Immunophenotyping of Rabbit Testicular Germ and Sertoli Cells Across Maturational Stages.

During testicular maturation, both Sertoli cells (SCs) and germ cells (GCs) switch from an immature to a mature immunophenotype. The reexpression of markers of immaturity in adults has been reported in cancer and in other testicular pathologies, in men as well as in animal species. Naturally affected with testicular cancer, rabbits have long been used in human reproductive research, but reports on the expression of testicular cell markers in this species are few and data about the immunophenotype of normal postnatal SCs and GCs are lacking. The aim of this study was to investigate the immunophenotype of SCs and GCs in the rabbit, from neonatal to adult age, using the antibodies anti-Müllerian hormone (AMH), vimentin (VIM), CKAE1/AE3 (cytokeratins [CKs]), desmin (DES), inhibin alpha (INH-α), placental alkaline phosphatase (PLAP), and periodic acid-Schiff (PAS) staining. In SCs, VIM was constantly expressed, and AMH and CKs expression was limited to neonatal and prepubertal age, whereas DES, INH-α, PLAP, and PAS were constantly negative. GCs were negatively stained for PLAP, PAS, and for the other markers. Results revealed analogies with human testicular immunophenotype, suggesting that rabbits could represent a potential experimental model for the study of human testicular pathology.

[Cardiocirculatory and respiratory reflexes of muscular origin during prolonged experimental dynamic exercise. Effects of sectioning of the sino-carotid and aortic nerves and bilateral vagotomy]. / Riflessi cardiocircolatori e respiratori di origine muscolare in corso di esercizio dinamico sperimentale prolungato. Effetti della sezione dei nervi seno-carotidei ed aortici e della vagotomia bilaterale.

In anesthetized rabbits we have evaluated the effects of denervation of sino-aortic areas and vagotomy on the reflex cardiorespiratory responses during 2 min of contractions of gastrocnemius muscle induced by electrical stimulation of tibial nerve. The following parameters were examined: blood pressure (BP), heart rate (HR), respiratory frequency (f), tidal volume (Vt) and pulmonary ventilation (Ve) while arterial pH, pCO2 and pO2 and end-tidal CO2 (petCO2) were monitored. During steady state of rhythmic contractions we observed a decrease of BP, a slight decrease in HR and marked rise of Ve due to an increase of f with a slight increase of Vt. The sectioning of carotid-sinus, aortic and vagus nerves does not substantially modify the cardiorespiratory responses to muscular exercise; all the responses are abolished from the sectioning of somatic nerves in exercising limbs. The importance of the role of the peripheral nervous control by muscles (peripheral drive) is confirmed in the regulation of cardiorespiratory participation in motory activity, also in the steady state phase of muscular exercise in which components of a chemometabolic or hemodynamic nature could be more effective.

[Study of the interactions of atrial natriuretic peptides with the autonomic nervous system. Effects on cardiocirculatory and respiratory reflexes caused by activation of chemosensitive muscle receptors]. / Studio delle interazioni dei peptidi natriuretici atriali con il sistema nervoso autonomo. Effetti sui riflessi cardiocircolatori e respiratori da attivazione di recettori chemosensibili muscolari.

In order to verify the hypothesis that possible interactions with the autonomic nervous system may contribute to the cardiovascular effects of atrial natriuretic factor (ANF), 9 rabbits were anesthetized to study the effect of the infusion of synthetic human ANP (2 mcg/kg in bolus followed by 0.2 mcg/kg/min for 20 min iv) on the reflex responses induced by intra-arterially injected BK (250 ng) and hypertonic NaCl (10%) or glucose (40%). The infusion of ANP provoked a decrease in systolic (SBP, 14%) and diastolic (DBP, 8%) pressure without any significant changes in heart rate (HR). The injection of BK and hypertonic NaCl into femoral arteries carried out during ANP infusion produced cardiorespiratory response patterns similar to those observed in control conditions. After injecting BK, a fall in SBP (25%), DBP (50%) and HR (16%), and an increase in breathing frequency were observed. After injecting NaCl, an increase occurred in SBP (20%), DBP (25%), HR (10%) and in depth of breathing. In the present experimental conditions, ANP has not been found to be capable of significantly interfering with the reflex pattern of cardiorespiratory responses either from the inhibition or activation of the sympathetic nervous system induced by chemical stimulation of muscle receptors.

Cardiorespiratory reflexes from muscles during dynamic and static exercise in the dog.

Cardiorespiratory reflex responses during the initial phase of dynamic and static contraction of hindlimb muscles were studied in anesthetized dogs. Muscle contractions were elicited by stimulating the femoral and gastrocnemius nerves at 3 and 100 Hz with the intensity of 2.0-2.5 times the motor threshold for a 20-s period. Rhythmic contractions caused a decrease in arterial pressure (Pa) and heart rate (HR) and increased pulmonary ventilation (VE) by increasing frequency (f) without significantly changing VT. Tetanic contractions provoked an increase in Pa and HR and a hyperpnea resulting from a rise in both f and VT. Similar responses were also obtained in anesthetized dogs with carotid sinuses denervated and cervical vagi cut. The abrupt increase in VE at the start of both types of exercise was not associated with immediate significant decreases in end-tidal CO2 values. These two patterns of cardiocirculatory and respiratory responses were closely similar to those reported in anesthetized rabbits in previous studies. Both patterns of responses were reflexes initiated by activation of muscle receptors verified by interrupting the afferents from the contracting muscles. It is concluded that, during dynamic and static work, two distinct muscular reflex mechanisms might exert their drives, related to the muscular metabolic rate, on the circulatory and respiratory function.