Olof Söder

Nordic consensus on treatment of undescended testes

Aim: To reach consensus among specialists from the Nordic countries on the present state‐of‐the‐art in treatment of undescended testicles.

Expression of the neurotransmitter-synthesizing enzyme glutamic acid decarboxylase in male germ cells.

The gene encoding glutamic acid decarboxylase (GAD), the key enzyme in the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid, is shown to be expressed in the testis of several different species. Nucleotide sequence analysis of a cDNA clone isolated from the human testis confirmed the presence of GAD mRNA in the testis. The major GAD mRNA in the testis was 2.5 kilobases. Smaller amounts of a 3.7-kilobase mRNA with the same size as GAD mRNA in the brain was also detected in the testis. In situ hybridization using a GAD-specific probe revealed GAD mRNA expressing spermatocytes and spermatids located in the middle part of rat seminiferous tubules. Studies on the ontogeny of GAD mRNA expression showed low levels of GAD mRNA in testes of prepubertal rats, with increasing levels as sexual maturation is reached, compatible with GAD mRNA expression in germ cells. In agreement with this, fractionation of cells from the rat seminiferous epithelium followed by Northern (RNA) blot analysis showed the highest levels of GAD mRNA associated with spermatocytes and spermatids. Evidence for the presence of GAD protein in the rat testis was obtained from the demonstration of GAD-like immunoreactivity in seminiferous tubules, predominantly at a position where spermatids and spermatozoa are found. Furthermore, GAD-like immunoreactivity was seen in the midpiece of ejaculated human spermatozoa, the part that is responsible for generating energy for spermatozoan motility.

Neuropeptide Regulation of Human Thymocyte, Guinea Pig T Lymphocyte and Rat B Lymphocyte Mitogenesis

The effect of 15 defined neuropeptides on the mitogenic activation of lymphocytes from human thymus, guinea pig lymph nodes and rat spleen was investigated. Lymphocytes were incubated in the absence or presence of polyclonal T and B cell activators together with increasing doses of the neuropeptides, and harvested at 48 h of culture after pulse-labeling with 3H-thymidine to assess the DNA synthesis. A dose-related stimulatory effect on the spontaneous 3H-thymidine incorporation of human thymocytes was obtained with methionine-enkephalin (met-enk), motilin and neurotensin. Vasoactive intestinal polypeptide (VIP) and peptide HI (PHI) were inhibitory. A similar responsiveness was observed in cultures of phytohemagglutinin P (PHA)-activated human thymocytes. The low level of basal DNA synthesis of guinea pig lymph node cells was stimulated by VIP and inhibited by neuropeptide Y (NPY) and PHI. PHA-activated lymph node T lymphocytes were stimulated by neurotensin, bombesin and motilin, whereas NPY inhibited the thymidine uptake. The low rate of spontaneous DNA synthesis of rat spleen cells was increased in the presence of VIP. Met-enk stimulated both basal and dextran sulfate-activated splenic B cell proliferation, whereas PHI was inhibitory in both cases. The following peptides were found to be inactive in all the above assays: substance P, cholecystokinin-octapeptide, somatostatin, galanin, oxytocin, pentagastrin and gastrin-releasing peptide 1-27 and 14-27. Although the responses were generally of low magnitude and observed at high peptide concentrations, present study contributes to the understanding of possible mechanisms involved in interactions between the nervous and the immune system.

Role of transforming growth factor β in testicular immunosuppression

Abstract The potential role of transforming growth factor β (TGFβ) in the regulation of the immunological milieu of the testis was investigated. Antibodies neutralizing TGFβ reversed the previously observed suppression of rat peripheral blood lymphocyte proliferation induced by rat abdominal testis extract. Recombinant TGF β 1 dose-dependently inhibited testicular interleukin-1-like factor-driven proliferation of murine thymocytes and ConA-stimulated rat peripheral blood mononuclear cells. Extracts of seminiferous tubules contained a M r ∼25 K TGFβ-like growth inhibitor of the CLL-64 mink lung epithelial cell line. The present findings suggest an important role for TGFβ in testicular immunosuppression.

Isolation and partial characterization of an interleukin-1-like factor from rat testis interstitial fluid

Testicular interstitial fluid (ISF) was collected by in vivo perfusion of rat testes and analyzed for the presence of interleukin-1 (IL-1) activity by utilizing a murine thymocyte proliferation assay. IS obtained from nine rats were all positive with dose-response curves of IL-1 activity similar to those produced by rat testicular aqueous extracts, rat macrophage IL-1 and human recombinant IL-1 alpha. Chromato-focusing of pooled ISF revealed a single peak of IL-1 activity with an estimated isoelectric point of 6.1-6.3. HPLC size exclusion chromatography demonstrated two active peaks with apparent molecular ratios Mr of 15,000-18,000 and 5000-7000, respectively. The molecular properties of the 15,000-18,000 Mr component are very similar to those of an IL-1-like factor previously isolated from seminiferous tubules. Our results indicate that the testicular IL-1-like factor is secreted by the seminiferous tubules into the interstitial tissue. Its function in the testicular interstitium is unknown but it might be relevant for the tendency to testicular relapse of childhood lymphocytic leukemia.

Testicular immunoregulatory factors

The present data indicate that immune cells are regulated locally in the testis by Leydig cells, Sertoli cells and resident testicular macrophages. The effects of these cells are mediated by several peptide factors, including protectin, a group of high molecular weight testicular immunosuppressive factors, and testicular interleukin-1 alpha-like factor. The testicular interleukin-1 alpha-like factor is produced by Sertoli cells and is under hypophyseal control. Its synthesis starts at puberty concomitantly with the onset of spermatogenesis and it may act as a spermatogonial growth factor. Protectin, which is under hypophyseal control, may be involved in the mechanism of prolonged transplant survival in the testicular interstitial tissue. Its levels increase at puberty. Both the testicular interleukin-1 alpha-like activity and protectin may be important in testicular pathophysiology.

Occurrence, release, and effects of multiple tachykinins in cat colonic tissues and nerves

Neurokinin A (NKA)-immunoreactivities and substance P (SP)-immunoreactivities were found in picomolar amounts in colonic tissues and almost an order of magnitude higher amounts in vagal, pelvic, splanchnic, and lumbar colonic nerves of the cat. Continuous electric stimulation of the pelvic nerve at 4 Hz or intermittent electric burst stimulation of the pelvic nerve at 40 Hz during 1 second with 10-second rest periods produced a marked release of NKA-like immunoreactivity (NKA-LI) and SP-LI from the colon to blood (P less than 0.001). Reflex activation of the pelvic nerve by mechanical stimulation of the anus or rectal distension produced a less pronounced release of NKA-LI and SP-LI from the colon to blood (P less than 0.01). There was a simultaneous colonic contraction and vasodilation during each nerve stimulation. Reverse-phase high performance liquid chromatography showed presence of NKA, NKA oxide, NKA (3-10)/NKA (4-10), and neuropeptide K (NPK) in colonic tissues and release of all these molecular forms except NPK on nerve stimulation. Substance P and SP oxide were present both in colonic tissue extracts and in released material. Close intraarterial infusions of NKA, neurokinin B, SP, NPK, eledoisin, and physalaemin at doses of 0.1-100 pmol/min induced dose-dependent contractions of the proximal and distal colon (P less than 0.001) and vasodilatation (P less than 0.001), NKA being the most potent. The effects of the tachykinins were reduced after tetrodotoxin (P less than 0.05) and atropine (P less than 0.05) but unchanged after treatment with hexamethonium. Our findings indicate that tachykinins are released from the pelvic nerve to induce a nonadrenergic noncholinergic contraction and vasodilatation of the colon in the cat.

Interleukin-1β, but not interleukin-1α, induces acute inflammation-like changes in the testicular microcirculation of adult rats

A number of inflammatory mediators and cytokines were injected locally into the testis of adult rats in order to test their ability to induce leukocyte accumulation and increased vascular permeability (as studied by a carbon labelling technique). Human recombinant interleukin-1 beta (IL-1 beta) caused increased vascular permeability and leukocyte migration. All the other factors studied--histamine, serotonin, bradykinin, interleukin-1 alpha (IL-1 alpha), and a partially purified interleukin-1 alpha-like factor (tIL-1) from rat testis--did not induce any acute signs of increased vascular permeability or inflammatory response after local injection. It is suggested that local production of IL-1 beta from testicular macrophages could be responsible for the inflammation-like changes that are seen in rat testes after treatment with human chorionic gonadotrophin.

The Tachykinins Neurokinin A and Physalaemin Stimulate Murine Thymocyte Proliferation

The tachykinins constitute a family of neuropeptides that are released from sensory neurons, mediating a variety of responses termed neurogenic inflammation. The present study investigates the possibility that tachykinins are also involved in immune-regulatory mechanisms. The mammalian tachykinins neurokinin A (NKA), neurokinin B, neuropeptide K and substance P, as well as the nonmammalian tachykinin physalaemin (PHY) and eledoisin, were analysed in 10-pM to 1.0 microM concentrations for regulatory influences in several lymphocyte proliferation assays. NKA, and to a lesser extent PHY, but none of the other tachykinins tested, displayed a stimulatory action in murine thymocyte cultures, utilised as an interleukin-1 (IL-1) bioassay. The effect was apparent only at a concentration of 0.1 microM or higher. No further stimulatory effect of the tachykinins could be observed in thymocyte cultures already suboptimally stimulated to proliferation by addition of IL-1. The tachykinins had no effect in direct and co-mitogenic T and B lymphocyte proliferation assays with rat spleen cells, in a thymocyte growth peptide assay with mouse thymic lymphoblasts or in an interleukin-2 (IL-2) bioassay with IL-2-dependent rat splenoblasts. Our findings indicate that NKA and PHY can act as immune regulators. The results are relevant for the understanding of the interaction between the nervous and the immune system, and are of particular interest in view of the inflammatory actions of both tachykinins and IL-1.

Regulation of the testis

The testicular cells are regulated by factors produced locally in the testis. These factors include peptide growth factors, pro-opiomelanocortin derivatives, neuropeptides and steroids. Several agents able to affect steroido- and spermatogenesis can also affect leukocytes and many of the testis-regulating factors are produced by immune cells, suggesting that testicular cells and leukocytes may interact. In the present article, the effects of various testicular cell and leukocyte produced factors on steroido- and spermatogenesis are reviewed. The possibility that leukocytes may produce substances able to affect the testicular functions suggests that inhibition of immune system activation in the testis may be important also for reasons other than protection of autoantigenic germ cells from an autoimmune attack.