MORPHOMETRIC AND BIOCHEMICAL EVALUATION OF RAT PROSTATE AND SEMINAL-VESICLE FOLLOWING CHEMICAL SYMPATHECTOMY WITH GUANETHIDINE

Selective chemical sympathectomy of the internal genital organs of adult male rats was undertaken by chronic treatment with low doses of guanethidine. Biochemical and morphometric methods revealed that removal of sympathetic innervation prevents fructose secretion in the prostate and seminal vesicle, in addition to promoting reduced efficiency of delivery by the latter.

THE HYPOPHYSEAL-TESTICULAR AXIS AND SEX ACCESSORY-GLANDS FOLLOWING CHEMICAL SYMPATHECTOMY WITH GUANETHIDINE OF PRE-PUBERTAL TO MATURE RATS

Selective chemical sympathectomy of the internal sex organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Plasma testosterone and luteinizing hormone and the intratesticular level of testosterone were determined. The weight and fructose content of seminal vesicle and ventral prostate were also investigated. The results showed that sympathetic innervation is related to the control of the hypophyseal-testicular axis as well as to the growth and potential secretory activity of the male sex accessory glands.

CHEMICAL SYMPATHECTOMY BLOCKS ANDROGEN BIOSYNTHESIS DURING PREPUBERTY

Twenty-one-day old male Wistar rats were injected subcutaneously with guanethidine (GUA) at doses of 5 and 10 mg kg(-1) day(-1) for 20 days. Animals were sacrificed by decapitation during the prepubertal (41 days of age) and early-pubertal (51 days of age) periods of sexual development. The testes were collected, frozen in liquid N-2 and stored at -70 degrees C until determination of testicular progesterone (P): androstenedione (A) and testosterone (T). Higher levels of P (2.18 +/- 0.24 ng/g. control = 1.24 +/- 0.16 ng/g) associated with decreased levels of androgens (A = 0.26 +/- 0.06 ng/g and T = 2.05 +/- 0.19 ng/g; control = 1.86 +/- 0.76 ng/g and 8.48 +/- 1.16 ng/g, respectively) were observed in 10 mg GUA-treated rats of prepubertal age, while only P levels (3.12 +/- 0.51 ng/g control = 1.73 +/- 0.27 ng/g) were increased in rats of early pubertal age. It is important to note that in 41-day old male rats both 5 and 10 mg were effective in decreasing testicular concentration of testosterone. These results suggest that the sympathetic innervation of the testis is involved in the modulation of androgen biosynthesis, acting through a selective step in the steroid biochemical pathway during the pubertal process and that under the conditions employed the blockage in androgen biosynthesis in the prepubertal stage of sexual maturation is dependent on the dose of GUA.

Morphometric evaluation of the rat testis, epididymis and vas deferens following chemical sympathectomy with guanethidine

Selective chemical sympathectomy of the internal sex organs of adult male rats was undertaken by long term administration of low doses of guanethidine. The spermatogenic activity of the testis was unaffected by treatment. Examination of the vas deferens using morphometric methods revealed a marked increase in luminal area in contrast to a decrease in muscle layer area and in epithelial height. This is morphological evidence of sperm accumulation caused by a disorder in ductal contractile activity. No structural changes were observed in the epididymis. However, the concentration of spermatozoa in the sperm suspension stored in the cauda epididymidis was significantly increased in denervated rats. This result is discussed in terms of a sympathetic control of resorption mechanisms in the epididymis.

Effects of guanethidine-induced sympathectomy on the spermatogenic and steroidogenic testicular functions of prepubertal to mature rats

Selective chemical sympathectomy of the internal genital organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Sympathetic denervation caused an increase in intratesticular progesterone levels in prepubertal and early pubertal rats in addition to a decrease in androstenedione and testosterone levels in prepubertal animals, thus indicating a decrease in the conversion of progesterone into androgen, probably by blocking the steroidogenic enzymatic pathway at the 17 alpha-hydroxylase/17,20 desmolase level. A lower degree of testicular maturation, probably related to reduced androgen activity, was observed in prepubertal and early pubertal sympathectomized rats. Concentration of spermatozoa, on the other hand, was increased in the enlarged cauda epididymidis of late pubertal and mature denervated animals. This result is discussed in terms of the impairment of epididymal mechanisms of seminal emission, fluid resorption and spermatozoal disposal.

alpha(1)-Adrenoceptors in proximal segments of tail arteries from control and reserpinised rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Catecolaminas do aparelho reprodutor de ratos após simpatectomia química: metodologia analítica e comparação entre as variedades Wistar e Sprague-Dawley

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A novel nonneuronal catecholaminergic system: exocrine pancreas synthesizes and releases dopamine.

Cells of the exocrine pancreas produce digestive enzymes potentially harmful to the intestinal mucosa. Dopamine has been reported to protect against mucosal injury. In looking for the source of dopamine in the small intestine, we found that the duodenal juice contains high levels of dopamine and that the pancreas itself has a high dopamine [and dihydroxyphenylalanine (dopa)] content that does not change significantly after chemical sympathectomy. Furthermore, we were able to demonstrate tyrosine hydroxylase (TH) activity in control pancreas as well as in pancreas from rats after chemical sympathectomy. Immunostaining and in situ hybridization histochemistry confirmed both the presence of TH, dopamine, and the dopamine transporter, and the mRNAs encoding TH and dopamine transporter, and the presence of both types of vesicular monoamine transporters in the exocrine cells of the pancreas. Since there are no catecholaminergic enteric ganglia in the pancreas, the above results indicate that pancreatic cells have all the characteristics of dopamine-producing cells. We suggest that the pancreas is an important source of nonneuronal dopamine in the body, and that this dopamine has a role in protecting the intestinal mucosa and suggests that dopamine D1b receptor agonists might be used to help mucosal healing in the gastrointestinal tract.

Chemical lumbar sympathectomy in plantar hyperhidrosis

Plantar hyperhidrosis can cause great changes to an individual's quality of life. We described a case successfully treated by the minimally invasive method of percutaneous injection of 7.0% phenolic solution into the lumbar sympathetic chains.

Fertility of rat epididymal sperm after chemically and surgically induced sympathectomy

Guanethidine, a chemical that selectively blocks sympathetic noradrenergic neurons, was used to investigate the role of sympathetic innervation in the fertility of rat epididymal sperm, using both natural mating and in utero insemination protocols. This animal model correlates, at least in part, with spinal cord injury (SCI) in men. Adult male rats were treated daily by i.p. injections, for 21 or 42 days, with 0 or 6.25 mg/kg guanethidine. To compare the effects of guanethidine-induced sympathectomy with those following surgically induced sympathectomy, the inferior mesenteric ganglion and the proximal hypogastric nerves were removed in another group of rats. Both chemically and surgically induced sympathectomy increased the weight of the epididymis and seminal vesicles/coagulating glands as well as the number and the transit time of cauda epididymal sperm. Neither serum testosterone levels nor LH was affected by treatment with guanethidine. Using natural mating, no litters were produced by guanethidine-treated rats. Chemically denervated rats failed to produce copulatory plugs or ejaculate into the uterus. However, distal cauda epididymal sperm from chemically or surgically denervated rats displayed normal fertilization ability (80%) using in utero inseminations. In addition, the sperm of denervated rats did not show abnormal sperm chromatin structure using an assay that detects DNA damage. We conclude that sympathectomy delays the transit of sperm through the cauda epididymidis and produces ejaculatory dysfunction but does not compromise sperm quality in the distal cauda epididymidis. Moreover, these data provide compelling evidence that there is no association between the prolonged transit time of sperm within the epididymis, i.e., pre-ejaculatory sperm aging, and the fertility of those sperm, which has important implications for artificial insemination using sperm from men with SCI.

Rat epididymal sperm quantity, quality, and transit time after guanethidine-induced sympathectomy

Guanethidine, a chemical that selectively abolishes peripheral noradrenergic nerves, was used to investigate the role of sympathetic innervation in the maintenance of epididymal sperm quantity and quality. Four groups of 10 adult male rats each were treated daily for 21 days, by i.p. injections, with either 0 (saline vehicle), 6.25, 12.5, or 25 mg/kg guanethidine. Norepinephrine content was reduced to undetectable levels in the cauda epididymidis in all guanethidine groups after 3 wk of treatment and was reduced to 7.4% of the control values after 1 wk of 6.25 mg/kg treatment. While body weight gain was significantly decreased at 12.5 and 25 mg/kg compared to that in controls, there was a significant increase in the weights of the seminal vesicles/coagulating glands in all treated groups. The number of homogenization-resistant spermatids per testis and the daily sperm production per testis remained unchanged. The weight of the epididymis was significantly increased at 6.25 and 12.5 mg/kg. Moreover, the number of cauda epididymal sperm and the transit time were increased significantly at 6.25 mg/kg (10.2 days) compared to values in the control cauda (6.3 days). Neither serum testosterone levels nor LH was affected in a dosage-related manner. There were no effects of guanethidine treatment on cauda epididymal sperm motility or morphology. A quantitative analysis of detergent-extracted cauda epididymal sperm proteins by SDS-PAGE revealed no differences, but there were diminutions in seven proteins in homogenates of caput/ corpus tissue. Histologic analysis of testis and epididymis sections revealed no differences between control and denervated animals. In a subsequent experiment the lowest effective dosage (6.25 mg/kg) was given to rats for 1 wk, and an increased number of cauda epididymal sperm and a delay in sperm transit were observed. Our results indicate that low-dosage guanethidine exposure denervates the epididymis within 1 wk, thereby delaying epididymal transit; however, neither 1- nor 3-wk exposure produces qualitative changes in the sperm.

Sexual selection in a tropical fruit fly : role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field-cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME-fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME-fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field-cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant-derived chemicals.