displayed by male rabbits. The results suggest the following conclusions: (a) the behavioral dimorphism in mounting observed in rabbits is due to variations in the secretion of sex steroids by the adult gonads rather than to differences in the organization of the neural substrate of mounting; (b) gonadal steroids influence directly or indirectly the neural structures involved in some characteristics of pelvic thrusting, i.e., rhythmicity and vigor.

RELATION OF THE CHANGES IN TESTICULAR STRUCTURE INDUCED IN THE RABBIT BY ESTROGENIC SUBSTANCE TO RESISTANCE AGAINST SYPHILIS

IN SEEKING the nature of the factors underlying the sexual differences in immunity to syphilis, we undertook an experimental study of the disease in male rabbits feminized by prolonged administration of an estrogenic substance (1, 2). This substance, prepared from a butyl alcoholic extract of human pregnancy urine, was capable of inducing estrous effects in ovariectomized rats. When given to adult male rabbits, there resulted a series of anatomical changes, including partial metamorphosis of the external genitalia, and the development of certain female secondary sex characters (1, 3). When the testis was the site of inoculation, the feminized rabbits responded with a milder form of syphilis than the sexually intact male rabbits. This was true of both the primary testicular and the generalized metastatic phenomena of the disease.